Full text of "Steam turbines; a treatise covering U.S. naval practice"

See other formats

Google

This is a digital copy of a book that was preserved for generations on library shelves before it was carefully scanned by Google as part of a project

to make the world's books discoverable online.

It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject

to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books

are our gateways to the past, representing a wealth of history, culture and knowledge that's often difficult to discover.

Marks, notations and other maiginalia present in the original volume will appear in this file - a reminder of this book's long journey from the

publisher to a library and finally to you.

Usage guidelines

Google is proud to partner with libraries to digitize public domain materials and make them widely accessible. Public domain books belong to the
public and we are merely their custodians. Nevertheless, this work is expensive, so in order to keep providing tliis resource, we liave taken steps to
prevent abuse by commercial parties, including placing technical restrictions on automated querying.
We also ask that you:

+ Make non-commercial use of the files We designed Google Book Search for use by individuals, and we request that you use these files for
personal, non-commercial purposes.

+ Refrain fivm automated querying Do not send automated queries of any sort to Google's system: If you are conducting research on machine
translation, optical character recognition or other areas where access to a large amount of text is helpful, please contact us. We encourage the
use of public domain materials for these purposes and may be able to help.

+ Maintain attributionTht GoogXt "watermark" you see on each file is essential for in forming people about this project and helping them find
additional materials through Google Book Search. Please do not remove it.

+ Keep it legal Whatever your use, remember that you are responsible for ensuring that what you are doing is legal. Do not assume that just
because we believe a book is in the public domain for users in the United States, that the work is also in the public domain for users in other
countries. Whether a book is still in copyright varies from country to country, and we can't offer guidance on whether any specific use of
any specific book is allowed. Please do not assume that a book's appearance in Google Book Search means it can be used in any manner
anywhere in the world. Copyright infringement liabili^ can be quite severe.

About Google Book Search

Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers
discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web

at |http: //books .google .com/I

FIGURE 168.

Oil Nozzle for Clearing.

/Art

,/r^^

STEAM TURBINES

A TREATISE COVERING U. S. NAVAL PRACTICE

.BY

G^ J: MEYERS

Lieutenant Commander, U. 5. Navy

ANNAPOUS, MD.
THE UNITED STATES NAVAL INSTITUTE

1917

COPTBIOHT, 1917, BT

J. W. CONROY
Trustee for U. 8. Naval Institute

BAinifOBI, KB., V. ■• A.

192 STEAM TURBINES.

CONYNGHAM^S System (FIGURE 160). The CONYNGHAM'S forced
lubrication system is a type installation for destroyers. There is one 500-gallon
storage tank, one 50-gallon storage tank, one 200-gallon drain tank, two 200-
gallon settling tanks, an oil cooler, and two oil pumps. The circulation of oil
for the entire turbine installation is accomplished by the two pumps. The
pumps are installed. so that both pumps can perform the same fimctions.

Ea(4i storage tank has a pipe running to the deck for filling. Oil flows
from the large storage tank by gravity to the suction common to both pmnps.
This method is used to supply additional or new oil to the system at any time.
Both pmnps have a common suction from the drain tank, a connnon discharge
to the settling tanks, and a common discharge through the cooler to the bear-
ings and gearing.

With one pump in operation, oil is taken by the pmnp from the drain
tank and discharged through the cooler to the bearings and gearing. The oil,
after running from the bearings and gearing, drains to the drain chambers
beneath them and then through drain pipes to the drain tank.

Whenever the oil becomes thick it may be removed from the svstem bv
the second piunp and discharged to one of the settling tanks. When not under
way, the drain tank may be emptied by either piunp and the oil discharged
to one of the settling tanks. Great care must be exercised to prevent the
drain-tank suction of the pump operating on the bearings from becoming
uncovered. When oil is removed from the system to one settling tank, new"
oil may be supplied from the storage tank, or the oil in the second settling tank
may be rim by gravity to the drain tank. Or, when under way, oil may be
pumped by both piunps from the drain tank, the after pump discharging
through the cooler to the bearings and gearing and the forward pump dis-
charging to one of the settling tanks. In this case the bottom drain from the
settling tank is closed and the overflow pipe from the settling tank to the
drain tank opened. Thick oil will go to the bottom of the settling tank and
the thinner oil will flow to the drain tank from the top of the settling tank
through the settling tank overflow^ pipe.

There is a drain from each of the settling tanks and from the drain tank
to the bilge for draining ofi" water from these tanks. The height of water is
indicated by gage glasses attached to the tanks. A drain leads from the bottom
of the 50-gallon storage tank to a drip-pan for supplying oil for oil-cans for
hand oiling of such machinery as is not fitted with forced lubrication.

The supply pipes to bearings and gearing and the pmnp suctions are
fitted with strainers to prevent any solid matter being carried by the oil to the
bearings.

The drain tank is installed sufficientlv below the turbines to allow oil to
run freely from all bearings and gear box to the drain tank.

CONTENTS.

Chapter I.

INTRODUCTORY.

PAGE

steam Turbine. — Mechanical Parts. — Action of Steam. — Classification. — ^Radial Flow. — Axial Flow. —
Impulse Turbine. — Impulse. — Simple Impulse Turbine. — Reaction Turbine. — ^Reaction. — Simple
Reaction Turbine 1

Chapter II.

THERMODYNAMICS.

Definition. — Energy. — Potential Energy. — Kinetic Energy. — Graphic Representation. — British Thermal

Unit. — ^Absolute Temperatures. — ^Joule's Equivalent. — ^Work and Heat — Power. — Horse-power. 5

Chapter III.

THE PROPERTIES OF STEAM.

Definition. — Formation of Steam. — General Definitions: Heat of the Liquid above 32 <* F., Latent Heat
of BiVaporation, Total Heat of the Steam, Saturated or Dry Steam, Wet Steam, Ehitropy of
Steam and Water, Ehitropy of Water, Entropy of Evaporation, Entropy of Steam. — Steam
Tables. — Specific Volume of Steam. — Specific Heat of Steam or Water. — Graphic Representa-
tion. — ^Water-Line. — Quality. — Steam-Line. — Adiabatic Expansion. — Specific Volume. — Rankine
Cycle.— Efficiency.— Calculation of the Values of Areas.— Quality During Adiabatic Expansion.—
Superheat 9

Chapter IV.

STEAM NOZZLES.

Introduction. — Purpose. — Steam Passages. — Critical Fall. — Converging Nozzles. — Converging-Diverg-
ing Nozzles. — Friction. — Efficiency. — Steam Expansion. — Graphic Representation of Steam
Action in an Expanding Nozzle. — ^Areas at Throat and at Exit 15

Chapter V.

PRINCIPLES OF DESIGN.

Historical. — Practical Considerations of Design. — Principles of Design. — Simple Impulse. — ^Velocity
Diagram. — Indicated Work. — Pressure Staging Impulse. — ^Velocity Compounding Impulse. —
Pressure Velocity Compounding Impulse. — Maximum Efficiency for Simple Impulse. — ^Velocity
Diagram for Simple Impulse. — ^Velocity Diagram for Velocity Compounded Pressure Stage. —
Indicated Work. — ^Action of the Steam Illustrated by the TE Diagram. — Reaction Compound-
ing. — MATimiiTn Efficiency for Simple Reaction. — Velocity Diagram for Simple Reaction. —
Velocity Diagram of a Reaction Expansion. — Action of the Steam Illustrated by the TE Diagram.
— ^Principles Used in Marine Turbines 23

Chapter VI.

BLADES.

Purpose. — Buckets. — ^Requirements. — Material. — Impulse Blades. — Thickness at Middle. — Blade with
no Shock. — Inlet Angle too Small. — Thickness of Edges. — Blade with 30 » Shock.— Reaction
Blade. — Ratio of Entrance to Exit — Blade Annulus Area. — Blade Height. — Securing Blades.. 41

Chapter VII.

MARINE TURBINE CONDENSING PLANTS.

Necessity for High Vacuua. — ^Reasons for the Development of Modem Condenser Plants. — ^Limits
of Expansion of Steam. — ^Work Done Compared on the PV Diagram.— Work Done Compared on
the TB IMagram. — Failure of the Vacuum. — Percentage of Gain for Turbines by Increase of
Vacuum. — ^Mechanical Parts of a Condensing Plant — Surface Condenser. — ^Requirements of a
Ccmdensing Plant— Condensers for Turbine Installations. — ^Weir Unifiux Condenser. — Con-
traflow Condenser. — Bent Tube Condenser. — ^Air-Pumps. — Air-Pumps for Turbine Installations.
— ^The Parsons Augmenter. — Kinetic System. — ^Westinghouse Air Ejector. — Morison Air Ejector.
—Weir Dual Air-Pump.- Blake Twinplex Pump. — ^Twin Air-Pumps. — LeBlanc Rotary Pumps. . 49

VI CONTENTS.

Chapter VIII.

THE PARSONS TURBINE. „^„„

PAGE

General Description. — ^Ezpansioos. — Arizona's Turbines.-— Wadsworth's Turbines. — ^H. P. Turbines.
— Rotor. — Dummy Piston and Packing. — Casing. — Shaft Glands. — ^Adjusting and Thrust
Blocks. — Cruising Expansions. — L. P. Turbines. — Rotor. — Dummy Piston and Packing. —
Casing. — Shaft Glands and Adjusting Blocks.— <}eared Cruising Turbines. — Expansions. —
Shaft Gland Leak-offs. — Pressures in Expansions of Arizona's Turbines. — General Details. —
Blading. — Segment Former. — Main Bearings. — Steam Connections. — Drains. — Balancing Rotors.
— Static Balance. — Dynamic Balance 65

Chapter IX.

THE CURTIS TURBINE.

General Description. — Tucker's Turbines. — Nevada's Turbines. — Cruising Turbine. — Rotor. — Bearings
and Adjusting Block. — Casing. — Diaphragms. — Nozzles. — Increasing Volumes of Steam. — Shaft
Glands. — Turbine of Small Size: General Description, Rotor, Velocity Compounding, Simple
* Pressure Stages, Diaphragms, Casing, Astern Turbine, Shaft Glands. — Turbines of Large Size:
H. P. Turbine, L. P. Turbine, L. P. Astern Turbine, Cruising Turbine, Rotors, Diaphragms,
Casings, Shaft Glands. — General Details: Main Bearings, Adjusting and Thrust Blocks, Blading,
Foundation Ring, Steam Connections, Drain Connections. — New Mexico's Turbines 89

Chapter X.

MIXED OR COMBINED TURBINES.

Introduction. — Definition. — Parsons Turbine. — ^Westinghouse Turbine. — Impulse Blading. — Reaction

Blading. — Plan Arrangement of Turbines 113

Chapter XI.

HEAT LOSSES. SUPERHEAT.

Heat Losses: Turbine Speed, Propeller Speed, Compromise Between Propeller Speed and Turbine
Speed, Steam Friction Losses, Reaction Turbine Losses, Parsons Total Losses, Parsons Partial
Losses, Pressure Velocity Compounded Impulse Turbine Losses, Curtis Total Losses, Curtis Par-
tial Losses. — Superheat: Superheated Steam, Disadvantages of Superheat, Requirements of
Superheaters for Marine Purposes 119

Chapter XII.

TRANSMISSION.

Introduction. — Systems of Transmission. — ^Reciprocating Engines and Turbines. — ^Mechanical Reduc-
tion Gear. — ^Wadsworth's Arrangement. — Cruising Turbine Reduction Gear. — Clutch. — Electri-
cal Transmission. — New Mexico's Arrangement. — Hydraulic Transmission 123

Chapter XIII.

TURBINE INSTALLATIONS.

Introduction. — ^Utah. — Arizona and Idaho. — Nevada. — Pennsylvania and Mississippi. — Preston. — ^Wads-
worth. — Cummings. — Conjrngham. — Conner and Stockton. — Perkins and Mayrant — Duncan and
Parker. — Gushing. — General Description. — Low Cruising Speeds. — High Cruising Speeds. — Full
Speed. — Backing and Maneuvering 139

Chapter XIV.

TURBINES FOR AUXILIARY MACHINERY.

Turbines of Small Sizes. — ^Principle Used. — De Laval Turbines: Velocity Compounded Turbines, Pres-
sure Compounded Turbines. — ^De Laval Blading. — ^Kerr Turbines: Pressure Compounded Tur-
bines. — General Electric Turbines. — ^Westinghouse Turbines. — Sturtevant Turbines. — Terry
Turbines 161

Chapter XV.

LUBRICATION.

Theory. — ^Requirements. — ^Lubricant Used. — ^Turbine Lubrication. — Forced Lubrication. — Nevada's

System. — Conyngham's System 185

CONTENTS. VII

Chapter XVI.

INSTRUCTIONS FOR THE CARE AND OPERATION OP PARSONS TURBINES.

PAGE

Forced Labrication.^Warming Up. — ManeoYering. — ^Main Turbines or Full Power. — Oruising. —
Turbine Qland Arrangement— Closing Down Turbines.— General.— Adjusting Turbines.— Open-
ing out Turbines for Internal Inspection. — Gearing 193

Chapter XVII.

INSTRUCTIONS FOR THE CARE AND OPERATION OF CURTIS TURBINES.

Forced Lubrication. — ^Warming Up. — Maneuvering. — Continuous Running. — Full Speed. — ^Turbines

Idle. — General. — ^Adjustments 211

Appendix.

Decision of the United States Circuit Court of Appeals in the Case of the International Curtis Marine
Turbine Company and Curtis Marine Turbine Company of the United States vs. William Cramp
A Sons Ship and Engine Building Company 217

INDEX

243

CHAPTER I.
INTRODUCTORY.

Steam Turbine. The steam turbine is a motor designed to convert the
heat energy of steam into rotary motion.

The conversion is accomplished by transforming the available heat energy
of steam into kinetic energy by expansion from a high pressure to a lower
pressure, the steam during its expansion being so mechanically controlled as
to convert its kinetic energy into mechanical energy.

Mechanical Parts. The mechanical elements for the conversion of the
kinetic energj^ into mechanical energy are : ( 1 ) a rotor attached to the revolv-
ing shaft through which it is desired to transmit power; (2) suitably arranged
blading or vanes attached to this rotor upon which the kinetic energy acquired
by the steam upon expansion may act to produce rotary motion; and (3),
surrounding the rotor, a stationary casing with nozzles and stationarj^ blading
to control the direction of flow and the path of the steam.

Action of Steam. In a reciprocating engine working expansively, steam
is admitted at practically boiler pressure until the i^oint of cut-off is reached.
Up to the point of cut-off, the action of the steam on the piston is at the pressure
of admission, but during the rest of the stroke tlie piston is pushed ahead as a
result of the expansion of the steam in the cylinder, or as a result of the action
of the heat energy of the steam encased in the cylinder. The expansion of the
steam takes place because the opposite side of the piston is connected to the
exhaust ports of the cylinder, which are under less pressure than the admission
ports. The reciprocating motion imparted to the piston by the steam is con-
verted into rotary motion by means of the connecting rod and the crank
attached to the shaft. On the other hand, in the steam turbine, while the
process of expansion is the same, the flow of the steam is continuous instead
of intermittent. Steam is first forced into the reciprocating engine cylinder
by the pressure in the boiler and then is allowed to expand by virtue of its
owTi internal heat energ\\ In the turbine the steam is continuously pushed
into the nozzle by the pressure at the inlet. During passage through the nozzle,
it expands continuously because of its internal heat energy. Each particle of
steam as it expands pushes the particles ahead of it forward at a faster rate and
so increases the velocity of flow\ Expansion is possible because the nozzle exit
pressure is less than the nozzle entrance pressure. Although the steam turbine
and steam piston engines are different in outward form, they are equivalent
in that the conversion of heat energy into kinetic energy is effected by expan-
sion of the steam.

Classification. Turbines are classified according to the direction of flow
of steam and according to the action of the steam as it flows through the tur-
bine. The direction of flow defines radial-flow turbines and axial-flow turbines.
The action of the steam defines impulse and reaction turbines.

Radial Flow. In radial-flow turbines, the steam, while passing through
the blades, flows in the general direction of the radius of the turbine. The force

2 1

2 STEAM TURBINES.

of the steam on the blades may be resohed into oomi>oneiits only along the
pei-iphery of the rotor and along the radius of the rotor.

A simple form of a radial-flow turbine is shown in FIGURE 1. The steam
flows through nozzles n and then in the general direction of the radius, exerting
a force on the blades b. The force x of the steam may be resolved along the
periphery of the rotor at y and along the radius at z. The component producing
motion of the I'otor is the force y.

Since in marine turbine practice we have to deal only with the axial-flow
turbine, there will be no further discussion of the radial-flow turbine.

Axial Flow. In axial-flow turl)ines, the steam, while passing thi-ough the
blades, flows in the general direction of the axis of the rotor. The force of the
steam on the blades may be resolved into components only along the periphei-y
of the rotor and along the axis of i-otation.

zzles
tor

FIGURE 1. FIGURE 2.

Radial Flow. Axial Flow.

The action of a simple axial-flow turl)ine is shown in FIGURE 2. The
steam flows through nozzles n and then in the genei'al directioii of the rotor axis,
exerting a force x on the blades b. The force of the steam may be resolved
along the periphery of the rotor at y, and along the axis of the rotor at z. The
component pi-oducing motion of the rotor is the force y.

Impulse Turbine. In the impulse turbine, the expansion of tlie steam is
completed within the stationary nozzles. There is no exijansion of the steam
as it passes through the blade spaces. The exjjansion in the nozzles results in
giving velocity to the jet of steam. The steam is, therefore, discharged fmni
the nozzles against the blades of the rotor with a certain force which imparts
motion to the blades and to the rotor to whicli the blades are attached. The
blades cause a change of direction of the steam flow. The pressures in the
clearance spaces between the casing and the rotating blades are at all points
practically equal, but less than the steam pressure at the nozzle entrance.

Impulse. From this action of the steam is derived the deflnition of im-
pulse. Impulse is the dynamic pressure exerted upon some object, as a vane

INTRODUCTORY. 3

or blade, by a jet possessing kinetic energy, the jet experiencing a change in
direction of flow.

Simple Impulse Turbine. The action of the steam in a simple impulse
turbine is shown in FIGURE 3. The expansion of the steam takes place in
nozzle n. It then discharges against the surfaces of the blades b and imparts
motion to them and to the rotor to which they are attached. The blades cause
the steam to change its direction of flow. The pressures at p and pi are equal.
The velocity at pi is less than the velocity at p. The force and direction of the
steam as it leaves the nozzle is x; the peripheral component producing rotary
motion is y; and the axial component is z. With this type of blade, the action
of the steam would be ineflScient because it would have a high residual velocity
in the direction of rotation when it leaves the blade spaces j therefore, blades
of the general form shown in FIGURE 4 are used, and this type ^viU be meant
hereafter when writing of impulse blades.

FIGURE 3. PIGXJRE: 4.

Impulse. Impulse.

The velocities in an impulse turbine are extremely high. The reaction
effect or pressure drop of the steam while passing through the moving blade
spaces of an impulse turbine is so slight that it can be neglected. The chief
characteristic of the impulse turbine is that the expansion of the steam occurs
wholly in the stationary nozzles.

Reactkm Turbine. In the reaction turbine, the expansion of the steam
takes place in the guide and moving blade spaces. The expansion in the blade
spaces results in increasing the velocity of the steam as it passes through and
from the blade spaces. The form of the blades causes a change in direction of
flow of the steam. The kinetic energy of the steam thus acquired reacts upon
the blades of the rotor due to the increase of velocity of the steam. When the
steam passes over the blade surfaces it imparts motion to the blades in the
direddoQ opposite to the new direction of steam flow. The pressure in the
dearance between the easing and rotating blades is greater at the entrance than
at the exit to the blade spaces.

4 STEAM TURBINES.

Reaction. From this performance of the steam is derived the definition
of reaction. Reaction is the pressure opposite in direction to that of the flow
of a jet, resulting from and accompanying a change of velocity of the jet

Simple Reaction Turbine. The action of the steam in a simple reaction
tm-bine is shown in FIGURE 5. The steam flows through the nozzle or guide
blade spaces n with partial expansion and then imparts a small impulse to the
blades b. After entering the blade spaces the steam changes its direction of
flow, expands still further, and acquires additional velocity. The increase of
velocity creates a reaction force which causes the blades attached to the rotor

FIGURE 6.

Reaction.

to move in a direction opposite to the steam flow as the steam leaves the rotor
blade spaces. Provision is made, if necessary, for the increased expansion in
the movii^ blade spaces by making them divergent in the direction of flow, as
shown in cross-section at s. The pressure at p is greater than the pressure at
Pi. The reaction force of the steam as it leaves the blade spaces is x; the
peripheral component producing motion is y; and the axial component is z.
The velocities in a reaction turbine are extremely low and therefore the impulse
is small. The chief characteristic of the reaction turbine is that the expansion
of steam is continuous throughout the guide and moving blades from the time
the steam enters the first row of guide blades.

CHAPTER II.
THERMODYNAMICS.

Definition. It has been shown how heat energy of steam is transformed
into kinetic energy by expansion, and how this again is converted into mechan-
ical energy by the action of the steam upon the blades of the rotor. The study
of the relations that exist between the heat energy and the mechanical energy
is known as thermodynamics.

Energy. Energy is the ability to overcome resistance. The measure of
that form of energy known as mechanical energy or work is the product of the
force and the distance through which the force acts. The imit of energy in
British imits is the foot-pound. The foot-pound is the work done against
gravity in lifting one poimd through a space of one foot.

Potential Energy. The energy of steam under pressure when the steam
has no velocity is potential energy, or energy of rest; for example, the steam
in the boiler. The heat acquired by the steam in the process of its formation
imder pressure is converted into kinetic energy, or energy of motion, when it is
made to expand through nozzles from one pressure to a lower pressure.

Kinetic Energy. The form of energy peculiar to the steam as it expands
is then kinetic energy, or energy of motion.

The equation for kinetic energy, which is the formulation of Newton's
first and second laws of motion, is derived as follows :

Force = mass X acceleration = mass X change of velocity

time of change

then F = MX ^'~^\ (1)

where F is the force in pounds,

Vi is the initial velocity in feet per second,
V2 is the final velocity in feet per second,
t is the time in seconds,

M is the mass and = .

9
The work performed or energy exerted in accelerating a body is the product

of resistance met and the distance covered while the velocity is being decreased.

This distance h is the product of the time of action and the mean velocity, or

h = YL+Zlxt. (2)

The work done or the energy exerted, E, is the product of force and distance ;

and simplifying, rv* — V'^

substituting for M its value, — , where W is the weight in pounds and flr is the
acceleration due to gravity (32,16 per second),

E^Eii^Lm. (3)

6 STEAM TURBINES.

If the velocity is increasing from Vi to Vi the equation would be

^~ 2^ •

(*)

(5)

And if the initial velocity, Vi, is zero,

Graphic Repretentation. The graphical method of representing mechan-
ical work is by means of the pressure-volimae (PV) diagram. In laying out
such a diagram, FIGURE 6, two co-ordinates are used, OX representing pres-
X

PV Diagram.

sure and OY repr^enting volumes. They are drawn through the point O
which is the zero of volume and pressure. Areas such as abed on this diagram
represent foot-pounds of mechanical work.

"ad
Cntropy

FIGURE 8.

TE Diagram.

Similarly, heat energy may be represented by the area of a diagram,
FIGURE 8, constructed with vertical ordinates of absolute temperatures and
horizontal dimensions obtained by dividing the number of heat imits added
or subtracted during any change in temperature by the mean absolute tempera-
ture during that change. The horizontal distance of any point from the vertical
axis OX of the heat diagram is called its entropy. This term, entropy, gives
to the heat diagram the name temperature-entropy (TE) diagram.

THERMODYNAMICS.

The analogy between the work diagram and the heat diagram may be
further explained by selecting some one part of the diagram, FIGURE 6, as
the expansion line be, which is reproduced in FIGURE 7. The area abed
imder this curve represents the work done during the change brought about
by the expansion from b to e* The mean pressure during the change is h. The
voliune at the start is represented by the distance Oa; the volume at the end
by Od; and the change of volmne due to the expansion by ad. Now the area
ahcd = product = width X mean height, or = ad X h. Hence for the pressure-
voliune diagram.

Work done in foot-pounds
during any change

change of
voliune in
cubic feet.

mean pressure during
► = -j change (poimds per [ x
square foot)

FIGURE 8 is the corresponding temperature-entropy diagram in which be
is the expansion curve showing a change in both absolute temperature and in
entropy. The area abed under this curve represents the heat units given up
by the working fluid during the expansion from temperature b to temperature
e. The mean absolute temperature during the change is h. The entropy at
the start is shown by the distance Oa; the entropy at the end by Od; and the
ehange in entropy due to the expansion from b to e by ad. Entropy is meas-
ured from the ordinate OX, therefore ad is not the entropy of point d, but is
the change in entropy during the change in the condition of the fluid from
b to e«

Entropy. As before, area abed = product = width X mean height, or
= adXh. Hence, for the TE diagram,

Nmnber of heat imits added or'
subtracted during any change
per poimd of the substance

'mean absolute
temperature
during change

change of
entropy.

From this is derived the definition for entropy. Entropy is a mathematical
expression determined by the equation :

p, * - , the heat in British thermal units added

^^ the mean absolute temperature during addition

British Thermal Unit. A British thermal unit (B. T. U.) is equal to one
one-hundred-and-eightieth of the heat required to raise the temperature of one
pound of water from the freezing point to the boiling point, at atmospheric
pressure of 14.7 poimds absolute.

Absolute Temperatures. Absolute temperatures are temperatures reck-
oned above absolute zero which is — 460"^ on the Fahrenheit scale.

Joule's Equivalent The mechanical equivalent of a British thermal unit
is 777.5 foot-pounds.

Woric and Heat The conversion of B. T. U.'s into foot-poimds would
be represented by the equation

777.5 XHn=E, (6)

where H is the heat change in B. T. U.'s,

n is the efficiency of expansion,
E is the work done expressed in foot-pounds.
Equating the values of E from (5) and (6),

E = 777.oX nn =

8 STEAM TURBINES.

Or, for example, where steam has acquired velocity V, due to expansion, and
has undergone a heat drop H expressed in B. T. U.'s, with efficiency n,

'"'*~2XpX 777.5'
or

2 X 32.16 X 777.5 50040 '
and the velocity Y acquired during the expansion is then expressed in terms
of the heat drop by the equation

F = ^^X 223.7. (7)

If W is imit weight (one poimd) then

Y = Vl^n X 223.7. (8)

The velocity thus acquired is transf omied into mechanical energy in a turbine
where a jet of expanding steam is directed upon suitably shaped rotating
blades.

When passing through the moving blade spaces where the initial and final
pressures are equal, the velocity of the steam relative to the moving blades is
reduced by the action of friction between steam particles and between the
steam and the blade surfaces. This reduction in velocitv is converted into heat.
This heat in B. T. U.'s expressed in terms of the velocity derived from equa-
tions (3) and (6),

E = 777.5 X g = ^(TV — F.^)
would be

2 X 32.16 X 777.5 ~ 50040 ' ^^

where

Fi is velocity of the steam relative to the moving blades on entrance to

the blade spaces,
Fa is velocity of the steam relative to the moving blades on exit from

the blade spaces,
W is the weight of steam in pounds,

B. is the B. T. TJ.'s of heat gained, due to change in velocity from Fi to

Fa, through resistance of friction.

When steam with an initial velocity Fi is expanding from a higher to a

lower pressure, and at the end of the expansion attains a velocity Fa, the heat

drop in B. T. U.'s expressed in terms of the velocity derived from equations

(4) and (6),

would be

^~ 50040 Xn • ^^^^

Power. Power is the rate of doing work, or is the work done in a given

interval of time. Its expression mathematically will be work done divided by

the time.

Hone-power. The unit of power in the British system is the horse-
power. A horse-power (H. P.) is the performance of 33,000 foot-pounds per
minute.

CHAPTER III.
THE PROPERTIES OF STEAM.

Definition. Steam possesses certain properties which have been found
by experiment to be constant for similar conditions of temperature and pres-
sure. A knowledge of these properties is necessary in the study of steam flow
and steam nozzle design for steam turbines.

Formation of Steam. Steam is first formed from water in the boiler by
the application of heat. The steps into which the steam forming process may
be divided are as f oUows :

First: Adding heat to the water to raise the temperature from 32 °F. to
the temperature of evaporation. The heat added is called the heat of the liquid
above 32°P., and the amount of heat added is measured in B. T. U.'s.

Second: Changing the water into steam at the temperature of evapora-
tion. During this process the temperatiu-e of the water does not change. The
process consists of breaking up and separating the particles of water, and of
increasing the volume from that occupied by water to that occupied by steam.
The heat required for the second step is called latent heat of evaporation and
is measured in B. T. U.'s. The amount of heat required for the first and second
steps is called the total heat of the steam, and comprises the total potential
energy of the steam.

Third: If superheated steam were produced there would be a third step
which consists of raising the temperatiu'e from that of saturated to that of
superheated steam. The heat added causes a rise in temperature with constant
pressure.

General Definitions. From the above process of forming steam from
water may be derived the following definitions:

Heat of the liquid above 32°F. is the niunber of B. T. U.^s necessary
to raise the temperature of a poimd of water from 32 °F. to a given
temperature.

Latent heat of evaporation for a given temperature is equal to the
number of B. T. TJ.^s necessary to convei-t one poimd of water at that
temperature into steam at the same temperature.

Total heat of steam for any given temperature is equal to the num-
ber of B. T. U.'s necessary to raise the temperature of a poimd of water
from 32°F. to the given temperature and evaporate it into steam at that
temperature.

Saturated or dry steam is steam formed in contact with water. It
has no suspended particles of water in it, and at any temperature it has a
corresponding definite absolute pressure.

Wet steam is steam that carries with it particles of water in sus-
pension.

Superiieated steam is saturated or dry steam that has had more heat
added to it when not in contact with water. Its temperature is higher
than that of saturated steam at the same pressure. The difference in
temperature is known as the ** degree of superheat. '^

10 STEAM TURBINES.

Quality of steam is the fraction by weight of dry or saturated steam

in a given weight of wet steam.

Entropy of steam or water is a mathematical term derived from the

relation :

^, ^ ^ the B. T. TJ.'s added to water or steam

Change of entropy= ir 1: — rir^z 1 3 — Tjnr-

® ^^ the mean absolute temperature during addition

The entropy of water is assumed to be zero at 32°F.

Entropy of Water. For any small change of temperature, the change
of entropy of water is equal to the B. T. U.'s added, divided by the absolute
temperature during addition.

Entropy of Evaporation. At any given temperature the change of
entropy for evaporation is equal to the latent heat of evaporation at the
given temperature, divided by the absolute temperature during evaporation.

Entropy of steam at any given temperature is equal to the sum of the
entropies of water and of evaporation at that temperature.

Steam Tables. Tables of the properties of saturated steam, used to facili-
tate steam calculations, contain columns of figures giving certain important
properties of steam. The following are the most important headings for steam
turbine calculations. The data given refer to one pound of steam or water as
the case may be :

1. Absolute pressure in pounds per square inch.

2. Temperatures of saturated steam corresponding to the pressure

given.

3. Heat of the liquid from 32^F.

4. Latent heat of evaporation.

5. Total heat of steam from 32^F.

6. Entropy of water.

7. Entropy of evaporation.

8. Entropy of saturated steam.

9. Density of saturated steam.

10. Specific volume of saturated steam.

11. Specific heat of steam and water.

Specific volume of steam at any given temperature and pressure is the
number of cubic feet of space occupied by one poxmd of wet, saturated, or
superheated steam.

Specific heat of steam or water is the difference between the number of
B. T. U.'s in water or steam at two temperatures with a difference of 1°F.

Graphic Representation. The various properties of steam may be shown
graphically on the TE diagram. This diagram for steam is printed for sale
and may be used for all the calculations that enter into turbine design. It is
made to represent all the data contained in the steam tables.

FIGURE 9 represents a TE diagram for water and steam. On it are shown
the various heat changes that take place due to the formation of steam from
water, to the expansion of steam, and to the condensation of steam. The data
on it represent values for one pound of water or steam.

The ordinates are absolute temperatures laid off in the direction of OX,
The abscissae are entropies laid off in the direction of OY. Lines be, nl and ae
are constant temperature and pressure lines and are called ** isothermals/ '

THE PROPERTIES OP STEAM. 11

Lines aai, bbi, nni, cci, etc., are lines of constant entropy and are called ** isoen-
tropic '^ lines. All areas represent heat expressed in B. T. U.'s. As in the
steam tables, it is assumed that water at 32^F. has zero entropy and contains
no B. T. U/s. The curve manb is the graphic representation of the properties
of one j)oiind of water as controlled by the amount of heat it contains and by
the pressure it is imder. It is known as the ^' water-line.^' It crosses the
vertical co-ordinate at 32°F. which is the point of zero entropy.

Water-Line. To find the successive points of the water-line above 32°F.,
it is necessary to find the change of entropy due to small changes of tempera-
ture; that is, due to small additions of heat to the water with corresponding
increases in the temperature. From the definition already given for entropy
of water,

™ . . . . B. T. U.'s added

Change of entropy of water = — , , . 1 — : tt^. — >

^ ^ mean absolute temperature durmg addition

successive entropy points may be found on the water-line corresponding to the
temperature selected.

At 100°F. the heat of the liquid, or the heat added necessary to raise the
temperature of the water from 32°F. to lOO^F., is 67.97 B. T. U.'s. The mean
absolute teiriperature during addition is

(460 + 32) + (460 + 100) _ ^^^ , (32 + 100)

2 — 4bU-h 2 •

Then

Change of entropy of water = , ' -^. = 0.1295.

Laying off this value of entropy at 100°F., 0.1295, from OX along the line of
constant temperature 100°F., gives the point a on the water-line. From a
draw the constant entropy line aai. The area maaiO is the heat of the liquid
at 100°F. = 67.97 B. T. U. 's.

At 200°F. the heat of the liquid above 32°F. is 167.94 B. T. U.'s. The heat
change between 100°F. and 200°F., or the heat added to raise the temperature
from lOCF. to 200''F., is the difference between the heat of the liquid between
these two temperatures ; that is, 167.94 — 67.97 = 99.97 B. T. U. 's. Then the
change of entropy between 100°F. and 200°F. is

99.97 ^ 59^ ^ 0.1643.

4gQ _^ (100 + 200) 510

As this value, 0.1643, represents change of entropy from 100°F. to 200°F., it is
necessary, in order to reduce all points on the water-line to the common origin
OX, to add the change of entropy between 32''F. and 100°F., which gives for
the entropy of water at 200''F.

0.1295 + 0.1643 = 0.2937.

Jjaying off this value of entropy of water at 200''F., 0.2937, from OX along the
line of constant temperature 200° F., gives the point n on the water-line. From
n draw the constant entropy line nni. Then mnniO is the heat of the liquid
at 200^P. = 167.94 B. T. U.^s.

In the same way successive points on the water-line may be f oxmd and laid
off, completing the water-line manb.

12 STEAM TURBINES.

If one pound of water at 32 °F. is heated until it reaches the temperature
350°F., its entropy increases and the change in temperature and entropy is
represented by line manb. The heat added during the change is represented
by area mbbiO. If the water at 350°P. is evaporated, the temperature will
remain constant and the line be will represent the change in entropy. The
heat required for this change is shown by the area bccibi, and is the latent
heat of evaporation. Area mbcciO is the total heat of the steam at point c
In the same way, water heated to any other temperature and then evaporated
will follow a similar process; that is, at any other temperature, such as ]00°F.,
heat added from 32T. will increase the entropy and temperature of the water
until 100°F. is reached at the point a. The heat added during the change
is represented by the area maaiO. If the water at 100 ""F. is evaporated, the
temperature will remain constant and the line ae will represent the change of
entropy. At point c the vaporization is complete and its distance from OX is
the entropy of steam at 100°F. The heat required for vaporization is shown
by the area aeeiai, and is the latent heat of evaporation at 100°F. Area
maeeiO is the total heat of the steam at point c.

Quality. During evaporation along be and ac, the steam is wet, or con-
tains particles of water in suspension in varying quantities, which are greatest
close to ab and zero along cc. At any point, as q on be, the percentage of dry
steam by weight contained in one pound of wet steam will be the same as at
some point qi on ae. Other points in the constant temperature lines may be
plotted to give the same percentage of dry steam in the wet steam as occur at
q and qi. If a cun^e is drawn through these points, we get the curve of constant
quality qqi. In the same way, curves of constant quality for other percentages
may be plotted, as rri and ssi.

Steam-Line. The curve ele represents the curve of 100 per cent quality,
or is the saturated or dry steam-line. It is also the line representing the con-
dition of expansion of steam from point e to point e if just enough heat were
added during the expansion to keep the steam always dry.

The entropy of the steam at point e is equal to the entropy of water at
point a plus the entropy of evaporation from a to e. The change of entropy
from a to e is equal to

latent heat of evaporation in steam at 100° F.
absolute temperature of evaporation '

or change of entropy from a to e = „ ' „ = 1.8505. The entropy of steam

at point e =1.8505 + 0.1295 = 1.98, which is the distance expressed in entropy
imits of e from the co-ordinate OX.

The entropy of the steam at point 1 is equal to the entropy of water at
point n plus the entropy of evaporation from n to L The change of entropy
from n to 1 is equal to

latent heat of evaporation in steam at 200"" F.
absolute temperature of evaporation '

977 8
or the change of entropy from n to \ = ' \y^r)f^ ~ 1-^824. The entropy of

steam at point 1 =1.4824 -f- 0.2937 =1.7761, which is the distance expressed in
entropy units of 1 from the co-ordinate OX.

THE PROPERTIES OF STEAM. 13

In the same way other points on the steam-line may be found and laid off,
completing the steam-line dc.

Adiabatic Expansion. When steam expands, doing work in a perfect
engine without external gain or loss of heat, it is said to expand adiabatically.
If there is no gain or loss of heat, entropy will remain constant from beginning
to the end of the expansion. Hence the representation of adiabatic expansion
of steam between 350''F. and 100°F. would be the isoentropic line cd.

Specific Volume. The voliunes of one pound of saturated steam at differ-
ent temperatures are sho\\Ti on the TE diagram along the saturated steam-line.
As these volumes have the same value as certain volumes of wet steam at
lower temperatures (assuming that the water in wet steam occupies no space),
lines may be drawn through points of equal value and are called curves of con-
stant volume. On FIGURE 9, curves V, Vi, V2, are curves of constant volume.

Rankine Cycle. When a perfect engine takes steam at a given tempera-
ture and pressure, expands it adiabatically, and exhausts it at a lower temper-
ature and pressure, it is said to operate on the Eankine cycle. This cycle is
used as a standard of comparison in steam turbine work.

The Bankine cycle on the TE diagram, FIGURE 9, is shown by area abed,
where expansion takes place from SSO'^F. to 100°F.

The temperature of the feed water as it enters the boiler is 100°F. The
heat in B. T. U.'s of one poimd of feed water is represented by area maaiO.
The water is heated from this temperature to 350°F., gaining entropy and tem-
perature as heat is added. This step is shown by line ab. The heat in B. T. TJ.'s
added to raise the temperature to that of evaporation is represented by area
abbiai. At b, evaporation begins and continues at constant temperature until
all the water is evaporated into dry or saturated steam at c This step is shown
by line be The heat in B. T. TJ.^s added during evaporation is represented by
area bccibi. From c, the steam expands adiabatically, neither losing nor gain-
ing heat, imtil it has expanded to the exhaust temperature of 100°F. at <L This
step is shown by line cd. From d, the steam is condensed to water without
change of temperature. This step is shown by line da, being the reverse of
evaporation. The heat lost to the condenser is represented by the area adciai.

EflBciency. The heat in B. T. U. *s, represented by area abed, is the value
of the potential energy of the steam between temperatures 350°F. and IWF.,
which has been converted by expansion into kinetic energy which in turn by
its action on the blading has been converted into mechanical energy, or the
work done. It is said to be the heat available for conversion into mechanical
energy. The area abcciai is the heat supplied to water at KWF. to make
steam at 350°F. The thermal efficiency of the Rankine cycle is the ratio
between the work done in B. T. U.'s and the heat supplied in B. T. U.^s, or

is the ratio . This ratio shows that the thermal efficiency of even a

aocciai

** perfect '' heat engine is very low.

Calculation of the Value of Areas. The value in B. T. U.'s of such areas
as abod may easily be foimd by measuring in terms of entropy the average
width, and in terms of temperature the average height of the areas. The
product of the height in temperature and of the width in entropy will give the
number of B. T. TJ. 's contained in an area.

14 STEAM TURBINES.

Quality During Adiabatk Expansion. During adiabatic expansion along
line cd, as heat is neither added nor subtracted from the steam, part of the
steam condenses and forms water in suspension. The steam, therefore, as it
expands, is wet steam, the percentage of dry or saturated steam decreasing as
the temperature falls. The quality of the steam at any point along this expan-
sion is therefore indicated, for example at 200°F., by the ratio — ^^ ; at lOO^P.

nd
by the ratio — .

Superheat. If at the point c heat were added to superheat the steam, the
change would be represented by the curve cf. The steam would remain at the
same pressure as at point c, but its temperature would be increased. The heat
in B. T. U.'s necessary to superheat to the point f would be that indicated by
the area cffiCi. Adiabatic expansion from point f would follow the line ffi
which will cross the saturated steam-line as shown.

FIGURE 9.

TE Diagram for Water
and Steam.

Entropy

CARE AND OPERATION OF PARSONS TURBINES. 209

Removing Propellers:

When removing or replacing a propeller on any line of shafting the
precaution should be taken to disconnect any one coupling and shore from
a bulkhead in one of the after compartments, as it is not intended that
any shock from hammering the propeller should be taken up on the tur-
bine adjusting block.

K. GEARING.

In connection with installations having mechanical reduction gearing the
following points require attention:

1. The pinion and gear-wheel journals should be checked regularly
with the bridge gages to note the amoimt of wear.

2. Attention should be paid to ensure that the tips of the oil sprayers
are free from dirt. In most cases means are provided whereby each
nozzle can be withdrawn and examined without stopping the machinery.

3. The temperature of the oil from drain well of gear box to be noted
at regular intervals.

4. Do not allow tips of gear-wheel to run in oil. This will tend to
heat up the oil supply excessively.

5. Attention to be paid to ensure that the gear-wheel and pinion
shafts are free to move in a fore and aft direction.

6. Where the gearing is used in conjunction with a cruising turbine,
the following points require attention:

(a) In most cases clutches are provided so that the cruising unit
can be disconnected when the main engines are in use.

(b) Before throwing in a clutch warm up cruising turbine
thoroughly.

(d) When connecting up, if clutch is of the jaw type, it is very
advisable to stop the main abaft to which the coupling is to engage
and connect up the turning gear of cruising unit, using this to bring
the teeth into line so that the claws will engage.

(e) Remarks regarding the operation of the cruising turbine
will be found to apply to the direct drive type.

Fii-st Stajie Nozzle of G. E. Cui-tis Turbine.

(Upper View, Exit Side: Lower View, Admission Side.)

CHAPTER IV.
STEAM NOZZLES.

IntroductioiL To arrive at an understanding of the principles of action
of the steam in the different types of turbines, it is necessary to study the
phenomenon connected with the flow of steam through orifices or nozzles.

PurpoM. In the steam tui'bine, the conversion of the heat energy of the
steam into kinetic energy or energy.of motion must be provided for. To accom-
plish this, the passages and nozzles of the turbine must be designed to control
the expansion of the steam in a way that will augment its velocity.

Steam Passages. In the De Laval and some other turbines, the steam
flows through nozzles which direct it against the blades of the rotating wheel.
In other turbines it flows through passages between guide vanes, which form
what is virtually a group of nozzles. In still other turbines both the stationary
guide vanes and the moving blades of the whole turbine have the same functions
as would have a collection of nozzles placed side by side. Whatever the
arrangement of the passages of a turbine, through which the steam passes,
they may be regarded as steam nozzles.

Oidcal FalL When steam is expanded in a parallel closed passage, there
are limits to the range of pressure through which expansion can be carried.
The point where this limit is reached is called the " critical fall." Referring
to FIGURE 10, the pressure in a boiler is p. Steam is expanded from this
pressure to the atmosphere through a hole bored in the boiler-plate. The
pressure pi, in the hole, will never be less than
0.58 of the pressure p. This relation between
p and pi is then expressed by the equation :

^ = 0.58, or_P-=1.72.

Assume that the pressure at p is 200 pounds , ^ »■

per square inch absolute, and that the pressure ' ,rj~

at pi can be regiilated to any desired amount. If av&oli '^ ' '

the pressure at pi be gradually decreased below ,^ ^

200 pounds per square inch, the first effect will
be for steam to flow from the high to the low
pressure, or from p to pi. As the pressure at
pi continues to decrease, more and more steam

will pass through the orifice at a gradually FIGURE 10.

increasing velocity. It will issue in a steady Steam Flowing Through
stream until the limiting pressure of 116 poimds ^-^ Orifice,

per square inch is reached (0.58 X 200 = 116).

After the pressure is lowered beyond this point, however much the pressure
at pi is reduced, the pressure in the orifice itself will never be less than 1 16
pounds i)er square inch. Owing to this, no greater weight of steam will flow
tlirough than did when the limiting pressure was reached. Further, as the

16 STEAM TURBINES.

pressure at pt is reduced below 116 pounds per square inch, the steam instead
of issuing in a steady jet will break up, making it impossible to utilize the
energy generated by the velocity attained during further expansion.

Convergins Nozzles. In the case of the orifice just considered, the comers
of the entrance end have not been rounded off, and hence there is considerable
loss of energy due to eddy currents. Experiment has
proved that these comers should be rounded off in all
nozzles, as shown in FIGURE 11, to improve their
efficiency.

It is immaterial whether the steam passage is of
circular or rectangular section. In practice, the cross-
sectional area of nozzles is generally rectangular.

When it is desired to expand steam to not less than

0.58 of its initial pressure, a nozzle with parallel sides

is used, as shown in FIGURE 11. The nozzle should be

kept as short as possible in order to reduce the energy

loss from skin friction. The parallel portion shown in

I dotted lines should, therefore, always be omitted if the

' steam can be turned into the correct direction without

FIGURE 11. it. In practice, however, the channel walls for a short

Converging Nozzle, space at the exit should be parallel, in order to keep the

steam from spreading to a width greater than the height

of the moving blades. This type of nozzle is called " convergent "; and, owing

to the fact that expansion is limited to the critical fall, it is also known as

the " non-expanding " nozzle.

EiiiSfi.

FIGURE 12.

Converging Nozzle.

The type of non-expanding nozzle used in practice is shown in FIGURE
12. The width of the nozzle is a. The walls from m to n are parallel to prevent
spreading of the steam at the exit. The dimension x is limited by the height
of the blades against which the steam discharges in order that the steam jet
will act on the total blade surface and at the same time will not discharge over
a greater area than is limited by the height of the blades. The dimension x
is the dimension of the nozzle in the direction of the turbine radius when the

STEAM NOZZLES.

nozzle is in place in the turbine. The angle d is the angle of inclination of the
nozzle to the plane of rotation of the blades against which the steam jet
discharges.

Omverging-Diverging Nozzles. When it is desired to expand steam to a
point below 0.58 of the initial pressure, the nozzle in which the expansion is
to take place must contain a contracted sec-
tion. The steam in passing through this con-
tracted section will expand to the limiting y//^ __ 71 e
pressure, that is, to 0.58 of the initial pressure.
The remainder of the required expansion must

be carried out in a gradually divergent pas- T.^ jA b

sage. This nozzle is shown in FIGURE 13. At v//Wf/////?))))Ui mwX^
a the pressure is equal to 0.58 of the initial
pressure, the remainder of the expansion
taking place in the divergent part from a to c

Experiments by Dr. Stodola have proved that FIGURE 13.

if the angle of the divergent part of the nozzle, Converging-Diverging Nozzle,
angle e, exceeds 5° the steam will leave the

walls of the nozzle. This type of nozzle is called ** convergent-divergent'';
and, owing to the fact that the expansion of steam can be carried beyond the
critical fall, it is also known as the ** expanding '' nozzle.

-X-

Side
Elevation

Plan

FIGURE 14.

Converging-Diverging Nozzle.

The type of expanding nozzle used in practice is shown in FIGURE 14.
The nozzle walls converge until the small dimension is reached at the throat a.
To carry out further expansion, the walls then diverge from a to b, the cross-
section at b being the area of the cross-section of the discharging jet of steam.
Prom m to n the walls are parallel to prevent spreading of the steam at exit.
The dimension z is limited by the height of the blades against which the steam
discharges in order that the steam jet will act on the whole blade surface and
at the same time wiU not discharge over a greater area than is limited by the
height of the blades. The dimension x is the dimension of the nozzle in the

18 STEAM TURBINES.

direction of the turbine radius when the nozzle is in place. The angle d is the
angle of inclination of the nozzle to the plane of rotation of the blades against
which the steam jet discharges.

Friction. In practice, there is frictional resistance to the steam flow not
only between the sides of the passages through which the steam flows, but also
between the particles of the steam itself. With the high velocities usual in
turbine work, a considerable amount of energy is utilized in overcoming the^se
resistances. This must be considered in the study of the flow of steam through
nozzles and passages.

Efficiency. Nozzle efficiency is the ratio between the B. T. U. 's converted
into useful work and the B. T. U.'s available for conversion into mechanical
energy when steam is expanded in nozzles.

Actual internal efficiency is the ratio between the B. T. U.^s converted into
useful work and the B. T. U.'s available for converaion into mechanical energy
during the expansion of the steam in a part of a turbine or in a whole turbine.

Efficiency referred to the Rankine cycle is the ratio between the B. T. U.'s
converted into useful work and the B. T. U.^s available for conversion into
mechanical energy on the Rankine cycle.

Steam Expansion. The kinetic energj^ expended in overcoming friction
and eddy currents is converted into heat energy. This heat energy has the
effect of constantly re-evaporating some of the water in the partially expanded
steam. The expansion does not, therefore, follow the adiabatic line, ch,
FIGURE IS, but will follow a curve somewhat to the right of the adiabatic
line, as at cfd.

This expansion line can be plotted if the efficiency of the nozzle is known,
and the range of pressure through which expansion is carried is given. Assmn-
ing an efficiency of 0.7 in expanding steam from 120 to 15 poimds per square ,,
inch absolute, or from a temperatm^e of 341 °F. to one of 213°F., two points *"<
on the expansion line will be calculated, that at 45 pounds per square inch * . ^^
absolute and that at 15 pounds per square inch absolute. . "^V

The heat drop on the Rankine cycle when steam expands from 120 to 45 ;'
pounds per square inch absolute is 77 B. T. U.'s, represented by area A, ^
FIGURE IS. Of this heat, 77 X 0.3, or 23.1 B. T. U.'s are used in overcoming
friction. This heat, 23.1 B. T. U.'s, is represented by area Ci^E (extending
from 341 °F. to absolute zero). As area C is very small it wilfbe neglected and
area E (extending from 274.5°F. to absolute zero) will be assmned to equal
23.1 B. T. U.'s. The increase of entropy due to friction of the expanding steam
from 120 to 45 pounds per square inch absolute will then be represented by e
and will be equal to

B . T. U.'s added ^^ . 23.1 _ ^ noi ^

absolute temp. 460 + 274.5

The heat drop on the Rankine cycle when steam expands from 45 pounds
to 15 pounds per square inch absolute is 78 B. T. U.'s, represented by area B.
Of this heat, 78 X 0.3, or 23.4 B. T. U.'s are used in overcoming friction. This
heat, 23.4 B. T. U.'s, is represented by area D + F (extending from 274.5°F.
to absolute zero). As area D is very small it will be neglected, and area

STEAM NOZZLES. 19

F (extending from 213°F. to absolute zero) will be assumed to equal 23.4
B. T. U.'s. The increase of entropy due to friction of the expanding steam
from 45 pounds to 15 pounds will then be represented by ei, and wiU be
equal to

B. T. IJ.'s added ^r to ^|^ = 0.0348.
absolute temp. ' 460 + 213

O Etttropy

FIGURE 16.

Expansion Line.

The values of e and ci can then be laid off and the expansion line drawn
thTou^ points c, f, and iL In a similar manner, the expansion line may be
constructed by finding the change of entropy due to each of a larger number
of smaller expansions.

The total heat used in overcoming friction, or the resisting work of fric-
tion during the total expansion, is called the " regenerated heat," and is
lepresented in FIGURE 16 by area b + c This heat, while it is used by the
steam in overcoming friction, adds an equal amoimt of heat to the steam. The
pert represented by areas above the condenser pressure or temperature are

STEAM TURBINES.

used in doing useful work as the steam expands. The total heat in the steam
at 120 pounds per square inch absolute is represented by area a + d + e. When
the steam expands adiabatically, the amount of heat given to the condenser is
represented by the area d. In the actual expansion, the total amount of heat
ds the same, but the heat given to the condenser is d + c The heat available
in the actual expansion is represented by the area a + b. The part of the
regenerated heat due to friction, represented by the area b, is useful heat
available for producing velocity towards the exit end of the nozzle, but is only

Expansion

Steam
Une

FIGURE 16.

Regenerated Heat.

a very small proportion of the total heat given up to the work of friction. The
useful heat is represented by area

(a + b) — (b + c) = (a — c).

The actual efficiency of the nozzle is the ratio, ^f/^l ^f^^ , which is equal

available heat

to 7 — rirv • The efficiency compared with the Bankine cycle is the ratio,

useful heat i.- i. . ^ j. (a — c)

Tj-r^ — r-— 7 ^ — p 7- , which is equal to ^ — ^ .

available heat on Rankine cycle ^ a

Graphic Representation of Steam Action in an Expanding Nozzle. The

representation of the action of steam in a converging-diverging nozzle is shown
in FIGURE 17. Steam at an initial absolute pressure of 200 pounds per square
inch is expanded to a final absolute pressure of 90 poimds per square inch.

STEAM NOZZLES.

The expansion to the limiting pressure will end at 116 pounds per square inch
at the throat of the nozzle. Assuming an efficiency of 0.9, the expansion line
may be plotted. The total heat available up to the throat will be 44.2 B. T. U.'s.
The useful work will be 44.2 X 0.9 = 40 B. T. U.'s. Assuming that the steam
has no initial velocity, the velocity it will have attained at the throat of the
nozzle will be from equation (8),

y= VHwX 223. 7,

V = V44.2 X 0.9 X 223.7 = 1414 feet per second.

too lb$.ab».

Heat available,
44.2 B.T-Us.

920

Heat available,

20.5 B.T.Vs. »

FIGURE 17.

Steam Action in an Expanding Nozzle.

The total heat available up to the exit will be 44.2 + 20.3 = 64.5 B. T. U.'s.
The useful heat will be 64.5 X 0.9 = 58 B. T. U.'s. The velocity it will have
attained at the exit of the nozzle will be

F=V64.5 X 0.9 X 223.7 = 1702 feet per second.

Areas at Throat and at Exit. The volume of a pound of steam at the
throat and the exit will be respectively 3.84 cubic feet and 4.91 cubic feet. The
areas required per pound of steam flowing per second will therefore be for the
throat,

3.84

for the exit,

1414

4.91
1702

X 144 = 0.391 square inch ;

X 144 = 0.415 square inch.

CHAPTER V.
PRINCIPLES OF DESIGN.

HistoricaL The effort to create a steam turbine of practical use dates
from the year 160 B, C, when Hiero of Alexandria built a crude form of reac-
tion wheeL In 1629, Branca, an Italian, showed how steam could be jetted
against a vane to produce rotary motion. While these tsvo instances strikingly
show the two broad principles of operation on which all modem turbine design
is based, no practical and efl&cient steam turbine working on either principle
was developed prior to 1884.

The development of the modem steam turbine has been gradual. The
main difficulty in aU efforts has been the excessive waste of steam as compared
with the reciprocating engine. By research and experiment, the steam con-
sumption per brake horse-power in turbines built in successive years has
gradually decreased imtil we have to-day large manufacturing plants devoted
to tiu-bine construction and the turbine coming more and more into universal
use. In marine practice, speeds have had to be reduced to meet economical
propeller speeds. The early designs of marine turbines gave excessive steam
consumption. This has led to the development of reduction gears with which
the later turbine ships are being equipped. The reciprocating engine has been
abandoned as propulsive machinery on torpedo-boat destroyers, and it is
probably safe to predict that the OKLAHOMA will be the last capital ship in
the U. S. Navy in which reciprocating engines will be installed.

Practical Considerations of Design. The practical steam turbine to be
efficient must be designed to accomplish the following:

1. Transform the available heat energy into kinetic energy.

2. Transform the available kinetic energy into mechanical energy.

3. Rotate at a speed that will be safe and economical.

4. Combine simplicity of construction with reliability of action.

Principles of Design. These considerations of design have caused to be
evolved the following principles upon which steam turbines for practical use
are now constructed, each principle being associated with the name of the
engineer who has been largely responsible for the development of turbines in
which it has been adopted:

1. Simple impulse — De Laval.

2. Pressure staging impulse — ^Rateau.

3. Velocity compounding impulse — Curtis.

4. Pressure velocity compoimding — Curtis.

5. Reaction compounding — Parsons.

The first four principles are used in impulse turbines; the last in reaction
turbines.

STEAM TURBINES.

Simple Inqiulie. The simplest possible arrangement of the impulse tur-
bine is shown in FIGURE 18, where n is a nozzle directing a jet of steam
against vanes or blades of a single wheel w inclosed in a casing c This is
similar to the Be Laval turbine, in which the whole expansion of the steam
from boiler pressure to exhaust pressure takes place in the nozzle. High
steam velocities are therefore acquired, and consequently high peripheral
velocities of the rotor result.

The pressure of the steam as it flows through
the nozzle and moving blades is shown in the diagram
below the turbine. The pressure decreases rapidly
through the nozzle, due to the expansion of the steam
as it passes through the nozzle. The presstire on
either side of the moving blades and in every part
of the compartment in which tiie wheel revolves is
practically equal to the exhaust pressure. The
velocity of the steam increases rapidly through the
nozzle and drops on passing through the moving
blades. There is, however, a residual velocity to the
steam as it leaves the moving blades.

The nozzle n is placed at an angle to the plane
of rotation of the wheel, and is of the convenient-
divergent type. It is so designed that the steam
imdergoing expansion in its passage through the
nozzle acquires a high velocity at the exit from the
nozzle. The losses from friction, radiation, and
eddying are reduced to a minimum. It will be noted
that the expansion of the steam is wholly in the
nozzle and that the steam flows through the moving
blades (which absorb its velocity) solely by virtue
of the inertia the steam possesses upon exit from the
nozzle. Friction losses will take place in the nozzle
^hs^ and as the steam passes through the moving blades.

y \ ^ The velocity diagram represents graphically the

Velocitieb ' **'^^"** ^^^ relative velocities of the steam, the

^ velocity of the rotor periphery, entrance and exit

blade angles, as the steam flows through the turbine.
From it may be calculated the indicated work done
^ ■ by the turbine.

Absolute velocity is the velocity of the steam with
regard to stationary parte. Relative velocity is the
velocity of the steam in regard to moving parts.
With a known nozzle exit velocity and a known angle of the nozzle to the
plane of rotation of the wheel, a theoretical velocity diagram may be con-.
structed, as shown in FIGURE 19. AB, or V, is the absolute velocity and
direction of the steam as it enters the moving blade spaces, or as it ^ues from
the nozzle. The angle the nozzle makes with the plane of rotation of the
wheel is a. CB, or u, is the velocity and direction of rotation of the wheel
periphery, drawn to the same scale as V. Having given AB and EC and the

Pressure s
FIGURE 18.

Simple Impulse.

PRINCIPLES OF DESIGN.

included angle a, the completion of the triangle will give the velocity diagram
for the entrance steam. The side AC, or Vi, is the velocity and direction of
the steam relative to the rotating wheel. The value V is called the absolute
entrance velocity ; the value Vi is called the relative entrance velocity.

For ease of understanding, consider V as the direction and value of the
velocity of the steam jet relative to the turbine casing; and Vi the direction
and value of the velocity of the entering steam relative to the moving wheel.

If the losses due to friction are not considered, the relative blade exit
velocity will be equal in value to the relative entrance velocity, or Va = Vi.
Assuming that the relative blade entrance and blade exit angles are equal,
b = biy and laying off V2 and u, the velocity diagram for the exit velocities is
constructed, giving CF, or Vs, for the value and direction of the absolute blade
exit velocity.

V = steam velocity from nosile exit.

V = Steam Telocity absolute at blade entrance.
yi= Steam velocity relative at blade entrance.
V,=: Steam velocity relative at blade exit.
Vt= Steam velocity absolute at blade exit.

p u = Peripheral velocity in feet per second of blades,
a = Angle of inclination of nossle to plane of rotation,
a = Absolute steam entrance angle at blade entrance,
b = Relative steam entrance angle at blade entrance,
bi = Relative steam exit angle at blade exit
bi= Absolute steam exit angle at blade exit

FIGURE 19.

Velocity Diagram — Simple Impulse.

This turbine must utilize steam flowing with a velocity of 3000 to 4000
feet per second, and has a wheel peripheral velocity of nearly one-half this
value to utilize the total energy of the steam. This makes a value for the
peripheral velocity of the De Laval turbine frequently as high as 1200 feet
per second, or as high as safety will permit with tiie strongest materials
obtainable for the rotating wheel and shaft.

The steam has a velocity Vi, FIGURE 19, on entering the bucket and
leaves it with velocity Va. In the change of velocity, the component AD (of
Vi) is preserved and reappears as DE. The component DC is destroyed and
an equal but opposite component CD is created. Thus the steam has received
an acceleration of DC + CD. By Newton's first and second laws of motion,
this acceleration can only have been produced by a force acting upon the steam.
This force is of course exerted by the blades and is in the direction CD. If
we consider a unit quantity of steam as one pound, then the magnitude of the
force with which the blade deflects the steam is

F = ma=-^X (DC + CD).

26 STEAM TURBINES.

By Newton's third law of motion, action and reaction are equal. The force
with which the steam presses on the blade in the direction DC is, therefore,

also -sK- X (DC + CD). This force is associated with motion of the blade

in its own direction; therefore, the work done by it is equal to

uX^(DC + CD).

This process is equally applicable if we consider absolute velocities. Relative
to the casing, the steam entered the blade spaces with velocity V and left with
velocity Vs. The acceleration is, then, the change of the component DB to the
comi)onent GF, or is DB + GF. This is equal to

DC + CD, since DB = DC + u, and GF = CD — u.

Pressure Staging Impulse. In turbines of large size, it is necessary to
avoid the high speeds of rotation which obtain in the simple impulse turbine.
This is accomplished by pressure staging and velocity compoimding.

The simplest form of the pressure staged turbine is shown in FIGURE 20
which illustrates the principle of the Rateau turbine. This in effect is a series
of simple impulse turbines like that of FIGURE 18, each of which is in a
separate compartment. There are usually enough compartments to have a
steam drop of not more than 0.42 of its initial pressure when flowing through
the nozzles from one compartment to the next. Converging-diverging nozzles
are therefore not required. In other words, the steam is expanded from boiler
pressure to condenser pressure in several stages. The expansion for each
stage takes place in the nozzles which discharge against the moving blades of
each stage. The velocity acquired during each expansion is utilized by a
separate wheel on which is one row of blades. The wheels are all secured to
the same shaft.

Steam enters through nozzles ni, FIGURE 20, and expands down to the
pressure in the first compartment. The pressure within the blade passages is
the same as that within the compartment in which the wheel revolves. To
insure a uniform pressure in all parts of each compartment, holes h are some-
times made through the wheel discs. The second set of nozzles ni has a cross-
sectional area larger than the first to accommodate the increased voliune of
the steam, and the same is true of the succeeding nozzles. This cross-sectional
area of nozzles is increased to take care of the increasing volmne of steam as
the steam passes through the turbine, either by increasing the arcs over which
the nozzles extend, by increasing the nozzle heights, or by increasing both the
arcs and the heights of the nozzles.

The velocity curve shows that there is a small amoimt of imused residual
velocity in each pressure stage. The pressure curve shows how the pressure
is gradually stepped down from boiler pressure to condenser pressure, a part
of the pressure being utilized to perform work in each stage.

The velocity diagram for each set of moving blades is similar to the
diagram for the simple impulse turbine.

224 APPENDIX.

imperative. Owing to contraction and expansion and other causes this was
attended with grave difficulty and sometimes resulted in stripping the revolv-
ing vanes. Clearance escapes, owing to the principle of operation of a reaction
turbine, could not be avoided. They could only be measureably minimized by
the most careful construction. Moreover, the intra-chamber, drop-pressure
feature of the Parsons chamber, subjected it to the mechanical objection of
axial or endwise thinist. This was due to the fact that there was a difference in
pressure — a pressure drop — ^between the inlet and outlet side of the vane. As
the relative proportion of clearance loss to vane-capacity increased as the vane
diminished in height, the reaction turbine was restricted to large sizes. All
this is clearly shown by complainants' witness, who says of the Parsons tur-
bine, that:

** Reljdng as it did upon reaction, (it") developed its power by the
pressure of the steam upon its vanes. Tnere was a drop in pressure
between the inlet and exit of each vane, consequently, clearance spaces
must be as fine as possible, in order to prevent excessive leakage. At the
time rotative speedis were very high compared with machinery other than
steam turbines. Consequently, it was extremely delicate and sensitive
to derangement by steiun erosion, intrusion of foreign substances, etc.
The fact tiiat it relied upon reaction also necessitated a vane speed vir-
tually equal to the steam speed. This need for high peripheral speed
prohibited the reduction of wheel diameters. Therefore, since the current
of steam must occupy the entire periphery simultaneously, the radial
dimension of the steam current in the earlier stages of the machine was
narrowly restricted. This minuteness also exaggerated the relative part
played by the clearance spaces and their leakages.**

While these objections of clearance, axial thrust, and prohibitive use of
smaU wheels due to the use of the reaction principle were avoided by use of
the impulse principle in De Laval's turbine, yet its use also disclosed serious
objections, due to its principle of operation. The tremendous speed it
developed forbade utilization of that speed in large wheels and necessitated
the non-economic practice of coimteracting or neutralizing it in the small
wheels where it could be used. It should here be noted, as throwing light on
the novel character of Curtis *s subsequent work, that this excessively high
speed of turbines was accepted as necessarily incident and the whole trend of
the engineering profession was to accept it as such. Thus in r^pondent's
proofs Bateau's address (heretofore referred to) says:

" The Girard screw-wheel, which succeeded so well as a hydraulic
motor, has given no public results as a steam apparatus. The failure of
the tests which I just related, should not of course be in the least surpris-
ing. The problem was, in fact, difficiilt to solve, because in order to secure
an economical operation, it is absolutely necessary to attain very high

speeds of rotation If steam turbines are compared with ordinary

motors both advantages and disadvantages are found. I would emphasize
as the principal disadvantages of turbines resulting from the great velocity
of rotation: (1) heating of the bearings; (2) the difficulty of driving
shafts rotating at lower speeds; (3) the difficulty in using a condenser.
I put aside for the moment the question of consumption of steam.'*

De Laval himself sought in different ways to control the high speed he
generated. In order to lessen the strain on parts he deVised a flexible central
shaft so small in diameter that when running at very high speed such shaft and

28 STEAM TURBINES.

Velf>city Compounding Impulse. In both the simple impulse and pres-
sure staged turbines, the steam leaves the blade spaces of each wheel with a
residual velocity and an attempt is made to utilize in only one row of moving
blades as much as possible of the velocity acquired by the steam in each set of

Vcloclti«»

4 S
II I

Pressures
FIGURE 21.

Velocity Compoimding Impulse.

nozzles. To utilize the residual steam velocity and to reduce the peripheral
speed of the wheel, velocity compounding is resorted to in the turbine shown
in FIGURE 21. That is, the velocity acqmred by the steam in eaoi set of
nozzles instead of being made to do work on only one row of moving blades
is made to do work on several rows of moving blades, part of this velocity
being absorbed by each row of blades.

PRINCIPLES OF DESIGN. 29

In FIGURE 21 the steam flows through the expansion nozzles n which
reduce its pressure to that of the turbine exhaust and of the compartment
in which the wheels Wi and W2 revolve. This expansion imparts velocity to
the steam. The steam then discharges against the blades b of the wheel Wi.
Its direction after passing through blade spaces of Wi is reversed. Its direc-
tion is again reversed by the guide blades g attached to the casing. It next
discharges from these guide passages against the blades c of the wheel W2
which is on the same shaft as wi. The steam, having acquired its velocity in
the nozzles n, flows through the blade spaces of the turbine by virtue of its
inertia, having just enough residual velocity to clear the moving blades c.
However, difficulty is experienced in making steam flow through groups of
irregular passages without any impelling force to overcome friction, other
than its own inertia. To supply the necessary impelling force to make up
for frictional losses, the height of the blade spaces from the point where the
steam strikes the first wheel to the point where it leaves the last wheel is
gradually increased. Thus the steam expands a small amount in the moving
and guide blade passages for the purpose of accelerating the steam velocity
sufficiently to compensate for its retardation by friction, although most of its
expansion takes place in the nozzles. The pressure is very slightly higher in
the blade spaces than in the compartment in which the wheels revolve, but
can be considered as practically equal at all points in this compartment.

The velocity curve shows the velocity of the steam increasing in the noz-
zles from 1 to 2. As it flows through the moving blades of wi, part of this
velocity is absorbed by the rotor. The height of 3 indicates the residual or
unused velocity of the steam as it leaves the flrst row of moving blades. Due
to increasing blade heights, as the steam passes through the guide blade spaces,
the velocity remains constant from 3 to 4. The remainder of the velocity is then
absorbed from 4 to 5 when the steam flows through the blade spaces of the
second wheel.

Velocity compoimding is carried out in practice to the extent of using as
many as four or even five rows of moving blades in a pressure stage to extract
all of the velocity acquired by the steam in its expansion in the nozzles.
Increasing the mnnber of blade rows for velocity compoimding increases the
area over which the steam must flow and results in an increase of the losses
from frictional resistance.

The pressure curve shows the pressures as the steam passes through the
nozzles and the wheel compartment. The pressure in the wheel compartment
is at all points practically equal to the turbine exhaust pressure, the steam
having been expanded from boiler pressure to exhaust pressure in the nozzles.

To save repetition, the velocity diagram, frictional losses, and work done
will be taken up under pressure velocity compounding, since the methods are
the same.

Pk-etsure Velocity Compounding Impube. By the use of pressure velocity
compounding, the Curtis turbine for marine purposes has been developed
to give low peripheral speeds, eliminate thrust, reduce steam leakage around
the tijMS of the blades, and provide for a rugged and mechanically simple
construction of turbine. The essential features of this principle are a
ntunber of pressure stages, in each of which velocity compoimding is carried
out ; that is, it is a combination of pressure staging and velocity compounding.

STEAM TURBINES.

To make this principle of practical use, converging and converging-diverging
nozzles are used where necessary. This is done in order that the several pres-
sure stages, while under conditions of fixed shaft speed rotation, will accom-
modate the steam flow at the successively diminishing pressures. The ratio
between steam velocity produced by the nozzles and blade or peripheral

^N?_1

[^Zb

C]b^

Velocities

II \ll II II 1

Pressures

FIGURE 22.

Pressure Velocity Compoimding Impulse.

speeds is practically the same for the several successive pressure stages of
the turbine.

FIGURE 22 shows the arrangement of nozzles and blading to illustrate the
principles of pressure velocity compounding. The pressure drop is divided
into two stages, marked 1st and 2d; that is, expansion of steam from boiler
pressure to exhaust pressure is carried out in two sets of nozzles. Each pres-

PRINCIPLES OF DESIGN. 31

sure stage is divided into two velocity stages. The steam is expanded from
boiler pressure to the pressure in the first wheel compartment, in the nozzles
Oj, acquiring velocity due to this expansion. The steam discharges from the
first set of nozzles against the first row of wheel blades bi in the first pressure
stage, passes through these blades with a change of direction into the guide
blades gi, where the direction of fiow is again changed. It then discharges
against the second row of wheel blades b* in the first pressure stage. The
steam then passes through a second set of nozzles n2 and is therein expanded
to the exhaust pressure of the tiu'bine, acquiring velocity due to this expansion.
The action of the steam in the second pressure stage is the same as in the first
pressure stage.

The velocity curve shows an increase in velocity as the steam passes
through the first set of nozzles from 1 to 2. As it flows through the first row
of moving blades bi of the first pressure stage, from 2 to 3, part of the velocity
is absorbed by this row of blades. The velocity through the first set of guide
blades gi, from 3 to 4, remains constant due to increasing blade heights to
compensate for its retardation due to friction. It issues from the row of guide
blades gi with the unused velocity at 4 and discharges against the second row
of moving blades gs of the first pressure stage, where, from 4 to 5, practically
the remainder of the velocity is absorbed. After discharging from the second
row of moving blades g2 in the first pressure stage, the steam is expanded to
the pressure of the turbine exhaust in nozzles n2, acquiring velocity due to this
expansion. The action of the steam as it fiows through the second pressure
stage is similar to that in the first pressure stage, the steam finally fiowing from
the last row of moving blades b4 to the turbine exhaust.

The purpose of the guide blades gi and g2 is in each pressure stage to turn
the steam, which has suffered a reversal of direction in the first row of moving
blades, back to approximately its direction upon exit from the nozzles in order
that the impulse due to the discharge from the guide blades will act in the same
direction as the impulse due to the discharge from the nozzles.

The pressure of the steam as it fiows through the turbine is shown on the
pressure curve. The pressure in the first wheel compartment is practically
equal at all points to the pressure existing at 2. The pressure in the second
wheel compartment is practically equal at all points to the turbine exhaust
pressure.

With the simple impulse turbine, in order that all the energy of the steam
be extracted, it is necessary that the steam emerge from the moving blades
with an absolute velocity, the component of which in the direction of rotation
is zero. Under this condition, the velocity diagram, FIGURE 23, is constructed
with V the absolute entering velocity, a the angle of inclination of the nozzle
to the plane of rotation, u the peripheral velocity of the rotor blades, Vi the
relative steam entrance velocity, V2 the relative steam exit velocity, and Vs the
absolute steam exit velocity.

If Vt is to have no component along DB, the plane of rotation, then lay off
CF perpendicular to this plane. As Fi = F2, neglecting friction, V2 and u may

be laid off. It is then evident that DB =2u, and that u = -^ cos a. The

oondition of maximum efficiency is, then, for a simple impulse turbine, that

STEAM TURBINES.

the blade speed should equal one-half the entering steam velocity projected
on the plane of rotation.

Considering now one pressure stage velocity compounded twice, that is,
with two rows of moving blades, it is necessary to extract all the energy from

V = steam velocity absolute at noule exit.

V = Steam Telocity alMolute at blade entrance.
Vi=: Steam velocity relative at blade entrance.
Vt=: Steam velocity relative at blade exit.
Vt= Steam velocity absolute at blade exit
u = Blade peripheral velocity in feet per second.

FIGURE 23.

Velocity Diagram for Simple Impulse, Maximiun Efl&ciency.

the steam in order to have the steam emerge from the last row of moving blades
with an absolute velocity, the component of which on the plane of rotation is
zero. Under this condition, the velocity diagram, FIGURE 24, is constructed

steam velocity at exit from tbe nosslea.

Steam velocity absolute at entrance to lat row of moving blades.
Steam velocity relative at entrance to Isl row of moving blades.
Steam velocity relative at exit from let row of moving blades.
Steam velocity absolute at exit from 1st row of moving blades.
Steam velocity absolute at entrance to guide or fixed blades.
Steam velocity absolute at exit from guide or fixed blades.
Steam velocity absolute at entrance to 2d row of moving blades.
Steam velocity relative at entrance to 2d row of moving blades.
Steam velocity relative at exit from 2d row of moving blades.
Steam velocity absolute at exit from 2d row of moving blades.
Blade peripheral velocity in feet per second.
Absolute steam entrance angle to 1st row of moving blades.
Angle of inclination of nossles to the plane of rotation.
Relative steam entrance angle to 1st row of moving blades.
Relative steam discharge angle from 1st row of moving blades.
Absolute steam discharge angle from 1st row of moving blades.

FIGURE 24.

Velocity Diagram for Velocity Compounded Pressure Stage.

with V the absolute steam entrance velocity of the first set of moving blades,
or V is the velocity acquired by the steam in the first set of nozzles. The incli-
nation of the nozzle to the plane of rotation is a, and friction is neglected. It

PRINCIPLES OF DESIGN. 33

is evident that if Vt is constructed perpendicular to the plane of rotation, in

y
order to have no component on that plane, that AB = 4w and that ^ =-7- cos a;

or, the speed of rotation is reduced one-half by the use of the principle of
velocity compounding. The velocity diagram for the second pressure stage,
with two rows of moving blades for velocity compounding, is constructed
in the same way.

In the construction of the velocity diagram for practical design, there will
be a decrease in velocity of the steam as it passes through each row of moving
blades and each row of guide blades, due to resistance from friction and shock.
This loss must be deducted from the relative entrance velocity to find the rela-
tive exit velocity in each row of blades ; or actually, for example, F2 = Fi X n,
where n is the efl&ciency of the blade passage.

The force exerted by the steam in each set of rotating blades is

where a is the acceleration of the relative steam velocities projected on the
plane of rotation. In each case this would be the siun of the comi)onents of
the relative steam velocities along the plane AB.

The indicated work done would be the product of the forces acting on
each set of moving blades and the distance u through which these forces act ; or,

Work done in foot-pounds = U!^ + ^^) X u.

The energy expended in B. T. U.'s in overcoming friction and shock in
each row of blades, moving or guide (considering that the steam velocities are
getting smaller in value as the steam flows through the blade passages), for
one pressure stage velocity compoimded twice would be, from equation (9) :

First row of moving blades: Hi= ^ — -^^^^ ^ ; (11)

First row of guide blades: k,= ^^50^''^ 5 (12)

(Y a y 2\

Second row of moving blades : Hz = ^ — Ir^^x.^ * . (13)

olXMO

The indicated work in foot-poimds for the pressure stage would also be ex-
pressed as follows :

777.5 (Hn — H^ — H, — H.) =

'''•^l^^ 50040 ■" 50040 50040 y

where H is the heat drop in the nozzles and n is the efl&ciency of the nozzles.
The theoretical action of the steam represented on the TE diagram for the
two pressure stages is shown in FIGURE 25. The heat drop in the first set of
nozzles due to expansion of the steam, or the total available heat, is 161
B. T. U/s. The expansion line a can be plotted if the eflficiency of the nozzle
is assumed to be 0.9. The steam will have a voliune of 3.7 cubic feet to each
pound upon entrance to the nozzle, and will expand through the nozzle to 26.2
cubio. feet to each poimd at the exit. The heat used in overcoming friction and
shock in the blades of the first pressiu*e stage is added to the total heat; the
increase, taking place at constant pressure, is the amount found from equations

STEAM TURBINES.

(11), (12), and (13). In this case its value is 79 B. T. U/s. The increase of

79
entropy is , or 0.118. Lay off be equal to 0.118. The voliune of

steam per pound as the steam leaves the second row of moving buckets of the
first pressure stage is, therefore, 28.6 cubic feet to each pound.

The action of the steam as it passes through the second set of nozzles and
the second pressure stage is similar to that in the first pressure stage. The
work is divided equally between the two pressure stages. The heat available

X-^l'T.

ta= 207*r.

tj=ii02*i;

26.2 <u.ft.
VZ8.6 cu.ft.

293 cu.lt.
*518 CH.ft<

TE Diagram for Two Velocity Compounded Pressure Stages.

for the second stage is increased, due to the regenerated heat from the first
stage by

hex {U — U), or by 0.118 X (207 — 102) = 12.4 B. T. U.'s.

The increase of entropy due to friction and shock of the steam passing through
the blade passages of the second pressure stage is 0.14. Lay off de equal to
0.14.

The loss of heat to the condenser will be increased due to the reheat from
friction and shock through both pressure stages by
(he + de) X {U + 460), or by (0.118 + 0.14) X (102 + 460) = 145 B. T. U.'s.

Reaction Compounding. The principles described so far have been
those that apply to the impulse turbine. The reaction compounding principle
applies to the reaction turbine of which the Parsons is the most prominent

232 APPENDIX.

As we have seen, Parsons and De Laval were pioneers in their several
spheres, but they did not block the way to further advance. Curtis ^s advance
consisted in giving to the art a device which, by its construction and mode
of operation, avoided difficulties individually incident to both Parsons and
DeLavaFs turbines. Compared with Parsons he eliminated clearances and
avoided axial thrusts; compared with De Laval he avoided the wasteful
method of creating high speed initially and neutralizing it by reducing gear,
but obtaining low speed initially, he extracted the whole working force of the
steam. As compared with both he mechanically compacted his working parts
and space into smaller compass and in his turbine disclosed a principle appli-
cable, as Parsons was, to turbines of large size, and applicable, as De Laval's
was, to those of small size. He gave the art a type of turbine which efficiently
and for the first time showed working results different from any theretofore
disclosed in the turbine art. We are clear in the conclusion that his device
was not the work of a mere constructor in his art, but that of a reconstructor,
who brought originality of conception, imlooked for and unsuspected lines
of action and creative noveltv in the disclosures he made. These features,
coupled with his departure from beaten paths, and the novel and useful results
he obtained by methods not before known, evidence the inventive nature of
his work. We have no hesitation in holding his patent valid imless antici-
pated. In the prior art we limit oureelves to the measiu*e of the scope of
alleged anticipation contended for by one of respondent's experts, who said:
** The true state of the art in 1896 is that represented by Morehouse, Harthan,
Mortier, and De Laval, plus the same developed knowledge on which Curtis
relies.'' Now there is no proof that any of these produced a practical efficient
turbine, and there is a statement by the same witness, ** I do not know that
the machines of Harthan, Toumaire, and Morehouse were ever put into prac-
tical use, nor do I know if at their respective dates the engineering knowledge
as to steam flow through nozzles, etc., was adequate to permit successful
practical use of these machines," which virtually admits they did not. A
British patent. No. 144 of 1858, followed by an American one, was granted
to the Harthans for a motive power engine to be worked either by air or steam,
** whereby the expansive and reactive force of the propelling mediiun
is brought into play." A study of this patent shows that the Harthans did
not purport to disclose any new principle of operation, but their device was
based on the form of their buckets and the general arrangement of their
machinery. If those features involved any new principle of operation the
patentees neither knew nor claimed it, or indeed, anything save their peculiar
bucket form, for they say:

** We are aware that rotary engines, consisting of wheels having a
number of projections formed or fitted into their peripheries and actuated
by the impingement of steam or air against such jDeripheral projections
or chambers, have long been known in this country, and therefore we lay
no claim to the principle of such arrangement .... but what we consider
to be novel and original and therefore claim .... is, fiLrstly, the system
or mode of obtaining motive power by causing steam or air to impinge
upon a series of chambers with curved bottoms arranged round a wheel,
at or near the periphery thereof, as herein described."

FIGURE 26.

Reaction

^^rrrin

Velocities

Pressures

PRINCIPLES OF DESIGN. 35

representative. In this turbine there are alternate rows of guide and moving
blades. The guide blades are attached to the casing; the moving blades are
attached to the rotor which is in the form of a drum attached to a shaft, as in
the impulse turbines already dealt with. The steam expands continuously ,.

from boiler pressure to condenser pressure from the entrance to the first row |l

of guide blades to the exit from the last row of moving blades. The steam thus
acquires a gradually increasing velocity due to its expansion, part of this
velocity being absorbed by each row of rotor blades as it passes through them.
If the rotor were prevented from moving and the steam allowed to flow through
the turbine, the blade passages taken together would constitute a large expan-
sion nozzle and the steam velocity would increase continuously from beginning
to end.

The steam flows through the first row of guide blades g, FIGURE 26, with
a small amount of expansion and acquires an initial velocity. It then fiows
into the blade spaces of the first row of rotor blades w, expanding still more
and acquiring a further increase in velocity which is partially absorbed by
the first row of rotor blades. The steam continues to flow in the same manner
through each succeeding pair of blade rows, giWi, g2W2, and is gradually reduced
in pressure a few pounds step by step through each pair of blade rows. The
voliune of steam increases as the pressure falls.

The velocity curve show^s a slight increase in velocity through each row of
guide blades, and a slight decrease in velocity through each row of rotor blades,
due to the fact that the rotor blades absorb the velocity. These velocities are,
of course, all absolute velocities.

The pressure curve shows a gradual decrease of steam pressure towards
the condenser pressure, the pressure at all points in the blade passages being
higher than the turbine exhaust pressure. As the pressure on the entrance
side of a row of blades is greater than the pressm'e on the exit side of the
same row of blades, there will necessarily be a small amount of steam leakage
over the tips of the blades. This steam leakage is called ** tip leakage ^' and
leads to the necessity of constructing the reaction turbine with as small an
amount of tip clearance as will be consistent with safe running.

STEAM TURBINES.

With the simple reaction turbine it is necessary for the relative steam
entrance angle to be 90° in order that there will be no impulse. In order to
extract all the energy from the steam it should emerge from the moving blades
with an absolute velocity, the component of which along the plane of rotation
is zero. Under these conditions the velocity diagram, FIGURE 27, is con-
structed with V the absolute entering velocity, u the peripheral velocity of the
moving blades, Vi the relative entering velocity, b the relative steam entrance
angle = 90°, and Vs the absolute exit velocity. Then the absolute exit velocity
Vs has no component along CB. It is evident that

CB = u, and that u = V cos a,

where a is the absolute steam discharge angle from the first row of fixed
blades. The condition of maximum efficiency is, therefore, for a simple reac-
tion turbine, that the peripheral blade speed should equal the component of
the entering steam velocity along the plane of rotation.

V = steam Telocity at exit from the Ist row of guide
blades.

V = Steam velocity abaolute at entrance to moving
blades.

^ Vi = Steam velocity relative at entrance to moving

bladea.
Va= Steam velocity relative at exit to moving blades.
yt= Steam velocity absolute at exit to moving

blades,
u = Blade peripheral speed in feet per second,
b = Relative steam entrance angle.

FIGURE 27.

Velocity Diagram for Simple Reaction, Maximiun Efficiency.

In order to reduce peripheral speed of the rotor to practical limits, the
expansion in the compound reaction turbine is carried through many rows of
guide and rotating blades. There may be consecutive rows all of the same
diameter followed by others of greater diameter as the required volume for
the passage of the steam becomes greater and greater. Each row of blades,
either guide or rotating, is in fact a pressure stage, but for convenience of
design each pair, made up of one row of guide blades and one row of moving
blades, is called a stage. Each group of rows of the same diameter or the same
height is called an expansion.

The velocity diagram for one expansion is shown in FIGURE 28. Assum-
ing that the diameter of the rows of blades is constant, the peripheral velocity
of all rotating blades will be the same. Let this value be called u. The
diagram is constructed for constant conditions of absolute and relative veloci-
ties throughout the various stages; that is, F=Fa = F4 = F6 and Fi = F3
= Fb = Ft. Values on the diagram are assigned for convenience of compari-
son. The steam expands in the first row of guide blades and attains a velocity
V with which it enters the first row of moving blades.

PRINCIPLES OF DESIGN.

The force exerted by the steam on each row of moving blades is F= -^ ,

where a is the acceleration of the relative steam velocities projected on the
plane of rotation. In each case this would be the smn of the components of
the relative velocities along the plane ahc, or a = (ba + ac)j and

F = J^(ha + ac).
9
The indicated work done for each row of moving blades would be the

product of this force and the distance w through which this force acts; or,
Work done in foot-pounds on each row of moving blades = — {ha + ac) X u.
The indicated work done on both rows of moving blades of this expansion

would be

It will be noted
that the steam ex-
pands through the
blade spaces of both
'the guide and the
moving blades. These
blade spaces are there-
fore steam nozzles and
may be treated as such
in obtaining the value
of the indicated work.
In the first row of
guide blades the veloc-
ity increases from
zero to V; in each row
of guide blades after
the first the velocity
increases from Vs to
V; in each row of
moving blades the
velocity increases
from Vi to V. The
indicated work in
f oot-poimds could
then be expressed as
follows for one poimd
of steam :

(ha + ac) X u.

K^'^^^^

V = Steam Telocity at exit from let row of ^Ide blades.

V = Steam velocity absolute at entrance to 1st row of moying blades.
Vi= Steam velocity relative at entrance to Ist row of moving blades.
Vt= Steam velocity relative at exit from 1st row of moving blades.
Vs= Steam velocity absolute at exit from Ist row of moving blades.
Vs= Steam velocity absolute at entrance to guide or fixed blades.
V«= Steam velocity absolute at exit from guide or fixed blades.

V4= Steam velocity absolute at entrance to 2d row of moving blades.
Vs= Steam velocity relative at entrance to 2d row of moving blades.
V«= Steam velocity relative at exit from 2d row of moving blades.
Vt= Steam velocity absolute at exit from 2d row of moving blades,
u = Blade peripheral velocity in feet per second.

FIGURE 28.

Velocity Diagram for a Reaction Expansion.

First row of guide blades : 777.5 X fl^i, where B.^ =
Each row of guide blades after the first : 777.5 X If », where Ht =

Each row of moving blades : 777.5 X B.%^ where B.t =

50040 '

50040 '
(F* — F.*)
50040 •

The absolute steam velocity from the last row of moving blades is Vt. This is

38 STEAl^I TURBINES.

residual velocity which does no work in this expansion. The work lost is
equal to

^'* X 777.5 = ^foot-pounds.

50040 2g

The total work done by the expansion per pound of steam is

777.5 {Hi + H^ + 2Hz) — ^foot-pounds.

The total useful heat is (-ffi + -Er2 + 25^8), and the total heat required for this
expansion for each pound of steam is

(gx + H. + 2g,)
n

where n is the efficiency of the expansion.

The theoretical action of the steam represented on the TE diagram for
two stages of an expansion is shown in FIGURE 29. Due to the fact that the
steam enters the first row of guide blades with initial velocity of zero and must
acquire a velocity of 1800 feet per second upon exit, there will be a greater
heat drop in the first row of guide blades than in the succeeding ones which
expand the steam to the same velocity, but from an initial velocity of 787
feet per second. With an efficiency of 0.7 throughout the expansion, that is, a
heat loss due to friction and shock of 0.3, the expansion line may be plotted.
The heat necessary to create the exit velocity of the first row of guide blades
from equation (9) will be

^' ^ 50040 X .7 = 50040 X .7 ^ ^^'^ ^' ^' ^•'^'

The heat expended in each row of moving blades and in the second row of
guide blades from equation (10) will be

y»_y,» _ (1800)-- (787)' _^^g3B ^ ^,
^ 50040 X. 7 - 50040 X .7 ^^"^ J^. l. U. s.

Principles Used in Marine Turbines. Turbines as used in the Naval Ser-
vice are the main turbines used for propulsion, and smaller turbines used for
diiving auxiliary machinery, such as pumps, blowers, and generators. The
small size turbines are constructed on one or two of the impulse principles.
Types of these turbines will be described in a later chapter. The main turbines
are constructed on the pressure compounding impulse, pressure velocity com-
pounding impulse, and reaction compounding principles. In impulse turbines
the first few pressure stages are usually velocity compounded, the succeeding
pressure stages being constructed with but one row of moving blades to the
stage. A later development of the turbine combines at the high-pressure end
an impulse pressure stage, usually velocity compounded, with a number of
reaction expansions following to the turbine exhaust. In this case the turbine
is known as a " mixed '^ or " combined '' turbine, for the reason that the basic
principles of impulse and reaction are combined in the same turbine.

PEINCIPLES OF DESIGN.

„of lao lbs.ab&|/cu. ft.

lOtf

FIGURE 29.

TE Diagram for a Reaction Expansion.

CHAPTER VI.
BLADES.

Purpose. Blades attached to the rotor serve the purpose of imparting
motion to the rotor and to the rotor shaft. They are the direct agents for
converting the kinetic energy of the steam into mechanical energy,

Blades attached to the casing and called guide or fixed blades serve the
purpose of guiding the steam in the correct direction in order that the steam
may impart its force against the moving blades in the direction of rotation.
In the reaction turbine the guide blades serve the additional piu^pose of
expanding the steam; and in the impulse turbine, where drum construction
of rotor is used, the guide blades for the stages in wake of the drum serve
the purpose of expanding the steam.

Buckets. The shape and design of blades on the rotor and on the casing
are the same. The face of one blade and the reverse side of the adjacent blade
together form a bucket, passage, or space through which the steam flows.
The conversion of the kinetic energy of the steam into mechanical energy
takes place within the moving buckets. The bounding surfaces of the buckete
control the direction of flow of the steam.

Requirements. The blades must be so formed and manufactured that
the steam will give the required results with a minimum loss from shock,
eddying, and friction.

Material Blades are made of:

1. Bronze which has been extruded through a die of proper shape
to give the blade the correct cross-sectional shape, the metal being forced
out of the die in a long bar which is then cut into pieces of the proper
length for the blades which are machined where necessary.

2. Nickel steel machined from solid nickel steel bar.

3. Steel stamped from steel strip and machined where necessary.

4. Other different alloys stamped or machined to shape.

5. Steel which is a part of the turbine wheel, the blades being milled
to shape by a special tool in the case of small turbines.

Impulse Blades. The shape and cross-section of the impulse blade is
determined by the necessity to maintain steady flow of steam with a minimiun
amount of loss from eddying, shock, and friction.

In order that steady flow of steam may be maintained through the bucket,
impulse blades should be thickened at the center, otherwise the cross-sectional
area of flow will be greater at the center than at the entrance and exit of the
bucket and will leave an eddy space at this point. If the blades are of constant
parallel section, as in FIGURE 30, this eddy space is shown at a. This space
might also cause local expansion of the steam. The blade is therefore thick-
ened at the middle in order that the cross-sectional area of the steam as it
flows through the buckets will at all points be the same.

42 STEAM TURBINES.

With high velocities of steam that sometimes obtain in the first velocity
compounded pressure stage of an impulse turbine, the centrifugal action of
the steam due to timiing may cause the steam to compress at the point of

turning leaving an eddy space
at a, FIGURE 31. It is there-
fore necessary in this case to
still further thicken the blades
■ at this point of turn, as shown

in nCURE 32.

Assuming that shock is to

be avoided, the inlet angle of

the blade will be determined by

the velocity and direction of

_______ - - steam flow relative to the plane

XT -X J! mv . , ■ X ' 1 T.1 J of rotation, combined witi the
Necessity for Thickenmg Impulse Blades ^^^^ peripheral blade veloc-
at the Center. ■, *», I • ^i. , , ,

ity ; that is, the blade entrance

angle will in this case be equal to the angle that the steam velocity, relative
to the moving or rotor blades upon entrance to the buckets, makes with the
plane of rotation. In FIGURE 33, let V represent the absolute velocity and
direction of the entering steam and u the peripheral blade velocity and direc-
tion of rotation. The velocity and direction of the steam relative to the

FIGURE 31. FlGXmE 32.

Compression of Steam Thickening of Impulse Blades

at the Turn. to Allow for Steam

Compression.

buckets will be Vi. The inlet angle of the bucket in order to avoid shock
should therefore be ai, the same value as the relative steam entrance angle.
The width of the entering steam is a.

If the steam is entering fixed or guide blades, the blade entrance angle
is determined by the direction of absolute velocity of steam discharge from
the preceding row of rotating buckets. This is the entering velocity and
direction of the steam for the guide buckets relative to the guide buckets.

If the inlet angle is made too small, there will be a loss from shock and
eddying, and in the case of the moving buckets an impulse is given in the

BIADES. 43

reverse direction to that of rotation; that is, the steam will discharge against
ab, FIGURE 34, where ^ is the blade entrance angle and a is the relative
steam entrance angle.

The exit blade angle, at, FIGURE 33, is determined by the relative direc-
tion and velocity of the steam as it leaves the buckets. If the velocity diagram
is completed in this figure, u representing direction and velocity of the bucket
periphery, then Vi is the direction and value of the exit velocity relative to
the rotating blades and V. is the absolute steam exit velocity. The width of
the steam as it leaves the buckets is b, and is equal in this case to the width

*« ^B..

-'•'--e'^^-.

T la tbc nonle itMin t
Ti ta Um niattn iteui

Oi U tbe relatire iteam

a, I* the bUde entrmDci

• la th« wldtb of the b
b la the width Dl tbe b
V( la tbe ttrnn exit tfIi
Ti la tbe iteam exit rel

exit velocltr.
m ■■ the wldtb or the b
k 1> the wldtb of the b

* 1< the aosle of tnro <
n la the peripheral ape
a, to tbe reUUve atean

FIGURE 33.

Impulse Blade with No Shock.

a at the turn. In order that the steam may be properly guided as it leaves
the buckets, that is, that the width b may not be exceeded, the face of the
blade for a short distance at f is made parallel to the back, dh, of the adjacent
blade.

The angle of turn of the steam is 6, FIGURE 33, and is the angle through
which the steam is turned in passing through the bucket. The smaller the
entering and exit angles are made, that is, the gi'cater the value of the angle
of turn, the greater will be the energy extracted from the steam in passing
through the buckets, due to the fact that the component of the velocity on
the plane of rotation is greater. But on the other hand, the bucket will be

44 STEAM TURBINES.

lengthened and the frietional losses will be increased. The best angle for
entrance and exit, as determined by experiment, is between 25° and 30°, but
in velocity compounding the angle of the first row of moving blades will
generally have to be less than this.

The inlet edges of the blades should be sharp for they must split the steam
as it enters the buckets. The exit edges of the blades should also be kept as
fine as possible to avoid eddjdng as the steam leaves the buckets. This will
be seen by referring to FIGURE 35, where the blades are left thick at the
discharge edge, leaving spaces a into which the steam will spread. The blades
for the turbines of the NEVADA have the edges roimded with a radius of
0.0075 inch.

In order to prevent the steam from discharging against the back of the
blade, as in FIGURE 34, and to reduce skin friction by shortening the steam
channel, the inlet angle of the blades is sometimes made larger in practice
than is required by theoretical calculation. The loss from shock as the steam
enters the buckets, due to increasing the blade entrance angle, seems to be
more than coimterbalanced by the reduction in skin friction, due to shortening
of the steam channel. In addition to this, the blade width is decreased, which
means considerable reduction in the length of a large turbine. FIGURE 36
represents a bucket designed for a blade entrance angle P, 30° greater than
the steam entrance angle ai. The blade is said to have an entrance angle with
30° shock. The width k is reduced considerably from the corresponding dimen-
sion of FIGURE 33, which represents similar blades with no shock.

BLADES.

FIGURE 34.

Blade Entrance Angle Too Small.

FIGURE 36.

Blade Edges Too Thick.

FIGURE 36.

Impillse Blade with 30° Shock.

STEAM TURBINES.

Reaction Blades. The shape of the cross-section of the reaction blade is
determined by the necessity to expand the steam in the smoothest way possible
without eddying, shock, or excessive friction losses.

The entrance angle, instead of being determined by the relative steam
entrance velocity, is made larger than the relative steam entering angle and,
therefore, is by no means arranged to avoid shock as the steam enters the
buckets. The reaction blade is shown in FIGURE 37 with the velocity diagram
drawn as for the impulse blade. The relative steam entrance angle is ai. The
blade entrance angle is P, which in this case is equal to 90°. The construction
of the blades as shown dotted would be for no shock; hence, it is seen that
if the blades are made for no shock, the steam channel would be increased in
length and the losses from friction would be considerably increased. Results

4r- ^

-e

V is the guide blade steam exit velocity.
V] is the steam velocity relative to the moving blades.
ai is the relative steam entrance angle.
is the blade entrance angle =90*.
a is the width of the band of steam entering the blades,
b is the width of the band of steam leaving the blades.
Vf is the steam exit velocity relative to the blades.

Vt is the steam exit velocity relative to the casino, or is the absolute exit velocity,
k is the width of the blades in the direction of the turbine axis,
u is the peripheral speed of the blades, or speed in feet per second,
oais the relative steam discharge ang]e=the blade discharge angle.
$ is the angle of turn of the steam = 180 * —(oi+o,).

The dotted lines represent the same blades constructed for " no shock ** ; that is.
if fi were decreased in value to equal Ox.

FIGURE 37.

Reaction Blade with Entrance Angle of 90°.

appear to show that the losses from shock due to enlarging the blade entrance
angle are more than counterbalanced by the reduction in friction due to
shortening the steam channel.

As the buckets are practically steam nozzles in which expansion of the
steam takes place, the blades need have no thickness; but for purposes of
strength the blades are thickened at the middle, as shown in FIGURE 37.

The smaller the exit angle is made the greater is the peripheral component
of the discharge velocity. This is the only component available for useful
work in the rotating buckets. When the discharge angle is very small the
steam channels become long and extremely narrow at the exit, thus causing
large friction losses. The exit angle is accordingly made to be about 20°.

BLADES. 47

The same considerations which govern sharpness of entrance and exit
edges of impulse blades make it necessary to have edges of the reaction blades
as sharp as is consistent with strength of material.

The width of the entering jet of steam is a; of the leaving jet is b. The
ratio between these two dimensions is usuallv

^ =2 to 3.
h

Blade Annulus Area. The relation between the width of the buckets at
the exit to the width of the exit steam path is expressed in FIGURES 33 and 36
by equation :

b = m sin a>, or t// = - — ,

, sm 0.2

where

h is the width of the steam jet from one bucket,

in is the ^^idth of the exit area of a bucket,

ai is the })lade discharge angle,

and the assumption is made that the reaction blade has no thickness and that
the edges of all blades have no thickness. Actually, reaction blades have a
certain thickness and the edges of all blades have a certain thickness. This
thickness will decrease the bucket exit A\ddth from 8 to 15 per cent depending
on the blade exit angle.

The ratio between the total bucket exit area and the total exit steam jet
area foi* one row of blades is

ni __ J^

b f sin a2 '

where / is a thickness factor determined for each row of blades. If the weight
of steam passing per second, specific vohune of the steam, and velocity of
steam exit in feet per second be known, then

(Specific volume) X weight X 144

Cross-sectional area of steam
exit in square inc^hes

and

^, , 1 (Specific vohune) X weight X 144
Blade annulus area = — — — -r-^ — ;

VXfXsma2

Blade Height. If the mean diameter of the blade annulus is D inches,
then

Blade height = /. =:^^^^^^^^^^-^'^^

Rotor diameter = Z> — h, and diameter of blade tips = D + h.

Securing Blades. The methods of securing blades to the rotor and the
casing will be taken up in the description of each type of turbine.

CHAPTER VII.
MARINE TURBINE CONDENSING PLANTS.

Neceuity for High Vacuua. Theoretically, as well as practically, the
efficiency of the marine turbine is greatly increased by an increase in the
percentage of vacuum in the condenser, or by a decrease in the exhaust pres-
sure. The reason for this increase of efficiency is that the turbine is admirably
adapted to the use of low-pressure units and large exhaust pipes that will
allow the steam to be expanded to large volumes corresponding to pressures
as low as 0.7 of a poimd per square inch absolute, or to a vacuum of about
95 per cent (28.5 inches).

Reasons for the Development of Modem Condensing Plants. As the neces-
sity for higher vacuua than about 88 per cent has never arisen with recipro-
cating engines, owing to the fact that lower pressures than 1.8 pound per
square inch absolute would necessitate expanding steam to such a volume
that the size and weight of the L. P. cylinder would be prohibitive, the
condenser for a reciprocating engine was designed to give the required
vacuum without any gi'eat difficulties as to size and weight. But for marine
turbines it is of the utmost importance to so design the surface condenser as to
fulfil the condition of a high vacuum and still keep the condenser within
practical limits of size, weight, and space occupied. Hence, with the advent
of the marine turbine, more attention has been paid to the design of the
condensing plant, with the result that there are various installations now in
use peculiarly well adapted to meet the needs of the turbine.

Limit* of Expansion of Steam. To expand steam from 200 pounds per
square inch absolute to one poimd per square inch absolute, at which points
steam has a specific volmne of 2.29 cubic feet and 333 cubic feet respectively,
the volxune must increase about 145 times. To carry the expansion to this
point, in the reciprocating compound engine, the cylinder ratio would have
to be about 44 to 1. The diameter of the L. P. cylinder would have to be
about 6.6 times that of the H. P. cylinder. This is an impracticable size
for the L. P. cylinder on accoimt of weight and space occupied. On the
other hand, in the case of the turbine the steam may be easily expanded 150
times without encountering difficulties.

Work Done Compared on the PV Diagram. The comparison of work
done by the turbine by expanding steam to a low pressure with that done by
the reciprocating engine by expanding the steam to a pressure within practical
limits is illustrated in the PV diagram, FIGURE 38. One pound of steam is
expanded from an initial pressure ab in both the turbine and the reciprocating
engine. The expansion line is hex. At point c expansion has been carried
as far as the size of the L. P. cylinder permits. The exhaust valve opens,
hence c is the point of release. The pressure then drops from c to d with
constant volmne. The condenser pressure is ed. The section of the diagram
marked abcde represents the theoretical value of the energy of the steam
converted into work by the reciprocating ei^ine operating against a back-

STEAM TURBINES.

pressure of four pounds per square inch absolute, or a vacuiun of about
22 inches. This back-pressure is represented by ed. If the back-pressure is
now reduced to two pounds per square inch absolute, the gain in power for
the reciprocating engine would be due simply to the reduction in back-pressure
represented by the hatched area having the length p on the diagram. This
is but a small percentage of the total area of the diagram, abcde. By designing
the point of release to come further along the expansion line, a further increase
in power could be obtained, but this is impracticable with the reciprocating
engine for the reasons already given, increased volume of the L. P. cylinder
beyond practical values of size and weight.

p ^^ --t ---

FIGURE 38.

PV Diagram for Turbine and Reciprocating Engine.

With the turbine, expansion may be carried further, as it is an easy
matter to enlarge the volume of the L. P. blade spaces, or buckets, to take
care of the increasing volumes of steam due to its greater expansion. At the
same time, with the turbine, work is extracted from the steam up to the point
of exhaust from the last row of L. P. blades. In the diagram, FIGURE 38,
expansion in the turbine may be carried to two pounds per square inch abso-
lute, or to the point x of the expansion line. The gain in power of the turbine
operating with a vacuima corresponding to this pressure over a reciprocating
engine operating with a back-pressure of four pounds per square inch absolute
is represented by the sum of the hatched section having the length p and
the hatched section having the length L The gain in power of the turbine

MARINE TURBINE CONDENSING PLANTS.

over the reciprocating engine, where both are* working with a condenser pres-
sure of two poimds per square inch absolute, is represented by the hatched
area having the length t.

Woric Done Compared on the TE Diagram. In FIGURE 39 the gain
in power of the turbine operating with a low condenser pressure is shown on
the TE diagram. The expansion is assumed to be adiabatic. Area abcde
represents the energy utilized by the reciprocating engine expanding steam
from pressure (or temperature) ab to a back-pressure ed of four pounds per
square inch absolute. The point c is the point of release, from which the
steam pressure drops to d with constant volume.

FIGURE 39.

TE Diagram for Turbine and Reciprocating Engine.

The area abke represents the energy utilized by the turbine operating
between the same pressures. This shows a gain over the reciprocating engine
of work done in B. T. U.^s equal to area ckd.

If now the condenser pressure for both reciprocating engine and the
turbine is reduced to two poimds per square inch absolute, or to gfli, the gain
in energy utilized in B. T. U.^s would be for the reciprocating engine edfg,
and for the turbine ekhg. The gain for the reciprocating engine, edfg, is
but a small proportion of the area abcde; while the gain for the turbine,
ekjhg, is a considerable part of the area abke.

For the reciprocating engine to gain materially in efficiency by using
a high vacumn, it is evident that the release point c must be lowered. This
means an increase of the volume of the exhaust steam, and hence an increase
in the size and weight of the L. P. cylinder beyond practical limits.

52 STEAM TURBINES.

Failure of the Vacuum. For the same reason that the turbine increases
its power due to a high vacuum, failure to obtain the designed vacuum will
result in a falling off in power developed. This will be much more serious
in the turbine than in the reciprocating engine. This fact is well illustrated
in the case of turbine powered torpedo-boat destroyers operating in the tropics
with a temperature of circulating water in the condensers of 80° to 85°. The
falling off in vacuiun is from two to four inches, with a consequent serious
reduction in speed of the destroyers resulting from the failure to obtain the
designed power from the turbines.

Percentage of Gain for Turbines by Increase of Vacuum. In practice,
the gain in economy due to increasing the vacuum for turbines from 26 to
27 inches is about 5 to 6 per cent; increasing from 27 to 28 inches, about
7 per cent.

Mechanical Parts of a Condensing PlanL The condensing plant for
the turbine consists of the condenser, the circulating pump for circulating
cooling water through the condenser, the air and water removal pump or
pumps, and a feed tank into which the water of condensation is discharged
from the air-pump and stored for further use in the boilers.

Surface Condenser. The surface condenser is the type of condenser used
for marine purposes. It consists of a chamber or shell containing a number
of composition tubes through which the circulating water passes. The steam
condenses on the outer surfaces of the tubes. The water of condensation is
pimaped by the air-pmnp to the feed tank. The air is reduced in volume by
cooling and is removed by the air-pump. The latent heat of the steam at
condenser temperature and the heat removed from the air is transmitted
through the tubes to the circulating water, the temperature of which is thereby
raised. ^

The munber of B. T. U.'s of heat carried away by the circulating water
from each poimd of steam used in the turbines, assmning adiabatic expansion
to have taken place in the turbine operating between 200 pounds and one
poimd per square inch absolute is

B. T. U.^s = 1.413 (460 + 102) = 794.1,

where 1.413 is loss of entropy at 102^F. and (460 + 102) is the absolute
temperature of the exhaust steam.

Requirements of a Condensing Plant The requirements of a condens-
ing plant for marine turbines are the following:

1. Reliability.

2. Simplicity.

3. Ability to maintain the designed vacmun at all times.

4. The total weight and the space occupied to be within the practical
requirements of ship construction.

5. Greatest possible efl&ciency of condenser cooling surface.

6. Rapid and complete removal of air and of water of condensation
from the condenser.

7. As high a temperature of water discharged to the feed tank as is
consistent with maintaining the designed vacuiun.

8. Economical operation of pumps; or, the high vacuum must be
obtained without an excessive expenditure of steam.

MARINE TURBINE CONDENSING PLANTS. 53

Condeiuen for Turbine InstallatitHU. The necessity for high vacuua to
give high efficiency of marine turbines has resulted in the development of
condensers that meet the requirements of the preceding paragraph. Descrip-
tion will be limited to these types, as information in regard to the ordinary
cylindrical marine condenser may be found in text-books on the reciprocating
engine.

Weir Uniflux Condenser (FIGURE 40). The main features of this
condenser are the shape of the cross-section, the spacing of the tubes, the size
of the steam opening, the bottom baffle-plate, and the vertical plates supporting
the shell.

The transverse section A decreases in area from the steam entrance to
the air-pump suction to reduce weight by allowing just sufficient volxune for

FIGURE 40.

Weir Uniflux Condenser.

the steam as it is condensed to water in passing through the condenser. This
insures constant velocity of steam through the condenser.

The tubes are spaced further apart at the top or entrance to the condenser
than at the bottom, to allow for the larger volume of steam at the entrance
before condensation starts.

The steam discharge from the turbine extends the whole length of the
condenser. This not only gives a very easy flow for the entering steam, but
also allows it to discharge equally over all the tubes, using to fuU advantage
the whole cooling surface.

A baffle-plate, B, pierced with a nxunber of holes is arranged immediately
under the bottom row of tubes. This prevents the main flow of steam being
direct to the air-pump suction, and consequently prevents the end portions of
the tubes from not being used effectively.

The shell is supported at the sides and top by the vertical plates P which
are arranged parallel to the direction of the steam flow. These plates are

STEAM TURBINES.

riveted to the shell and do away with stay bolts, eliminating possible sources
of air leakage where the stay bolts would pierce the shell.

Contraflow Condenser (FIGURE 41). This condenser is of the same
shape as the uniflux condenser, but possesses the additional feature of baffles
to guide the steam through the condenser. As the steam enters the condenser
with considerable velocity, the kinetic energy is utilized to deflect the steam
current towards the air-pimip suction. Plates P are provided to promote a
uniform distribution of steam entrv. Plates B direct the lines of flow towards
the narrow longitudinal channel formed by baffle C and the sides of the
condenser. The effect is to compress the air into the air-piunp suction A,
and thereby to permit the air-piunp to maintain in its suction a minimum of

mMtr^lMNr/

FIGURE 41.

Contraflow Condenser.

FIGURE 43.

Parsons Augmenter.

air-pressure. Consequently, the weight of air normally contained in the con-
denser and the air insulating effect on the efficiency of heat transference are
reduced.

Bent Tube Condenser (FIGURE 42). The cross-section of this con-
denser is oval in shape, though the cylindrical cross-section is not unusual.
The tubes are expanded in both tube sheets. To allow for their expansion
when heated, the tubes are bent. When they expand, they take on a curvature
of smaller radius. The steam exhaust pipe from the turbines is braced (not
shown) instead of being supported by plates.

The condenser is provided with a system of baflfte-plates for the purpose
of separating the air from the vapor and condensed steam as it flows towards
the air-pump suction. Two horizontal solid baffle-plates A and B run the
whole length of the condenser, but are cut away on the side opposite to and

MARINE TURBINE CONDENSING PLANTS. 55

on the end nearest to the wet and dry air-pump suctions, so as to provide a
passage for the air and water. To reduce radiation of heat from the water
that collects on top of plate A to the air which is being cooled in the lower
part of the condenser, the bottom of plate A is provided with a vacuum
chamber. Whatever water collects on top of plate A is drawn off by a pipe
P connected through a water seal to the wet air-piunp suction W. A vertical
baffle-plate C, between baflBes A and B, extends beyond mid-length of the
condenser and serves to direct the air caught between plates A and B to flow
through the nest of tubes under plate A and to the left of plate C, thence
through the nest of tubes under plate A and to the right of plate C, to the
dry air-pump suction R. Perforated baflle-plate D also extends to the middle
of the condenser for the purpose of screening the wet air-pump suction.

Air-Pumps. The term ** air-pmnp ^' is applied to the pumps used for the
removal of both air and water from the condenser. Where pumps are installed
to perform the separate functions of air removal and water removal, they are
called respectively ** dry air-pump '^ and ** wet air-pump. '^ The suction of
the dry air-pump, where such is installed, is above the suction of the wet
air-pump.

Air-Pumps for Turbine Installations. Since the marine turbine has come
into general use, various systems for creating and maintaining high vacuua
have been developed. These systems may be classified as follows:

1. Steam jet or steam and water jets working alone or in connection
with rotary or reciprocating pumps, examples of which are:

(a) The Parsons augmenter.

(b) The kinetic system.

(d) The Morison air ejector.

2. Wet and dry air-piunps, either rotary or reciprocating, examples
of which are :

(a) Weir dual air-pump.

(b) Blake twinplex pump.

3. Rotary pumps, an example of which is:

(a) LeBlanc rotary piunp.

The Parsons Augmenter (FIGURE 43). The air and uncondensed
steam are extracted from the condenser through the suction-pipe attached to
the bottom of the condenser. They are compressed by a steam jet in a con-
tracted pipe to about half their bulk. They are then delivered to the air-piunp
at a pressure about two inches higher than the pressure in the condenser
through the augmenter condenser which has from 2 to 3 per cent of the cooling
surface of the main condenser. In this augmenter condenser the air is cooled
and reduced in volume, and the steam is nearly all condensed before it enters
the air-pump. By the extraction of practically all the air from the condenser
by the steam jet, the conductivity of the cooling surface is much increased.
The steam used by the jet is about 0.6 per cent of the steam used by the turbine
plant at its normal full load. Water of condensation flows by gravity from
the condenser to the air-pump suction. The air-pump used may be one of
standard make, but the augmenter is usually installed with a compoimd pump
designed for the purpose.

56 STEAM TURBINES.

Kinetic Syitem (FIGURE 44). This system consists of three rotary
piunps, a steam jet, and a water jet. The steam jet 2 is supplied i\-ith steam
from exhaust pipe IS. Its suction from the condenser is at 1, above the water
suction. This jet acts on the same principle as that of the Parsons augnienter
in removing air and uncondensed steam from the condenser and condenses
them in pipe 3, from which it is further removed and condensed by the water
or kinetic jet 4. The kinetic jet is supplied with ejection water by the kinetic
pump 17 which draws water from the tank 13 through pipe 5 and discharges
it through pipe 6 which is therefore under pressure. The water of condensa-
tion is removed from the condenser by two rotary pumps 18 and 19. The

FIGURE 44.

Kinetic System.

head pump 18 works imder the condenser pressure both on the suction and
discbarge sides. It removes the water through suction 7 and discharges it
through pipe 8 to the pressure pump 19. This in turn discharges the water
through pipe 9 and cheek valve 10 to the tank 13. A head of pressure is
provided for the pressure p\mip 19 by using the stand pipe 8 connected to
the condenser by the pipe 14, for the head pump 18 to discharge into. This
arrangement makes it possible to place these pmnps only a few inches below
the condenser bottom. When the water in the tank 13 rises above a certain
level, the float 20 rises and opens a valve 21 on the pipe 11, which is connected
to pipe 6 inside the tank, and allows the water to flow through pipe 11 into
the feed tank. The steam used in the steam jet 2 raises the temperature of
the feed water and in this manner indirectly increases the efficiency of the
steam jet.

FIGURE 42.

Bent Tube Condenser.

Exhaust Steam Inlet

MARINE TURBINE CONDENSING PLANTS.

Westinghouse Air Ejector (FIGURE 45). The air is removed from the
condenser by an air ejector of special design operated by live steam. Live
steam of any pressure available from the boilers enters the ejector, which
acts as a dry vacumn pump, and withdraws the air from the condenser. Tlie
discharge from the ejector is into an air-separating tank. The water removed
from the condenser by the centrifugal piunp is discharged into the air-sep-
arating tank. This water condenses the steam discharged into the air-sep-
arating tank from the ejector, raising the temperature of the water in this
tank. The air removed from the condenser escapes from this tank to the

Ctrculating Pipe

Overflow

UofleufhanZft.

CondensaH

Pump •*'

FIGURE 45.

Westinghouse Air Ejector.

atmosphere through a vent pipe arranged on top of the tank. The water from
the air-separating tank flows by gra\ity to the feed tank.

A circulating pipe connects the feed tank and the condenser. The purpose
of this pipe is to allow water to flow back to the condenser from the feed tank
when very little steam is entering the condenser. This always gives the air-
separating tank a sufficient supply of water to condense the steam from the
ejector, and at the same time prevents an abnormally high temperature of
feed water by cooling part of the feed water as it circulates through the
condenser.

The air ejector is shown in FIGURE 46. The group of steam nozzles
operating the ejector is shown in FIGURE 47.

58 STEAM TURBINES.

MorUon Air Ejector (FIGURE 47a). This system eoiiipi-ises a two
cylinder reciprocating pmnp and a steam ejector. Condensed water is
i-emoved from the condenser A by a wet pmnp B and delivered to the feed
tank. The steam ejector C removes air from the condenser at a suction abo\e
the water suction. This ejector C discharges steam and air into heater D. A
pipe E led from the pump discharge of B sprays water into the heater D and

fafx^r Sue t, on

FIGURE 46.

Details of Ejector.

FIGURE 47. FIGURE 47a.

Air Ejector Steam Nozzles. Morison Air Ejector.

condenses the steam from ejector C. Water from D is led into the dry air-
pump barrel F, through pipe G and a non-return valve. The air from the
heater D is removed by the dry air-pump F through pipe H connected to the
dry air-pump suction. Pump F discharges to the feed tank. The pii>e J
supplies water either from the pipe E or from the feed tank for the pui'pose
of cooling air from heater D. This water also acts as sealing water for pump
F. The air is compressed into the heater D into from one-thii'd to one-half
of its original volimie.

MARINE TURBINE CONDENSING PLANTS. 59

Weir Dual Air-Pump (FIGURE 48). This system consists of two ver-
tical pumps worked from one steam cylinder. The wet air-pmnp is A and
the dry air-pmnp is B. In all cases, the wet air-pmnp is situated below the
steam cylinder, as this pvanp is the only one which works under any consider-
able load. The dry air-pump is driven by the beam and 1i"k« in the usual
manner.

One connection, C» is made to the condenser, but a branch pipe D is led
from it to Hie dry air-pump, the connection being so made that the water will
all pass D and flow to the wet pump. Both pimaps are generally of the three-

Talve marine type, but in certain cases the dry pump may be of the suction
valveless type.

The main features of this pump are the separate wet and dry air-pumps,
the separate suction for each pump, and the use of the injection water-cooler
for the dry pump. The dry pump discharges through the return pipe E^
through the spring-loaded v^ve F» into the wet pump barrel at a point below
the wet pump head valves. The supply of water to the dry pump for water
sealing, clearance filling, cooling of air, and condensing of any steam mixed
with the air, is obtained when starting by opening the filling valve G for a
minute or so to enable the vacuum to draw in a supply of water from the
diBcharge of the wet pump. The valve is then closed and the water x)asses

STEAM TURBINES.

from the discharge side of the dry pump by the pipe H to the ammlar cooler,
through which a supply of cold sea water circulates. After being cooled it
passes into the suction of the dry pump. Then, passing through the dry
pump, it becomes heated again, passes to the cooler, and so on in a continuous
closed circuit, any excess passing over through pipe E to the wet pmnp barrel.
The circulation through the cooler is provided for by the difference of pressure
between dry pump discharge and suction and by the removal of water from
the suction by the action of the dry air-pump.

FIGURE 49.

Blake Twinplex Pump.

The spring-loaded valve F is adjusted to maintain about 20 inches of
vacuum in the dry pump discharge when the condenser is working at about
28 inches of vacuum, and this 8 inches difference of pressure is sufficient to
cause the water to overcome the cooler friction and pass into the suction, and
at the same time never allows any direct air connection between the dry suction
and dry discharge.

The provision of separate pmnps for air and water suction results in a
high temperature of discharge from the wet pump and hence a high feed
water temperature. The air-cooler assists rapid air removal by the fact that
the water returning to the dry pump suction by way of the cooler cools the
air, reducing its temperature and volume.

MARINE TURBINE CONDENSING PLANTS.

Make Twinplex Pump (FIGURE 49). This system consists of wet and
dry air-pumps and a cooler. The wet pimip, which handles all the water,
takes its suction from the lowest point of the condenser through pipe A. The
dry pump removes the air and vapor, after they have passed through a part
of the cooling surface of the condenser set aside for air cooling, through
pipe C

A sufficient amoimt of water for sealing the pump valves in the dry pump,
clearance filling, and condensing of any steam mixed with the air, is taken
from a pocket in the discharge chamber of the wet piunp through pipe S; the
pocket being so located that the water will be as free from air as possible.
This sealing water, which is at a pressure corresponding to the wet pump
discharge pressure, is then forced through a tubular sealing water-cooler
into the dry air-piunp barrel between foot valves and bucket valves by means
of pipe R. The cooling water for the cooler is taken from the sea.

The wet pump discharges into the feed tank through pipe B. The dis-
charge pressure of the wet pump is therefore that due to atmospheric pressure
plus the head of water in the feed tank.

MQ VW\P.

FIGURE 49a.

Cooler Connection for the Dual and Twinplex Pinnps.

The dry pmnp discharges through a spring-loaded valve placed in pipe
D into the wet piunp barrel between bucket and head valves against a pressure
of about three pounds per square inch absolute. The bucket rod gland of the
dry piunp is sealed by means of water taken from the discharge of the wet
piunp to prevent air leakage.

The air-cooler built in with the condenser will lower the temperature
of the air and vapor about 15°F. below that of the water of condensation at
the bottom of the condenser.

The sealing water-cooler may be connected up for both this pump and
the Weir pump, as shown in FIGURE 48a.

Twin Air-Pumpt. This system consists of two vertical reciprocating
pumps. The air and water suction unite in one chamber, both pumps taking
water and air from the chamber. A feature sometimes installed is a pipe
from the top of this chamber to the discharge side of the air-pump buckets.
There is a non-return valve in this pipe. On the down stroke, the air-pumps
will then take air from this chamber into the space on the top side of the
bucket.

62 STEAM TURBINES.

LeBlanc Rotary Pump (FIGURE 50). This shows the general arrange-
ment of the vertical Mirrlees-LeBlanc system. The wet air-pump is situated
at the bottom with a suction from the bottom of the condenser. The dry
air-pump is at the top and has its suction attached to the condenser above
the level of the suction of the wet pump.

The wet pmnp is a centrifugal pump of special design. The dry air-
pmnp is operated by means of water. Its action is shown in FIGURE 51. The
pump impeller consists of a series of vanes situated at the periphery of the

wheel, the sealing water being admitted at the center. This sealing water
enters the rotating vanes from the stationary nozzle marked a and is then
discharged from the wheel at a high velocity and in thin sheets. These sheets
of water entrain the air and vapor drawn from the condenser and carry them
with it through the ejector at a high velocity, discharging with them against
the pressure of the atmosphere. The water sheets make an effective seal,
80 that it is possible for the highest vacuiun to be maintained behind them.
Referring to FIGURE 50, the dry air-pmnp discharges the mixture of
sealing water and air through the diffusers a to the top of the cooler. Here
the air separates and passes away, but the water passes through the cooler

MARINE TURBINE CONDENSING PLANTS. 63

and continues its eii'cuit to the pmnp. Any excess of cooling water due to
condensed vapor will overflow through an ovei-flow pipe to the feed tank. The
water in tlie cooler is cooled by means of circulating sea water.

FIGURE 61.

LeBIanc Pump.

An installation suuilar in principle to the above is built with a horizontal
shaft for the pumps used. In both cases, the pumps are driven by a small
steam turbine.

Assembled L. P. Ahead and Astern Parsons Turbine — Cummings.

CHAPTER VIII.
THE PARSONS TURBINE.

(Plates I, II, III, IV, and V.)
General Description. This turbine is of the compound reaction type. It
consists of a cylindrical casing with numerous rows of inwardly projecting
blades. Within the casing, which is of variable internal diameter, is a rotor
attached to a shaft. On this rotor are mounted rows of blades projecting
outwardly, by means of which the rotor and shaft are rotated. The shaft is
supported by suitable cylindrical bearings at both ends, outside of but attached

FIGURE 52.

Steam Flow Through
Reaction Blading.

to and forming a part of the casing. The blades attached to the casing are
called fixed or guide blades; those attached to the rotor are called revolving
or moving blades. The diameter of the rotor is less than the internal diameter
of the casing. Hence an annular space is left between the two. Tliis space is
occupied by the blades, and it is through these blades that the steam flows.

Steam from the boiler is admitted by suitable hand operated valves to the
admission or H. P. end of the casing directly to the first row of guide blades
fixed to the casing. After passing through these blades it strikes the first row
of rotor blades and changes its direction of flow. It discharges from the first
row of rotor blades into the second row of guide blades which reverse the
direction of flow. It discharges from the second row of guide blades against
the second row of rotor blades and continues through the turbine, as shown in
FIGURE 52, until finally it exhausts from the casing at a reduced pressure at
the exhaust or L. P. end of the turbine.

STEAM TURBINES.

The steam striking the rotor blades imparts a tm-niiig movement to tlie
rotor and to the shaft, and after reacting and passing through the series of
buckets of the H. P. turbine exhausts to the L. P. turbine. After expanding
through the L. P. turbine, the steam finally exliausts at a pressure of from
one to two pounds per square inch absolute into the condenser.

To keep the rotor in a fixed fore and aft position relative to the casing,
an adjusting block is used. It is outside the casing, and is secured to and
foniis a part of the casing. It is sometimes constmcted for the additional
purpose of taking up steam or propeller thrust.

FORWARD

AFT

FIGURE 53.

Wing Blading.

Where the shaft passes through the casing at both ends, shaft glands with
labyrinth packing are provided to prevent steam leakage from the casing
when the pressure inside the casing is greater than atmospheric pressure ; and
to prevent air leakage to the casing thence to the condenser, if the pressure
inside the casing is less than atmospheric pressure.

To prevent steam leakage from the admission steam chest to the space
at the ends of the rotor or inside the rotor, packing is fitted on a cylinder that
is attached to the casing, and is fitted on the dummy piston attached to the
rotor. This packing is called the dummy packing.

Esqpaiuions. As the steam passes through the buckets, the pressure
gradually falls and the volume increases. Theoretically, the expansion is
adiabatic, and the blade heights should gradually increase from the H. P. end
to the L. P. end of the turbine. In practice, however, this is not carried out.
As the increase in volume is not rapid in the H. P. turbine, the blades are
arranged in sets of equal height, each set being called an expansion. The

THE PARSONS TURBINE.

clearance space, or the bucket volume between the blades, increases in propor-
tion to the increase in blade height. The increase in height from one expan- *
sion to the next is not very great. When the L. P. turbine is reached, in
addition to increasing the blade height, the diameter of the blade annulus is
increased to take care of the increased volume of steam. In the L. P. end of
the L. P. turbine, to continue increasing blade heights would give an excessive
height to blades ; and to continue increasing blade annulus diameter would give
a prohibitive diameter to the casing. The blades of the last three expansions
of the L. P. turbine are, therefore, of the same height, and increased bucket

9'jtm.fn

FIGURE 109.

Ai'izona.

volmne is obtained by setting the blades of each successive expansion at a
smaller angle to the axis of the turbine. These blades are called '' wing
blades." Thev are shown in FIGURE 53.

ARIZONA'S Turbines. The tur])incs of the ARIZONA are representative
of the construction of the Parsons type as installed in large units. The ship
has four propeller shafts. The port installation is the same as the starboard.
On the outboard shaft is a direct connected T^. P. ahead and astern turbine
contained in one casing. Geared to this shaft is a cruising turl)ine. On the
inboard shaft is a direct ccmnected H. P. turbine; and aft of it on the same
shaft is a H. P. astern turbine. These turbines are in separate casings (see
FIGURE 109).

STEAM TURBINES.

w Murine StffDm Turbinj Cn.

Starboard Turbines (Viewed from jVhead) with Reduetion Gear — Wadsworth.
H. P. Turbine. Reduction Gear. L. P. Ahead and Astern Turbine.

FIGURE 113.

Wadswurtli.

THE PARSONS TURBINE. 69

WADSWORTH'S Turbinn. The turbines of the WADSWORTH are rep-
resentative of the construction of the Parsons type as installed in small units.
There are two propeUer shafts. The starboard and port installations are the
same. Each propeller shaft has a large gear-wheel attached to it at its forward
end. To this gear-wheel is geared a pinion on the H. P. turbine shaft, and a
pinion on the L. P. and astern turbine shaft. The H. P. turbine is outboard,
and the L. P. turbine is inboard (see FIGURE 113).

Paiit I.
H. P. TURBINES.

Plate I.— H. P. ahead turbine of the ARIZONA.
Plate II.— H. P. ahead turbine of the WADSWORTH.

Rotor. The rotor of the H. P. turbine of the ARIZONA is of the built-up
type. The parts consist of the drmn attached to a wheel forward and a wheel
aft. The wheels are attached to the shaft forward and to the shaft aft. The

Caulked

FIGURE 64.

Wheel, and Shaft Connection, L. P. End of
H. P. Turbine — Arizona.

70 STEAM TUKBINES.

drum is strt'iigthened in the middle by a strengthening ring attached to the
drum on the inside. Attached to the wheel at the H. P. end is the dnnmiy
piston. The drums are worked out of solid ingot, and are rolled to shape in
large rolls. The drmn is then rough turned and bored to fit the wheels, l^he
wheels are shrunk on to the shafts and secured b}' set screws with ends riveted
and caulked to prevent tm-ning loose. The drum is then shrunk on the wheols
and secured b\' sei-ews to the rims of the wheels. FIGURE 54 shows the
method of securing drum, wheel, and shaft at the Ij. P. end of the turbine.

In large turbines the spokes of the wheel at the H. P. end are usually
hollow. These hollow spaces are connected to the entrance steam chest and

FIGURE 66.

Rotor and Wheel Connection, H. P. End of
H. P. Turbine— Wadsworth.

to a hollow space in the shaft. This allows steam to flow inside the wheel
spokes and inside the shaft for the purpose of obtaining uniform heating
when wanning up the turbine preliminary to starting.

The rotor of the H. P. turbine of the WADSWORTH is of the built-up
type, but owing to the smaller size of turbine it consists of only the drmn and
two wheels. Each wheel is forged integral with the shaft. The drum is
extended in length at the H. P. end to fomi the dummv piston. The method
of securing the drum to the wheels is shown in FIGURE 55 which represents
the H. P. end of the rotor.

THE PAESONS TURBINE. 71

Dnnui^ Piston and Packing. On the dmmny piston, collars are turned
to form a part of the dummy paddng. Surroimding the dummy piston is
the dummy cylinder. In grooves cut for the purpose are secured composition
rings to the dimimy cylinder to form the other part of the dummy packing.

H. P. dummy packing is of the axial clearance type, as shown in
FIGURE 56 (see p. 74, folder). Steam leakage is almost wholly prevented
from the H. P. steam chest to the inside of the rotor by making the clearance
between the edges of the packing rings and the collars on the dummy piston
very small. The clearance in practice is from .015 to .030 of an inch. Steam
that leaks through the clearance spaces is alternately wire drawn and expanded.
In the ARIZONA'S H. P. turbine such leakage as takes place flows to the
exhaust from the turbine via the inside of the drum. In the WADSWORTH'S
H. P. turbine there is a space in the dummy cylinder from which a pipe is led
to a L. P. expansion. At the end of the casing another pipe is connected and

Dummy Packing RinKs

FIGURE 67.

Dmnmy Packing Rings Cut for Drainage.

led to the auxiliary exhaust. These spaces are called the dummy leak-offs,
and are used to admit steam when warming up the turbines.

At the bottom of the dummy cylinder, grooves are cut from tiie dummy
strips flush with the internal surface of the cylinder, as shown at d in
FIGURE 57. This is done to provide drainage to the bottom of the casing
for water formed by steam condensation within the dummy packing.

Casingi. The casings are made of cast iron. The casing is divided into
two parts with a joint along a horizontal plane through the center line of the
turbine. Each paj^; is flanged at this joint. In large turbines each half of the
casing sometimes consists of three to four pieces bolted together at circum-
ferential flanged joints. This is done to insure sound castings.

The casing of the ARIZONA'S H, P. turbine is in two halves, top and
bottom. The dummy cylinder at the H. P. end is a separate casting bolted
to the casing. The bottom half of the bearing casings at each end are bolted
to the lower half of the turbine casing. The bottom half of the turbine casing
is secured by bolts to the framing of the ship, which forms the turbine
bed-plate.

THE PARSONS TURBINE.

The castings forming the casing are strengthened by longitudinal and
circumferential ribs on the outside of the casing.

The casing is heavily lagged with heat insulation material to prevent
heat radiation from the turbine.

The H. P. turbine casing of the WADSWORTH is in tw^o parts, top and
bottom halves, secured together by a bolted flanged joint.

Shaft Glands. Shaft glands are provided at the ends of the casing where
the shafts pass through the casing. A typical shaft gland is. shown in
FIGURE S8, with a detailed view of the packing in FIGURE S9 (see p. 74,
folder). The gland consists of gland body C in halves, gland sleeve A in
halves, ring case B in three parts, and vapor hood D in halves.

Joint

FIGURE 60.

Shaft Gland Snap Ring.

The gland body C holds the parts of the gland and is secured to the casing
by means of a flange and bolts. The gland sleeve A has grooves cut on the
inside surface into which the labyrinth packing rings are secured, as shown
in FIGURE 59. Packing rings are also secured to grooves in the shaft and
extend outwardly between the sleeve gland rings. The clearance in this case
is radial. The ring case B holds the snap rings which expand against the
inner surface of B. These snap rings are held between collars turned on
the shaft. The vapor hood D collects the steam that leaks through the
-gland and discharges it through a pipe to the drainage system. The snap
rings are in two pai*ts, as shown in FIGURE 60. Between the packing rings
and the snap rings is a space from which steam leakage may be taken to a

74 STEAM TURBINES.

L. P. expansion or to the drainage system. Steam may be admitted to this
space when warming up. Groove R is for the purpose of inserting a tempo-
rary ring when the lower part of the gland sleeve is revolved and removed,
to prevent fouling of the packing rings. The action of the labyrinth packing
rings is the same as that of the dummy packing. The edges of the packing
rings are made sharp to prevent any heating or damage if the rings touch the
shaft or the sleeve. The leak-off pipes may be used for the admission of steam
when wanning up or to seal the gland against air leakage from outside the
casing. The glands are fitted with drain-pipes at the bottom to carry away
water formed from steam condensation within the gland.

Adjuttmg and Thrust Blocks. As the propeller thrust is usually balanced
by pressure of the steam acting in the opposite direction to propeller thrust,
thrust blocks are not called upon to receive the propeller thrust as usually
understood in connection with ordinary marine practice. The block is chiefly
required to take the thrust when the steam is turned on or off and to retain
the rotor in a proper position fore and aft. The position of the thrust blocks
is determined by the clearance required in the dmnmy packing.

The type of adjusting block used for both H. P. and L. P. Parsons turbines
is shown in FIGURE 61 (see folder). These blocks are usually at the forward
end of the turbine and just forward of the forward main bearing. The
bearing body consists of a top and a bottom half. The bottom half is secured
to the casing and bed-plate. The upper half is adjustable fore and aft. In
the lower half is the ahead thrust bushing to which are secured the ahead
thrust rings. In the upper half is the astern thrust bushing to which
are secured the astern thrust rings. The thrust rings are made of com-
position and are set in grooves machined in the thrust bushings, the steel
edges of each groove being caulked into serrations cut in the ring. The bottom
thrust bushing is adjusted fore and aft by altering the width of distance rings.
The top thrust bushing is adjusted by moving the bearing cap by means of
adjusting bolts and nuts, as shown in FIGURE 62 (see folder). Additional
adjustment fore and aft may be obtained by varying the width of the astern
distance rings.

After the rotor is placed for the desired dummy clearance, the astern
and ahead thrust bushings are adjusted to leave from .004 to .015 of an inch
clearance between thrust collars and thrust rings to allow for lubrication, as
the thickness of the oil film is appreciable.

As the turbine is designed so that the steam thrust practically balances
propeller thrust, the wear due to thrust on the thrust rings is practically nil.

The turbine of the WADSWORTH is provided at the forward end with
an adjusting block of similar design. The main bearings and adjusting block
are omitted in PLATE II. The thrust of the propeller is, however, on the
shaft to which is secured the main gear-wheel of the reduction gear. A
thrust block is therefore provided forward of the reduction gear box. It may
be of the usual marine type. In the case of the WADSWORTH, a Kingsbury
thrust is provided. This type of thrust is coming into general use, and is
shown in FIGURE 63 (see folder). The shaft has but one thrust collar, the
forward side of which takes up the ahead thrust and the after side the astern
thrust. The thrust blocks are in segments, each mounted on a spherical bearing.
This is for the purpose of providing proper lubrication. When a thrust block

Under

Enlarged View of
mmy Packing Strips

lummy Piston

FIGURE 66.

H. P. Dummy Packing (Axial

ung

onap niii£»

Enlareed View of

Labyrinth Packing

Rings

■ 3

! 1

(""

FIGURE 62.

Method of Adjusting Thrust
Bearing Cap.

Securing Nut

THE PARSONS TURBINE. 75

is under load with an abundant supply of oil, the oil is carried in between the
thnist collar and the thrust block. As the oil flows from the sides and end
of the hlock (the oil film is thicker at the entrance than at the exit end)
the lilock will cant slightly and adjust itself readily to the position demanded
by the load, and allow the oil to take a wedge shape and totall}- separate the
collar and block. This provides practically perfect lubrication. Shop tests of
this bearing have been made, wliich demonstrate that the thrust blocks will
work satisfactorily under loads as high as o910 pounds per square inch with a
surface speed of 3240 feet per minute.

Cruising Elxpansions. The Parsons H. P. turbines of late design are
fitted at the H. P. end with additional expansions called cniising expan-
sions. The ARIZONA'S H. P. turbine has two cruising expansions. The
WADSWORTH'S H. P. turbine has four cruising expansions. The purpose
of these expansions is to obtain lower propeller speeds for low cruising speeds
of the ship with economical perfonnance of turbines. When higher powers
are demanded, steam is admitted to an expansion further along in the H. P.
turbine, the cruising expansions being I>y-passed and not used. These high-
power steam admissions are shown on PLATES I and II, and in the ease of the
ARIZONA and WADSWORTH are used for full power.

Part II.

L. P. TURBINES.

Plate III.— L. P. ahead and astern turbine of the ARIZONA.

Plate IV.— L. P. ahead and astern turbine of the WADSWORTH.

Rotor. The L. P. ahead and astern rotor of the ARIZONA'S L. P.

turbine is of the built-up type, consisting of the ahead drum, the astern drum,

Rotor of Parsons L. P. Ahead and Astern Turbine — Cunmiings.

the junction wheel, and a wheel at each end attached to the shaft. The dununy
pistons are made of separate forgings and are attached to the wheels. There
is a dunnny piston at the admission or H. P. end of the ahead turbine, and
one at the admission end of the astern turbine. Both ahead and astern rotors
form one and are in the same casing. The astern blading is under the exhaust
to the condenser, this space in length thus being utilized in this turbine.

STEAM TURBINES.

Caulked

FIGURE 64.

Rotor, "Wheel, and Shaft Connection, L. P.
H. P. Turhine — Arizona.

THE PAESONS TURBINE. 77

The method of connecting wheel, shaft, and dmniny piston of the
ARIZONA'S turbine is shown in FIGURE 64. The wheel is shrunk on the
shaft and secured by screws. The drum is shrunk on the wheel and secured,
as shown in FIGURES 54 and 55. The ahead drum and the astern drum are
connected by a cast steel junction wheel, as shown in FIGURE 65. The junc-
tion wheel has holes cut around its circumference to allow steam to escape
from the inside of the drum to the exhaust.

FIGURE 66.

Rotor and Wheel Connection, H. P. End of
H. P. Turbine— Wadsworth.

The dummy piston is made of smaller diameter than the drum to provide
for balancing the propeller thrust by the action of the steam in the admission
steam chest against the annular space thus provided (see FIGURE 64). This
is true of both the ahead and the astern dummy piston.

The wheels at each end have hoUow spokes, connected with the admission
steam chests, extending to hollow spaces in the ^fts. These passages provide
- for steam entrance when warming up the turbines.

f 78 STEAM TURBINES.

FIGURE 66.

Junction Wheel Connecting L. P. Ahead and Astern Drums — Arizona.

wtmnMP Ad._

THE PARSONS TURBINE. 79

The L. P. ahead and astern rotor of the WADSWORTH'S L. P. turbine
is biiilt up as shown in PLATE IV. The ahead drum and the astern drum are
formed from one forging. The wheels at either end are foiled integral with
the shaft. The drum is secured to the wheels, as shown in FIGURE 66. The
dummy pistons are forged and machined as a part of the wheels. Where
the wheels are solid in a turbine, as in tiiis case and in the case of the
WADSWORTH*S H. P. turbine, there is a steam leak-off from the space

Rii.ataH .

FIGURE 66.

Drum and Rotor. H. P. End of L. P. Turbine— Wadsworth.

between the casing and the end of the drum. The steam that leaks through
the dummy packing from the admission steam chest is then carried to an
expansion containing steam at a lower pressure. The leakage from the
WADSWORTH'S astern steam admission chest is led to the exhaust pipe
through openings in the astern dummy cylinder.

Dummy Futon and Paddng. Referring to FIGURE 64, it will be seen
that steam leakage from the admission steam chest to the inside of the rotor
is prevented by dummy packing secured to the dmnmy piston and cylinder.

80 STEAM TURBINES.

This packing la shown in detail in FIGURE 67. It is of the radial clearance
type with very smaU clearance between the edges of the packing rings and the
piston and cylinder. Its action is the same as that of the dummy packing
already described.

Cylinder

Enlarged View of
mmy Packing Rings

)unimy Piston

FIGURE 67.

L. P. Dummy Packing (Radial Clearance) — ^Arizona.

Casing. L. P. casings may be built of from six to eight pieces, depending
on the size of the turbine, to insure making sound castings. The L. P, turbine
casing is divided into halves by a horizontal plane through the center line of
the turbine. The joint is flanged and bolted. This construction allows of the
top half of the casing being lifted for an examination of the inside of the
turbine. Large steam and exhaust ports are braced, as shown in PLATES
— 1 IV.

THE PARSONS TURBINE. 81

The astern casing is under the exhaust opening of the turbine and is a
separate casting. It is secured to the ahead casing by a bolted flange and joint.
The forward end is supported by feet secured to the astern casing and resting
on the inside of the ahead casing. These feet are free to move in a fore

L. P. Ahead and Astern Turbine Casing — Parsons Tm-bine — Cuinmings.

and aft direction on the inside surface of the ahead casing, to allow free
expansion of the astern casing when the turbine is heated.

In large turbines, such as the ARIZONA'S, the duirmiy cylinders are
separate castings secured to the casing by bolted flanged joints. In the
WADSWORTH'S L. P. turbine, the dummy cylinders ai'e a (lart of the same
casting as foi*ms the ahead turbine.

L. P. Ahead and Astern Turbine Casing With Cover Removed —
Parsons Turbine — Cummings.

Shaft Glands and Adjiuting Blocks. Shaft glands and adjusting blocks
are of the same general design as for the H. P. turbine.

Tlie main bearings and adjusting blocks of the WADSWORTH'S L. P.
and astern turbine are not shown on PLATE IV.

82 STEAM TURBINES.

Part III.

GEARED CRUISING TURBINES.

Plate v.— Cruising turbine of the ARIZONA.

The latest practice in the installations of war-ship turbines is tending
toward the use of a geared cruising turbine on each one of two shafts on
battleships, and on one shaft on torpedo-boat destroyed. This is a small
tiu-bine, as shown on PLATE V. It runs at a high speed, giving econuinie^I
results for the tiu'bine pei'forniance. Through the i-eduction gear, it allows

FIGURE 68.

L. P. End of Cniising Turbine — Arizona.

the propeller to run at low speeds demanded by low cruising speeds of the
ship. This turbine with its reduction gear is disconnected for high speeds
by means of a clutch. It is of the same general type as the H. P. turbine
of destroyers. FIGURE 68 shows the method of securing the drum to the
combined wheel atid shaft.

The cruising turbine has five expansions. At speeds al)ove 12 knots, the
first expansion is not used. At speeds above \'i knots, the fii-st, second, and
third expansions are not used. At speeds above 17 knots, the cruising turbine

THE PARSONS TURBINE.

with its reduction gear is disconnected from the propeller shaft by means
of the clutch.

The shaft gland at the H. P. end of the turbine has two leak-oflfs, from
which steam leakage is led to a lower pressured expansion. The shaft gland
at the L. P. end of the turbine has two leak-offs, from which steam leakage
is led to a lower pressured expansion.

The estunated pressures for the expansions of the ARIZONA'S turbines
for different speeds are given in TABLE A. The figures represent the pres-
sures at the beginning of each expansion indicated for ahead and astern power.

TABLE A.

COMBINATIONS USED FOR VARIOUS SPEEDS AND ESTIMATED PRESSURES IN

POUNDS ABSOLUTE.

Speed in knots

21
34,000

19
20,450

Cruising
turbine.

1st expansion .

By-pass

2d expansion .
3d expansion .

By-pass

4th expansion.
5th expansion.

17
13,700

PonndK.

Cruising turbine
disconnected.

11. P. ahead
turbine.

I 1st expansion.
2d expansion .

Pounds.

170
112

Pounds.

116
76

142
03

65
43

8,050

Povnds.

215

148

93
61

45
30

12
4,640

Pounds.
195

• • • •

116
80

54
35.5

10
2,830

Pounds.
132

• • • •

75
52

■ • • •

21.7

15.75
10.5

Auxiliary exhau>t connection to 3d expansion.

3d expansion . .
4th expansion. .
5th expansion. .
6th expansion. .

/ 1
51
35
21

53
35
24
14

29.5
19.5
13.5
8

20.5
13.5

10.5
6.75
4.75
2.75

7.25
4.75

L. P. aliead
turbine.

Auxiliary exhaust connection to Ist expansion.

1st expansion,
2d expansion .
3d expansion ..
4th expansion.
5th expansion.
6th expansion,

15.5
10.75

7.5

3 . 25

2.25

10.5
7.3
5

3.5
2.25

4.25

2.25

* • • ■

1.5

Exhaust

pressure

.i .

1 lb.
28" vac.

.75 lb.
28.5" vac.

.50 lb.
vac.

29"

.50 lb.
vac.

29"

.50 lb.
29" vac.

ASTERN TURBINES. ESTIMATED PRESSURES IN POUNDS ABSOLUTE.

Full speed astern.

^ H. P. astern turbine steam belt. ..
-! j L. P. astern turbine steam belt. ..
[ Vacuum

.135 lbs.
. 21 lbs.
. 27 inches.

Part IV.
GENERAL DETAILS.

Blading. The blading for the Parsons turbine is of composition manu-
factured in sha])es of A'arious standard cross-sections in lengths of from five
to six feet. The bhides are cut to the proper lengths in a machine which shears
them off and at the same time stamps a double or treble groove at one end.

Since the blades are of various lengths for the different expansions, the
rotor is left parallel and the casing is stepped to different diameters to suit.

84 STEAM TURBINES.

For blades of 5^ inches and less in length, a groove is cut on the entrance edge
at the end opposite to the eanlking grooves, into which is secured the binding
strip. The blades are then thinned at the tips, as shown in FIGURE 70, by
a special machine. This is done to prevent damage in ease the blade tips
touch when the turbine is in operation. If the blade tips touch the rotor or
casing while the turbine is in operation, the thiniied ends of the blades will
be bent over and stripi)ing of the blades will be prevented.

The blades are secured in grooves machined in the casing and in the rotor
with small caulking grooves, as shown in FIGURE 69. To give the blades the
proper distance apart in the cji-cumferential dire<'tion and to give the blades

Casing

uiauc uiwvca

FIGURE 69.

Blade Grooves.

the designed exit angle, small packing pieces of annealed brass are fitted
between each ])air of blades. When the blades are put in place these packing
pieces are caulked to fill the caulking grooves in the rotor or casing,
FIGURE 69, and to fill the caulking gi-ooves at the root of the blades, as shown
in FIGURE 70.

The usual practice is to assemble and secure the blading by what is known
as the Parsons " segment system." The blades and packing pieces are strung
on a small brass wire run through holes in the i-oot of the blading, as shown
in FIGURE 71. The segment of blading is assembled in a fonner consisting
of two cast-iron plates which arc bolted together, and have a groove turned
in them equivalent in size and radius to the groove in the rotor or in the easing.
A packing piece is taken, and. through a hole drilled through it, a piece of

THE PAESONS TURBINE.

brass wire of required length is passed. The end of the wire is riveted. The
packing piece is then secured in the groove of the former, and blades and
packing pieces are alternately strung on the wire. The blades and packing
pieces are driven close together and care taken to have them resting on the
bottom of the groove. A segment starts with a packing piece and ends with a
blade. The blades are now trued up and spaced. After this, the binding strips

Lacing

Tips
Thinned

Binding
Strip
(laced)

Outer

Binding

Strip.

(iaced)

Inner

Binding-^
Strip P"
(not Laced) I

ades 5Vt in.
or Less in

Blades Over
5V4 in. In

Height

FIGURE 70.

Parsons Blading.

are fitted into the grooves at the top of the hladea. The outer binding strips
are laced with copper wire, as shown in FIGURE 70. The wire and binding
strips are now soldered with silver solder. The inner binding strip, which
is fitted only to blades over 5} inches in length, is not laced but is secured by
brazing. After the segment is completed, the brass stringing wire is cut and
riveted over the hole in the last blade. The segments are removed to the
turbine and placed and seciu'ed in their proper grooves.

86 STEAM TURBINES.

When a groove of the rotor or easing is filled with ita proper number of
segments, two or three packing pieces in each segment are slightly caulked
BO as to prevent the segments from rising or falling out. The packing pieces
are now caulked sufficiently to insure securing the blades in place. Alternate
segments are first caulked. If the caulking is carried right aroimd, the last
segment to be caulked will rise out of its place.

After the rotor is completely bladed, it is placed in a lathe and the blade
rows are straightened so that all the blades of each row are square with the
rotor and revolve in the same plane. A very light cut is taken from the blade
tips to bring the blade rows to the proper diameter. This operation is impor-
tant as the tip clearance depends upon it.

pOTOR BLADES

rrn rm rm n~n rm rm

i:, J!,„ M i; ij !! ;:

LUJ '

FIGURE 71.

Segment Former for Parsons Blading.

The blading of the casing is secured in the same mamier, having regard
for the fact that roots of blades fasten in a groove in the former that is concave
instead of convex as for the rotor.

Main Bearings. A hearing is placed at each end of the turbine to guide
and support the rotor. It is of the usual marine type designed for forced
lubrication. The bearings are in halves, made of composition lined with white
metal. The lower half may be removed by lifting and removing the bearing
cap and top bearing and revolving the lower bearing around the shaft.

Steam Connectitnu. The usual steam connections to the rotor casing
may be tabulated as follows:

1. Steam inlet at the forward end. In the H. P. turbine this is direct
from the boilers. In the L. P. turbine, it is frmn the H. P. turbine
exhaust.

2. Steam inlet at forward end of the H. P. turbine. This is from
the exhaust of the geared cruising turbine.

THE PARSONS TURBINE. 87

3. Exhaust at the after end. In the geared cruising turbine this
leads to the forward end of the H. P. turbine. In the H. P. turbine it
leads to the inlet at the forward end of the L. P. turbine. In the L. P.
turbine it leads from the turbine to the main condenser and is of consider-
able size to accommodate the large volume of the exhaust steam at very
low-pressure.

4. Steam inlet at forward end of L. P. turbine of certain destroyer
installations. This supplies H. P. steam direct to the ahead L. P. turbine
when maneuvering.

5. By-pass pipe on H. P. turbine from cruising steam inlet to full
power steam inlet. This by-passes steam aroimd the cruising expansions
for full power, when warming up, or when starting to prevent blade
damage by excessive vibration in the H. P. turbine.

6. Relief valves are fitted on steam chests to relieve excessive steam
pressures.

7. Gland steam connections. Steam connections to leak-offs of shaft
glands for warming up, and, for the L. P. turbine, to form a steam seal
against air leakage into the turbine.

8. Dummy leak-off connection. This carries steam from the dmnmy
leak-off of ahead turbines to the third and fourth expansions.

9. Connections for pressure gages. A connection may be made at
the beginning of each expansion for a pressure gage.

Drains. The drains from turbine casings to remove water when warming
up, when stopped temporarily, and when running, are fitted as follows :

1. Drain from diunmy cylinder to after end of titrbine casing. This
allows any water to drain from the higher forward positions of the
casing to the after lower positions. These drains are used only when
warming up or when stopped temporarily.

2. Prom L. P. casing to wet air-pump suction. These drains from
the after end of the L. P. casing are fitted with a light non-return valve,
and a U-bend to act as a water seal. This carries away water from the
L. P. turbine casing while running and when warming up.

3. From the H. P. casing to the L. P. drain-pipe. These drains from
the after end of the H. P. casing to the L. P. drain-pipe are fitted to drain
water from the H. P. casing when running and when warming up. If
the exhaust pipe from the H. P. to the L. P. turbine is low down, water
will easily flow through it to the L. P. drains.

All casing drains can be opened to the bilge when required. The valves
on drains from the H. P. exhaust pipe to the L. P. casing are just cracked
when nmning so that they will be water sealed, or are shut altogether.

Balancing Rotors. Two balances are required to insure a steady nmning
rotor. These are the static balance and the dynamic balance.

The static balance is obtained by revolving the rotor on a pair of knife
edges or balancing stools which consist of two supports of cast iron having
on top a truly machined face of hard-grained cast iron. The stools are levelled
up longitudinally and levelled to each other, after which the rotor is laid on
them. The bearing parts of the shaft, or the journals, rest on the stools. The
rotor is revolved and allowed to come to rest. The point at the bottom will be

88 STEAM TUEBINES.

the heaviest. Weights are added and the experiments continued until the
rotor wiU stand at rest in any position.

The rotor is balanced dynamically by one of two methods: (1) by being
revolved by steam acting as imder working conditions, and tested for vibration
by fixed indicating pointers or pencils; (2) by some arrangement in which the
rotor is rotated by some external power through the rotor shaft. As before,
a pointer indicates the vibrations on a piece of diagram paper bv a more or
less waving line.

The latter method is the more accm^ate, as the rotating force acts from the
center outwards and tends to magnify any lack of balance or difference in
weight which the rotor may possess. At the same time, few rotors are actually
in a state of perfect balance, as no really scientific and accurate method of
dynamic balance has been devised for turbines.

The rotor should be revolved to at least 20 per cent above the designed
revolutions. Should the balance be imperfect, it will show by vibrations being
set up, and if the balance is very bad, it may result in damaging the blading.
When the rotor is at its worst point of vibration, marks should be put on the
shaft simultaneously at the after and forward ends. The relation of the
marks to each other is noted by stopping the turbine. Weights are then
shifted longitudinally as determined by experience. The static balance is
maintained but the dynamic balance is improved by continued tests followed
hy shifting weights longitudinaUy.

The various parts which go to make up the complete rotor, such as drum,
wheels, shafts, junction wheels, are each carefuUy balanced before assembling,
then the whole is again balanced on knife edges, after which an approximate
dynamic balance test is run.

Weights may be added to or cut away from the rotor to obtain the proper
balance. In the latter case, eight balance stubs are fitted to the wheels and
cut off as required to lighten the heavy side of the rotor, in place of adding
weights to the lighter side.

PLATE n.

Parsons' H. P. Turbine — ^Wadsworth.

Expa

^Mta^^M

•r

14'

r ShlpbullJlDK Corp.

Curtis Main Turbine — Tucker.

CHAPTER IX.
THE CURTIS TURBINE.

(Plates VI, VII, VIII, and IX.)

General Detcriptioti. This turbine is of the impulse type and embraces
the principles of pressure staging and velocity compounding. The H. P.
stages are usually velocity compounded; that is, the velocity acquired by the

ReUtiv«

Pr«ssur«S ^■_ „ I ^

Pressure <t^« Pms^CTagc fV«4j^«r«g« 4ti.P

FIGURE 72.

Steam Flow Through Impulse Nozzles and Blades.

steam in the nozzles in each pressure stage is absorbed by several rows of
moving blades. The L. P. stages are simple pressure stages; that is, each
stage consists of a row of nozzles and one row of moving blades.

The action of the steam in the five pressure stages of an impulse turbine
is shown in FIGURE 72. The first, second, and third pressure stages are each
vdocity compounded twice, the succeeding two pressure stages are simple
pressure stages.

The steam is expanded in the nozzles of each pressure stage with increasing
velocity and is discharged against the moving blades which change its direction
of flow. It is then gxiided through stationary blades to its original direction
and from them is discharged against the second row of moving blades. The
process continues throughout each velocity compounded pressure stage. The

90 STEAM TURBINES.

steam gains velocity in the nozzles, loses velocity in the moving blades, and
has constant velocity in the guide blades. To insure constant velocity in the
buckets of the guide blades, or to make up the loss of velocity due to frictional
resistance, the height of the blades in a velocity compounded pressure stage
is gradually increased.

In the simple pressure stage, the steam expands in the nozzles acquiring
velocity due to this expansion. It then discharges against the single row of
moving blades. From them, the steam discharges into the space between the
moving blades and the next row of nozzles.

The pressure at all points in any one pressure stage after the steam leaves
the nozzles is practically equal. To insure equality of pressure, holes are cut
in the wheels.

The impulse turbine is made up of a rotor consisting of a shaft to which
are attached wheels for each pressure stage that is velocity compounded. The
moving blades which, through the impulse of the steam upon them, impart
motion to the rotor are secured to the rim of the wheels and project outwardly.
The moving blades of the L. P. stages are secured to drmns and project out-
wardly. The nozzles of the pressure stages that are velocity compounded are
secured to diaphragms which are stationary. The guide blades of the velocity
compoimded pressure stages and the nozzles of the L. P. stages are secured to
the inside of the casing and project inwardly between the rows of moving
blades. The buckets of the guide blades, which are in the wake of drum
blading, form the nozzles of the several simple pressure stages found at the
L. P. end of the turbine. There is a space between the rim of the rotor wheels
or rotor drum and the inside of the casing. This space is occupied by the
blading. It is through this blading and the stationary nozzles that the steam
flows.

Curtis turbines built in large units are usually in two separate casings
and form what are called the H. P. turbine and the L. P. ahead and astern
turbine. Small units are contained in one casing with combined ahead and
astern turbines in the same casing.

The shaft is supported by bearings outside of and forming a part of the
casing. There is a bearing at each end of each turbine. In order to keep
the rotor in a fixed fore and aft position relative to the casing, an adjusting
block is used. It is outside the casing and is secured to and forms a part of
the casing. The usual position for the adjusting block is forward of the
forward main bearing. As propeller thrust is more than coimterbalanced by
steam thrust on the L. P. drum of the turbine, the adjusting block takes a
very small amoimt of thrust and is, therefore, of small size and capacity.

To prevent steam leakage from the first pressure stage where the shaft
passes through the casing, a shaft gland packed with carbon rings is secured.
At the L. P. end of the turbine, the shaft gland prevents air leakage into the
last pressure stage and thence to the condenser.

As the pressure is lower in each succeeding stage from the H. P. end of
the turbine, a bushing with packing is provided on the inner rim of each
diaphragm where the shaft passes through the diaphragm to prevent steam

THE CURTIS TURBINE.

leakage from one pressure stage to the next succeeding pressure stage. Dia-
phragms are provided to separate one pressure stage from the next adjacent
pressure stage where drum construction is not used.

The nozzles of all velocity compounded pressure stages but the last do
not cover the full circimiference of the diaphragm. This is done in order
that the blade heights of the first few pressure stages will not be too small.
From and including the last velocity compoimded pressure stage, the admission
of steam to each stage is around the whole periphery. To accommodate the
increasing volume of steam as the steam flows to the exhaust, the blade heights
are increased and nozzle cross-sectional areas are increased. Speed control
is effected by the closing and opening of nozzles by suitable hand controlled
valves in the first pressure stage.

Aft

C^ntcfr line

Brcpelleic

tvirblv d

"SKaTT

Twd

FIGURE 119.

Cushing.

TUCKER'S Turbines. The turbines of the TUCKER are representative of
the Curtis turbine as built in small units for marine propulsion. There are
two propeller shafts. The starboard and port installations are the same.
Direct connected to the propeller shaft is the main ahead and astern turbine.
The ahead and astern turbines are in the same casing. Connected to the
propeller shaft forward of the main turbine is a cruising turbine. The con-
nection between the cruising turbine and the propeller shaft is made through a
reduction gear and a clutch. The TUCKER'S cruising turbine is representa-
tive of the type (see FIGURE 119).

NEVADA'S Turbines. The turbines of the NEVADA are representative of
the Curtis turbine as built in large units for marine propulsion. The installa-
tion in general arrangement is the same as for the TUCKER. Instead of one
main turbine, however, the main turbine is made up of two units, both direct
connected to the shaft. The H. P. ahead turbine is in the forward engine-
room and the L. P. ahead and astern turbine, which are both in the same

92 STEAM TURBINES.

casing, is in the after engine-room. A cruising turbine is connected to each
shaft at its forward end through a double reduction gear and a clutch (see
FIGURE 110).

FIGURE 110.

Nevada.

Pake I.

CBUISING TURBINE.

Plate VI.— Cruising turbine of the TUCKER.

Rotor. This turbine is pressure staged five times. The first three pres-
sure stages are each velocity compounded twice. The last two pressure stages
each have one row of moving blades. The rotor consists of a shaft turned
to receive the velocity wheels from each end. The greatest diameter of the
shaft is under the second diaphragm. The wheels are shrunk on the shaft
and secured by keys. To provide proper spacing of wheels in the axial direc-
tion, steel distance rings are accurately machined and shrunk on the shaft
between the hubs of the wheels. The wheels and distance rings are finally
secured at either end by nuts set up against the last shoulder on the shaft and

THE CTRTIS TURHIXE.

Cui-tis <'i-nisiiin Turbine with Kodiu-tion (.ioar^ — ^Tiu-kcr.

Ki>Tu lllviT shlM>iill<]liii- r„rii.

Kdtoi- of Ci-uisiii;; Turl)iiU' — Tiirkcr.

94 STEAM TURBINES.

against the hub of the last wheel on the shaft. The nuts are secured from
turning by set screws. The wheels are made of forged steel, each wheel in
one piece, as shown in FIGURE 73. The rim of tlie wheel is gi-ooved to I'eeeive
the moving blades. The blades ai'e uniformly continuous around the wheel

Fare River StilpliiilKllDg Torp.

Rotor in Place in Lower Half of Cruising Turbine
Casing — Tucker.

'■an nivpr ShIi'biillillDR rnrii,

Lowe]' Half of Cruising Turbine Casing — Tucker.

rim. Holes are usually drilled in the wheel disc to insure equality of pressure
on both sides of the wheel.

Bearings and Adjusting Block. The shaft is snppoi-ted at either end by
bearings outside of but secured to and forming a part of the casing. These

FIGURE 73. FIGURE 74.

Wheel for a Velocity Compounded Stage. l>iai>hragiii — Small Turbine.

96 STEAI^I TURBINES.

bearings are of the usual marine type, water cooled. At the forward end of
the turbine is a small adjusting block to retain the rotor in its proper position
fore and aft in relation to the casing. The bearings and adjusting block are
omitted in PLATE VI.

Casing. The casing is made of cast steel and may be in from two to four
pieces. The casing is split fore and aft by a longitudinal plane through the
axis. The upper and lower halves are secured together by means of a flanged
joint. The casing is grooved on the inner surface where necessary to receive
the guide blades for each velocity compounded pressm'e stage.

Diaphragms. Between each two pressure stages is a diaphragm,
FIGURE 74. This is necessary to prevent steam leakage from one pressure
stage to the next succeeding one, because of the decrease in pressure as the
steam approaches the exhaust end of the turbine. In the cruising turbine the
diaphragms are in one piece, being placed on the shaft between wheels when
the rotor is assembled. The shaft is free to revolve in the central hole of the
diaphragm. The outer edge of the diaphragm fits into a groove cut in the
inner surface of the casing. When the two halves of the casing are bolted
together, the joints formed by the casing and the outer edges of the diaphragms
are steam tight. The diaphragms are stationary. The nozzles for each pres-
sure stage after the first are machined in the outer rim of the diaphragm. To
prevent steam leakage around the shaft from one pressure stage to the next,
each diaphragm is fitted at its central hole, where the shaft passes through,
with a composition bushing with several knife-edge projections against the
shaft. The clearance between the knife edges and the shaft is very small.
This bushing is in effect a small la])yrinth packing gland, and is held in place
by a forged steel ring bolted to the diaphragm.

Nozzles. The nozzles for pressure stages after the first are machined in
the rim of the diaphragm. The nozzles for the first pressure stage extend only
partially around the periphery. They are machined in a segment of a ring
which is bolted in place on the inner face of the steam chest. The number of
nozzles in the several stages is as follows :

stage. No. of Nozzles Throat Area, Sq. Ins.

1 8 1.576

2 16 2.633

3 40 6.804

4 72 18.241

5 72 22.291

Increasing Volumes of Steam. As the steam passes through each suc-
cessive set of nozzles it is expanded to increase its velocity. Consequently, it
is reduced in pressure by steps from one pressure stage to the next with
increasing volume. To provide for the increasing volume of steam, the nozzles
cover a larger arc of the periphery and the height of nozzles and blades is
increased. At the last pressure stage, the steam admission is through nozzles
extending around the whole periphery of the diaphragm. The height of the
nozzles of the first three stages is one-half inch ; of the last two stages, three-
quarters of an inch.

Shaft Glands. To prevent steam leakage to the atmosphere aroimd the
shaft at the forward end of the turbine where the shaft passes through the cas-
ing and to prevent air leakage into the last pressure stage, shaft glands are

THE CURTIS TURBINE. 97

fitted to the casing around the shaft. The shaft glands are provided with carbon
packing rings, as shown in FIGURE 75. Each gland has several sets of carbon
packing, each set contained in a holder. The carbon rings are cut in segments
and are held in place against the shaft by means of spiral springs around the
outer edge. In addition to the carbon I'ings, a bushing is used in this turbine.
Such steam as leaks through the bushing is led by means of a small pipe to a
pressure stage of less pressure. The shaft gland at the L. P. end of the
turbine is provided with a steam connection through which L. P. steam may
be admitted to an atmulai- space between carbon rings to fonn a steam seal
for the prevention of air leakage to the last pressure stage.

m
Rear ^

FIGURE 75.

Shaft Gland, Cruising Turbine.

Part II.
CURTIS TURBINE OB' SMALL SIZE.
Plate VII.— Main turbine of the TUCKER.

General Description. The ahead and astern turbines are contained in
one casing. The tui-bine shaft is direct connected to the propeller shaft.

The ahead turbine consists of 42 pressure stages. The first three pressure
stages are velocity compounded. The first pressure stage is velocity com-
pounded four times; the second and third pressure stages are each velocity
compounded three times. The wheel of the thii-d pressure stage fonns a pai-t
of the first ahead dinam to which are secured the moving blades of the third
to the ninth pressure stages inclusive. The auxiliary exhaust enters the casing

98 STEAM TURBINES.

after the ninth pressure stage. The 10th to the 4"2d pressure stages are mounted
on the second ahead wheeh The 4th to the 42d stages are simple pressure
stages. The steam flows from forward to aft, and after leaving the 42d
ahead pressure stage exhausts to the condensei*.

ore Kiver ShlrbullillDg C<ir|<,

Rotor in Place in Lower Half of Main Tui'bino — Tucker.

The astern turbine consists of nine pressure stages, the tii-st of which is
velocity compounded four times. Tlic last eight pressui-e stages ai'e simple
pressure stages \\'ith moving blades secured to a drum. The steam flows
through the astern turbine from aft to forward, and after leaving the ninth
pressiire stage e.xhaiists to the condensei-.

Foro IHv.T ShliibulUllnB ri.riJ.

Rotor of Main Turbine — Tucker.

Rotor. The I'otoi- of this tui'ljine is built up of velocity wheels and di'ums
shrunk on a shaft and secured thereto by means of keys and nuts at either end.
The ahead rotor consists of two ^-elocity wheels and two drums. The astern
turbine consists of one velocity wheel and one drum. The third ahead pressure
stage is built as a part of tlie first ahead dnun. The space between the

THE CURTIS TURBINE. 99

two ahead diiinis is to reoeive steam from the auxiliary exhaust. The velodty
wlieels are built up, as shown in FIGURE 76. Each wheel consists of a Imb,

FIGURE 76.

Built-up AMieel for Velocity Oonipouiided Stage.

two discs, and a rim. Tlie rim is gi-ooved to receive the moving blades. The
first ahead drum and the astern drum are bnilt ui> in a similar manner, with :

100 STEAM TURBINES.

hub, rim, and eoniieeting dises. The second ahead dnmi is built up. It
consists of several rings with inner projecting flanges riveted together to form
the rim of the rotor. This rim is secured at each end to wheels. Tlie wheel at

FIGURE 78.

After End of L. P. Ahead Rotor— Tucker.

the forward end is shown in FIGURE 77. It is closed to steam ])assage by
means of a disc riveted to the rim and the hub of the wheel. The after wheel is
shown in FIGURE 78. It is made in one piece with large holes bored in the

101

o of
end
sui-e

nn oam

d to

f L. P.

^^^'- fii-st

;om-
the
zlcs.
£am
it of
Eore,
:lonc

dia-
r;ora-
)the
szles.

dia-
that
team
i arc
sing.
jugh
rt of
:)<dty
td in
tetun
;king
'd in

The
nner

iMdty

each
ados.
czles.
k'hole
)lade
team
- _ isure

ially
)lade
, 64;
• sets

THE CURTIS TURBINE. 101

disc. Referring to PLATE VII, it will be noted that steam of the pressure of
the auxiliary exhaust acts on the forward side of the disc at the forward end
of the second ahead drum, while on the after side of this disc the pressure
is practically the same as that in the condenser. There is, therefore, a steam
thrust acting on the forward side of this disc. This steam thrust is used to
oyercome propeller thrust.

Velocity Compounding. A cross-section through the blading of the first
pressure stage is sliown in FIGURE 79. This pressure stage is yelocity com-
pounded four times; that is, it has foiu* rows of moying blades to absorb the
yelocity deyeloped by the steam in expanding through the first set of nozzles.
The nozzles are formed of a segment of a ring which is bolted to the steam
chest. The guide blades are secured in the grooyes formed in a segment of
a ring bolted to the inncn* side of the casing. Steam admission is, therefore,
aroimd only a part of the periphery of the first pressure stage. This is done
in order that the blade heights will not be too small.

The first and second pressure stages are separated by means of a dia-
phragm, as shown in FIGURE 80. The second pressure stage is yelocity com-
pounded three times ; that is, it has three rows of moying blades to absorb the
yelocity deyeloped by the steam in expanding through the second set of nozzles.
The nozzles are formed of a segment of a ring which is bolted to the first dia-
phragm. This segment occupies a larger arc of the periphery than does that
forming the first set of nozzles, because of the increased yolume of steam
produced by expansion through the first set of nozzles. The guide blades are
secured in grooyes formed on the inner surface of the upper half of the casing.

The steam flows from the second to the third jH'essure stage through
nozzles which are secured to an inwardly proje(*ting flange forming a part of
the first section of the casing, as shown in FIGURE 81. This stage is velocity
compounded three times. The three rows of moying blades are secured in
grooves cut in the forward part of the first ahead drum. To prevent steam
leakage past the forward edge of the drum, a few rings of labyrinth packing
are used. Such steam as leaks through this labyrinth packing is utilized in
the first pressure stage of the second ahead drum (see PLATE VII). Tlie
guide blades of this pressure stage are secured in grooves fonned on the inner
surface of the upper half of the casing.

Simple Pressure Stages. The first three pressure stages are velocity
compounded and are followed by pressure stages to the turbine exhaust, each
of which consists of one row of guide blades and one row of moving blades.
The guide blades in these pressure stages form buckets which act as nozzles.
Beginning with the fourth pressure stage, steam admission is around the whole
periphery. Hence, to allow^ for the increasing volumes of steam, the blade
heights are increased towards the exhaust end of the ahead turbine. Steam
leakage will take place over the tips of the guide blades from one pressure
stage to the next, where the drum construction is followed. This is partially
prevented, however, l)y the extending rims on the strips secured to the blade
tips. The number of nozzles in the fii*st stage is 20; in the second stage, 64;
in the third stage, 106. The throat area in square inches in the first three sets
of nozzles is respectively 11.42, 22.68, and 37.40.

102 STEAM TURBINES.

Diaphragms. The diaphragms hetweeii the fii-st and second, and
second and third pressure stages are similar in constrnction to the diaphi-ag
of the crnising tnrbine. The bushings to prevent steam leakage around
shaft from one pressui'e stage to the next are secured by means of set scrt
in grooves around the inner side of the diaphragm hxibs.

Casing. The casing is divided into halves by a horizontal plane throu
the axis. The two halves are connected by a tianged joint so that the toi>
the casing may be lifted for an examination of the interior of the turl)ii
Each half of the casing is built \\\) of eight castings, in order to insure sou.
metal. AVhen assembled, the casing contains both the ahead and the aste
tui'bines.

Fiiiv lllTcr ShipbiiUdlDS Corp.

Lower Half of Casing of Main Turbines — Tucker.

Astern Turbine. The astern turbine consists of nine pressure stage;
The first pressure stage is velocity compounded four times. That part of tl"
easing to which are secured the guide blades for the last eight pressure stag*
is secured to the ahead casing by means of a flange inside the turbine casin
under the exhaust to the condenser.

Shaft Glands. The shaft glands are similar in design and coustructio
to those of the cruising turbine. The leakage of steam past the bushing of th
forward stuffing box is led to the same space to which the auxiliary exhau&
is connected, and is utilized in the fii'st pressure stage on the second ahea-
drum, or in the KXh pwssure stage of the tui'bine.

1 S FIGURE 80.

cond Pressure Stage Velocity
Compounded Three Times —
lain Ahead Turbine — Tucker.

102

Dial

second a
of the e
shaft frc
in groov
Ca«i
the axis,
the casi] ,
Each ha
metal,
turbines

The fir
casing
is seen:
under ■
Sh
to thos
for^var
is com
Mjjkdrum,

IRE 81.

re Stage Velocity
Three Times-
Turbine — Tucker.

/
/
/

102

Di)

second

of the

shaft :

in gro

the a:

the c

Each
niet«'
tnrh

of
ker.

of
sh

th
th

-J>^

THE CURTIS TURBINE.

■■■r Shl|.lnill.nnc n.rp. F'TC HIvt Sbli>l>ii11rllnc Com.

View of Foi'ward End of Main \'ie\v of Aftor EikI of Main

Tnr»)ine — Tucker. Turbine— Tnt-ker.

104 STEAM TURBINES.

Part III,

CURTIS TURBINE OF LARGE SIZE.

Plate VIII.— The H. P. ahead turbine of the NEVADA.

Plate IX.— The L. P. ahead and astern turbine of the NEVADA.

H. P. Turbine. Both the H. P. and the L. P. turbines are direct con-
nected to the propeller shaft. The H. P. turbine consists of five velocity
compounded pressure stages and 25 simple pressure stages. The first pressure
stage is velocity compounded four times. The succeeding four pressure stages
are each velocity compoimded twice. The moving blades of the 6th to the ] 4th
pressure stages are secured to a drum. The fifth pressure stage wheel is
secured to and fonns a part of this drum. The moving bhides of the 15th
to the 30th pressure stages are on a second drum. The steam exhausting from
the 14th stage flows through a pipe, connected to this stage at the under side
of the casing, to the after end of the casing. The steam flow in the first 14
pressure stages is from forward to aft; the steam flow in the 15th to the 30tli
pressure stages is from aft to forward. The steam thrust obtained on the
forward end of the first drum is thus partiall}^ balanced by the steam thrust
on the after end of the second drum.

L. P. Turbine. The L. P. ahead turbine and astern turlnne are contained
in one casing. The L. P. ahead turl)ine consists of 38 simple pressure stages.
The moving blades of these stages ai-e secured to a drmn. The steam flow is
from forward to aft. The increasing vohunes of steam due to expansion are
alloAved for by increasing the bhide lieights from the H. P. end to the exhaust
end of the tiu'bine and by increasing the bucket vohmie by decreasing the
blade angle relative to the turbine axis. After exhausting from the last ahead
pressure stage, the steam flows to the condenser tln*ough the main exhaust
pipe.

Astern Turbine. The astern turbine consists of two velocity compounded
pressure stages and eight simple pressure stages. The first pressure stage
is velocity compounded four times. The second pressure stage is velocity
compounded three times. The second stage wheel is a part of the astern drum.
Steam flows through the astern turbine from aft to forward, and after leaving
the last astern pressure stage exhausts to the condenser.

Cruising Turbine. Each cruising turbine is a three pressure stage
turbine. The first stage is velocity (compounded twice, and the second and
third stages are simple pressure stages each with one* row^ of moving blades.

The casings of the cruising turbines are of cast steel. Each casing is
divided into two parts on the horizontal center line.

Nozzles for the first stage are of composition, and are set^ured on the
inside of the upper section of the casing head. There are 15 nozzles for the
first stage. Nozzles for the second stage are of composition w^itli monel metal
division plates, and are carried by the diaphragm. There are 48 nozzles for
the second stage. Nozzles for the third stage are cast in the diaphragm and
have nickel steel division plates. Tliere are 48 nozzles for the third stage.

Rotors. The H. P. rotor consists of a shaft on which are secured four
velocity compounded pressure Avheels and two drmns. These are held in place
by nuts screwed on the shaft at either end and prevented from turning by
set screws.

THE CURTIS TURBINE. 105

The L. P. rotor consists of a shaft with one drum for the ahead moving
blades. The drmn, FIGURE 82, is built up of rings with inside flanges riveted
together. The rings when assembled form the rim of the rotor. The drmn
is secured to a wheel at each end. Each wheel consists of a hub with several
outwardly projecting brackets. A disc connects the hub of each wheel to the
drum.

The astern turbine has one velocity compoimded pressure wheel and a
drum secured to the same shaft as the L. P. ahead turbine. The drum is built
up of rings with inside flanges riveted together to form the rim of the rotor.
The drum is connected to a wheel hub secured to the shaft by means of a disc
at each end of the drum.

The wheels of the compounded pressure stages are of the built-up type,
as shown in FIGURE 83.

Diaphragms. Separating the velocity compoimded pressure stages are
diaphragms built up, as shown in FIGURE 84. The diaphragm consists of
a hub and a rim to both of which is riveted a dished disc. Nozzles are secured
to flanges projecting inwardly from the turbine casing. The diaphragms,
therefore, extend from these flanges with which they make steam-tight joints
to the shaft. Where the shaft passes through the diaphragm, a composition
bushing with inwardly projecting knife edges is secured. This bushing is in
effect a labyrinth packing gland which prevents leakage of steam from one
pressure stage to the next.

Casings. The casings are of several pieces made of cast iron. They are
strengthened by outside longitudinal and circumferential ribs and are split
in two parts by a horizontal plane through the turbine axis. The two parts
thus formed are connected by a bolted flanged joint. The upper half may be
lifted for an examination of the interior of the turbine.

The part of the casing to which are secured the guide blades of the last
eight pressure stages of the astern turbine is secured to an inwardly projecting
flange near the after end of the L. P. ahead casing. The astern casing projects
forward under the exhaust to the condenser.

Shaft Glands. Where the shaft passes through the casing at either end,
a carbon gland is secured to the casing to prevent steam leakage from the
turbine or air leakage into the turbine, depending on the pressure existing
inside the turbine. The type of shaft gland used is shown in FIGURE 85.
The carbon rings are split in segments. There are two carbon rings held in
place by each set of holders. Each set of holders consists of a number of
built-up segments, as shown in detail in FIGURE 85. Each segment holder
has riveted to its outer surface a flat spring which holds the carbon against
the shaft, and has riveted to its side surface a flat spring which keeps the
holder and carbon in its proper fore and aft position.

The gland at the H. P. end of the H. P. turbine is provided with a com-
position bushing secured to the casing. Steam that leaks through this bushing
is led to a stage of lower pressure.

106 STEAM TURBINES.

Center Line^7

FIGURE 83. FIGURE 84.

Built-up Wheel for Velocity Diaphragm — H. P. Tur-
Gompounded Stage. bine — Nevada.

;

'I-

I-w

/ m

FIGURE 86.

Shaft Gland— H. P. and L. P.
Turbines — Nevada.

Elevation

Shaft Sleeve

'hrough ab
irbon Holder.

Center Line -^

THE CURTIS TURBINE.

107

Pabt IV.
GENERAL DETAILS.

Main Bearings. At each end of the turbine is a main bearing supporting
the shaft. It is outside of the easing, secured to and forming a part of the
casing. It is of the usual marine type of bearing (see FIGURE 86, folder,
p. 112).

Adjusting and Thrust Block. At the forward end of each turbine is a
small thrust block. This is shown combined with the forward main bearing

FIGURE 87.

Impulse Blade.

in FIGURE 86. The thrust blocks are of the usual marine horse-shoe type,
water cooled. Each horse-shoe thrust block can be adjusted independently
by means of nuts on bolts to which it is secured on either side. Provision is
made for circulating water through each horse-shoe block. As the steam
thrust is always in excess of the propeller thrust, the thrust block takes a
large amount of thrust only when starting or stopping so that there is very

108

STEAM TURBINES.

little wear on the bearing surfaces. The thrust block is used principally
to retain the rotor in a fixed fore and aft direction in relation to the casing
to assure proper fore and aft clearance between moving and fixed blades.

Blading. The blading of the latest Curtis turbines is secured to the
casing, wheels, and drums by insertion in grooves of dovetailed cross-section.
The roots of the blades are machined to fit these grooves, as shown in
FIGURE 87. The spacing between blades is adjusted and maintained by
packing pieces with similar root shape and machined to fit snugly the curvature
of the blades, as shown in FIGURE 8& Referring to FIGURE 89, the blades
a and the packing pieces b are inserted in the grooves through a space c
which is widened to allow the root of the packing piece to pass. After the
blades and packing pieces are all inserted, the space c is filled in with a closing

FIGURE 88.

Packing Pieces.

FIGURE 89.

Method of Inserting
Packing Pieces.

90.

Cross-Section of Bucket
Bands or Shrouding.

key. The packing pieces are caulked to secure the blades firmly. The tips of
the blades are shaped, as shown in FIGURE 87, for insertion into holes of the
bucket bands which bind the blades of each row together. The tip projection
is riveted after the bucket band is secured in place. The bucket band is also
known as shrouding. The cross-sectional form of two kinds of bucket bands
is shown in FIGURE 90. That for velocity blades is a; that for drum stages
is b.

Another method of securing blading in Curtis turbines, to be found on
all but the latest ships with these turbines, is blading with a foundation ring.
The blades are milled at the root to fit into holes in a ring of fl-shape,
FIGURE 91. The roots of the blades are riveted at R. The foundation ring,
which is in segments, is sawed as shown at c in order that it may be bent to the
curvature of the casing or rotor. The foimdation ring has serrations a cut
in either side so that when secured to the rotor the edges of the grooves into

THE CUBTIS TURBINE. 109

which the ring fits may be caulked to fill these serrations. The bucket band
or shrouding S is then placed and the blade tips riyeted.

Steam Connectifnis. The steam connections to the turbine casings may
be tabulated as follows:

1. Cruising tiu-bine:

(a) From mala steam-line to the first pressure stage nozzles.

(b) From main steam-line to the first pressure stage compartment.

(d) Exhaust pipe from last pressure stage compartment to the H. P.
turbine.

(e) Relief valve and pressure gage connections to the first pressure
stage compartment.

FIGURE 91.

Impulse Blades with Foundation Ring.

2. H. P. turbine:

(a) Two exhaust inlets from the cruising tiu-bine.

(b) From main steam-line to first pressure stage nozzles.

(d) Exhaust from 14th pressure stage to 15th pressure stage.

(e) Exhaust from 30th pressure stage to L. P. turbine.

(f ) Relief valve and pressure gage connections to first pressure stage
compartment.

(g) Warming-up pipe to first pressure stage compartment and one
to 15th pressure stage.

110 STEAM TURBINES.

3. L. P. turbine:

(a) Two exhaust inlets from the H. P. turbine to first L. P. stage.

(b) Auxiliary exhaust inlet to the first pressure stage.

(e) Relief valve and pressure gage connections for the first pressure
stage.

(d) Warming-up connection for first pressure stage and one for the
first pressure stage of astern turbine.

(e) Main exhaust pipe for the ahead and the astern turbine to the
main condenser.

Drain Connectioiu. Drain connections may be tabulated as follows :
1. Cruising turbine:

(a) A drain-pipe for each pressure stage.

FIGURE 91a.

Curtis Turbine — New Mexico.

2. H. P. turbine :

(a) Drain-pipe for each of the first four pressure stages.

(b) Drain-pipe for the pressure stages on the first ahead drum.

3. L. P. turbine:

(a) Drain for ahead turbine and for pressure stages on drum of
astern turbine under main exhaust pipe.

(b) Drain for first pressure stage of the astern turbine.
Drain-pipes are led to the suction of the wet air-pump through a common

connection. This connection has a U-bend to act as a water seal, and a light
loaded non-return valve. Drains may also be opened to the bi^.

THE CURTIS TURBINE. Ill

NEW MEXICO'S Turbines (FIGURE 91a). There are two Curtis tur-
bines on the NEW MEXICO, used for driving the A. C. generators. They are
manufactured by the General Electric Company.

Each turbine consists of 10 pressure stages. The first pressure stage is
velocity compounded twice. The moving blades of each pressure stage are
moimted on a wheel secured to the shaft. The pressure stages are separated
by diaphragms which contain in the rim the nozzles for each succeeding pres-
sure stage. The nozzles for the first pressure stage are built in a segment and
are secured to the turbine casing head.

This turbine rims at 2130 revolutions at full speed causing the A. C. gen-
erator to develop 11,400 K. W. Speed regulation of the turbine is accom-
plished by controlling by throttle valves the amoimt of steam to the nozzles
of the first pressure stage and by steam admission to the nozzles of the fifth
and ninth pressure stages (see FIGURE 106).

FIGURE 86.

Curtis Adjusting Block.

FIGURE 86.

Curtis Adjusting Block.

J I

A**

t*" ■

I
, ■ I

PLATE VI.

Curtis Cruising Turbine — Tucker.

* • < ^

. *

i**

PLATE VL

Curtis Cruising Turbine — Tucker.

i '

t t

k-'

J .

r:*

■ ^ ■ ■

FIGURE 86.

Curtis AdjuBting Block.

PLATE VI.

Cui*tis Cruising Turbine — Tucker.

■ I

PLATE Vn.

f Curtis Main Turbine — Tucker.

i
1

■

CHAPTER X.
MIXED OR COMBINED TURBINES.

Introduction. The principles of pressure staging and velocity compound-
ing are applicable to the impulse turbine only. The units for marine propul-
sion have the first few pressure stages velocity compounded, and the remaining
pressure stages are simple pressure stages.

The compound reaction principle is applicable only to the reaction turbine.
This turbine, used for marine propulsion, is comparatively long in order to
increase the length of the path of steam flow and hence reduce the peripheral
blade speed.

In the evolution of turbine design, turbines have been constructed to
combine both the impulse principle and the reaction principle. These turbines
are known as mixed or combined turbines. The form in which these turbines
have appeared in practical use is usually as follows: One impulse pressure
stage velocity compoimded is used at the H. P. end of the turbine. This is
followed by several reaction expansions, from the last stage of which the steam
exhausts to the condenser. The turbine may be contained in one casing, or,
if the unit is a large one, it may be divided into a H. P. turbine and a L. P.
turbine.

None of these turbines have so far been adopted for use in the U. S.
Naval Service, but as the type is coming into use for marine propulsion, and
represents an important part of turbine development, two types likely to be
found in American ships in the future are briefly described. These types are
the Parsons, which is controlled by the Parsons Marine Steam Turbine Co.,
and the Westinghouse, which is controlled and manufactured by the Westing-
house Machine Co.

Parsons Combined Turbine (FIGURE 92). The unit sho^vn here con-
sists of an ahead turbine and an astern turbine contained in one casing.

The ahead turbine consists of one impulse pressure stage velocity com-
pounded fom* times, followed by seven reaction expansions. The velocity
wheel of the impulse pressure stage is secured to the forward end of the reac-
tion rotor whidi is built up in the usual manner. with drum, wheels, and
fonvard and after sections of shafting. The velocity wheel has a drum pro-
jection on its forward end forming the dummy piston. This revolves inside
a cylinder attached to the casing. On the dummy piston and cylinder the
dummy packing is secured to prevent steam leakage from the impulse pres-
sure stage to the inside of the reaction drum.

The astern turbine consists of one impulse pressure stage velocity com-
pounded four times. The construction of velocity wheel and dummy piston
is the same as for the ahead turbine. The impulse pressure stage is followed
by two reaction expansions, from the last stage of which the steam exhausts
into the condenser.

113

114 STEAM TURBINES.

Westinghoute Combined Turbine (FIGURES 93 and 94). This turbine
consists of a H. P. unit and a L. P. unit. Each unit has an ahead and an
astern turbine in the same casing.

The H. P. ahead turbine consists of one impulse pressure stage velocity
compounded twice. This pressure stage is followed by tvvo reaction expan-
sions. Prom the last reaction stage, the steam flows to the H. P. end of the
L. P. ahead turbine.

The H. P. astern turbine consists of one impulse pressure stage velocity
compounded twice. From this pressure stage the steam exhausts to the L. P.
astern turbine. In the H. P. turbine, it is necessary to have separate exhausts
for the ahead and the astern turbines. These are shown on FIGURE 93, C
for the ahead turbine and E for the astern turbine. These two exhaust cham-
bers are sealed from each other by labyrinth packing around the rotor between
the two turbines.

The L. P. ahead turbine consists of five reaction expansions. The steam
is expanded through these from a pressm^e of 24 pounds per square inch
absolute at F to condenser pressure at H. The steam exhaust for the ahead
turbine is from C, FIGURE 93, to F, FIGURE 94.

The L. P. astem turbine consists of one impulse pressm'e stage velocity
compounded twice. Steam exhausts from E, FIGURE 93, to G, FIGURE 94.
The steam, after passing through the L. P. astem turbine, exhausts through
H to the condenser.

The dmnmy packing at the ahead end of each turbine is of the Parsons
type with axial clearance. Leakage from the astern pressure stages is mini-
mized by the use of glands where the shafts pass through the casings. Shaft
glands are also installed around the shafts where they pass through the casings
at the ahead ends of the turbines.

MIXED OB COMBINED TUBBINES.

rrTiMnll '"'''' ■**" ""•"" ' 1" <>«'" •i.MI T»«.».

FIGURE 93.

Westinghonse Combined H. P. Turbine.

FIGURE 94.

Westinghouse Combined L. P. Turbine.

116

STEAM TURBINES.

Blading. Impulse blading is secured as shown in FIGURE 95. The blade
root is dovetailed. After being inserted in the rotor and casing grooves, the

FIGURE 96.

Westinghouse Impulse Blades.

blading is wedged at the side, and the tips of the blades are secured and spaced
by the use of shrouding.

Reaction blading is secured as shown in FIGURES 96 and 97. The blading
is inserted in the grooves with packing pieces between each two blades. The

MIXED OR COMBINED TURBINES.

(b) (c)

FIGURE 96.

Wcstingliouse Reaction liladi's.

parking pieces are ddvetailed at the roots.
After the blades and packing pieces are
inserted, they are secnrcd in jjlace hy wedges
at the side. Lacing of cross-section shown
in a, FIGURE 96, is used to se<ure the tips
of the blades. After the lacing is inserted
and the blades are i)roperh' spaced, the pro-
jecting part of the lacing is caulked over
between the blades, as shown in b and c,
FIGURE 96.

Plan Arrangement of Turbines. The
Westinghouse turbine here described is
installed in a single screw ship. Each tur-
bine is connected through a double reduc-
tion gear to the main gear-wheel on the
propeller shaft.

FIGURE 97.

Westinghouse Reaction Blades.

• ■ - s

I'.i *

L ■'

I-
I '

•I'

III;

CHAPTER XI.
HEAT LOSSES. SUPERHEAT.

HEAT LOSSES.

Turbine Speed. Marine turbine installations must be designed with com-
paratively low bucket speed in order to keep within the range of efficiency of
propellers. In order to reduce bucket speed, expansion of the steam must take
place gradually in a large number of stages. This necessitates, in either the
impulse or the reaction turbine, an increase in the munber of blade rows. With
increasing number of blade rows skin friction is increased and greater losses
due to this take place as the steam flows through the turbine.

Pk-opeUer Speed. The propeller is designed to develop thrust to overcome
resistance of the ship. The thrust is transmitted to the propeller by reason
of the differences of pressure existing between the driving face and the back
of the blades, this thrust being established by accelerating a certain mass of
water. There is, however, a limiting velocity with which the water will flow
into the propeller to take the place of that discharged astern. When the
velocity of the astern race, or the difference in the pressure between the back
and the front of the propeller blades, exceeds the limiting value, a vacuous
space will be found at the forward sides of the blades. This phenomena is
known as ** cavitation.'^ Cavitation increases with increase of propeller speed.
Increase of cavitation increases propeller slip or reduces propeller efficiency.
For this reason, the speed of rotation of the propeller can be increased only
up to a certain point without excessive loss in efficiency.

Compromise Between Propeller Speed and Tm'bine Speed. In order to
obtain as high an over-all efficiency as possible of turbine and propeller, the
propeller speed must be increased with graduallv decreasing efficiencv, while
the turbine speed must be decreased with gradually decreasing efficiency until
a point of compromise is reached where the speeds adopted will give the best
possible efficiency for both turbine and propeller. Recent improvement in
propeller design has enabled propellers for destroyers to run at 900 revolu-
tions per minute with 60 per cent efficiency.

Steam Friction Lomos. The reduction in turbine speed leads to the first
and most important loss that takes place in the turbine. As before stated, it
is the increased friction loss due to a large increase of blade surface over which
the steam must pass, and increased internal friction of the steam due to the
steam path being longer from the admission end of the turbine to the
condenser.

Reaction Turbine Lottos. An analysis of the different losses which occur
in the Parsons turbine may be sxmimarized under two heads:

1. Total losses.

2. Partial losses.

119

120 STEAM TURBINES.

Parsons Total Losses. The total losses in the Parsons turbine divided
into a H. P. and a L. P. turbine are as follows :

(a) Leakage over the L. P. dummy.

(b) Leakage through all shaft glands.

(d) Radiation.

(e) Loss by carry over of regenerated heat from L. P. turbine to
condenser.

(f ) Loss due to fan action and friction of rotor wheels in the L. P.
turbine.

These losses amount to from 6 to 12 per cent.

Parsons Partial Losses. The partial losses in the H. P. unit of the
Parsons turbine, which are total losses as far as that turbine is concerned, but
which are utilized in the L. P. turbine, are as follows :

(a) Leakage over H. P. diunmy.

(b) Loss by carry over of regenerated heat from the H. P. turbine.

These losses amount to from 4 to 8 per cent.

The partial losses in both H. P. and L. P. imits, which are being con-
tinuously utilized in the next lower expansion as regenerated heat, are as
follows :

(a) Friction of steam in blade channels.

(b) Leakage over tips of blades.

(d) Friction of steam on walls of casing and on rotor drum.
These losses amount to from 25 to 35 per cent.

Pressure Velocity Compounded Impulse Turbine Losses. An analysis of
the different losses which occur in the Curtis turbine may be arranged under
two heads :

1. Total losses.

2. Partial losses.

Curtis Total Losses. The total losses in the Curtis turbine with one unit
are as follows :

(a) Leakage through shaft glands.

(b) Mechanical friction of bearings.

(d) Loss by carry over of regenerated heat from the last pressure
stage to the condenser.

These losses amoimt to from 3 to 7 per cent.

Curtis Partial Losses. The partial losses in the Curtis turbine, which
are total losses in one stage, but which are utilized in the next lower stage, are
as follows:

(a) Friction of steam in nozzles.

(b) Friction and shock in buckets.

(d) Friction and fan action of wheels, drum, and moving blades.
These losses amount to from 38 to 45 per cent.

HEAT LOSSES. SUPERHEAT. 121

SUPERHEAT.

Superheated Steam. The use of superheated steam for marine turbine
work has not been extensive, but superheating is used considerably in land
installations. Superheat is used with battleships having electric drive where
the turbo-generators are of a size and run at a speed more nearly that of
turbines in land installations. The increased economy obtained by tiie use of
superheated steam is partly due to the fact that no water is carried over with
the steam from the boilers; but economy is chiefly obtained by the fact that
frictional losses in the blading, nozzles, etc., is less in the case of superheated
steam than when the steam is in a wet condition. The increased economy
obtained by the use of superheated steam may be taken to be about from
10 to 12 per cent reduction in the steam consumption, and about from 8 to 9
per cent reduction in the fuel consumption, for every 100° of superheat used.

Disadvantages of Superheat The disadvantages of superheating gen-
erally are:

1. Difficulties in upkeep of superheaters.

2. Distortion of the turbine parts due to the use of high temperatures.

3. Erosion of the blading.

In the case of the Parsons all-reaction turbine, where tip clearance must
be kept as low as possible, the liability to distortion might be considered to be
serious ; but with the Ciui;is turbine, or with turbines with the impulse principle
at the H. P. end, the clearances are not of necessity small, and therefore the
risk of damage due to distortion is very small.

The turbine most likely to cause trouble with high temperatm^es of super-
heated steam is the astern turbine. This is often running for long periods in
a vacuum at low temperatures, after which high temperature steam is suddenly
admitted with liability to unequal expansion of mechanical parts and danger
due to consequent distortion.

Requirements of a Superheater for Marine Purposes. The requirements
of a superheater for marine purposes are:

1. That it should form an integral part of the boiler.

2. That it should be so placed in the path of the boiler gases as to
obtain the required degree of superheat for the steam.

3. That it should be designed to be cut out of use in case of leakage
or failure of a tube.

4. That it should be designed to cease superheating the steam if the
engines are suddenly slowed or stopped.

CHAPTER XII.
TRANSMISSION.

Introduction. In the case of the turbine, the higher the speed of rotation
the greater is the economy of operation. This is coupled with a great reduc-
tion in the size and weight of the turbine. On the other hand, with the screw
propeller, high speeds not only tend to reduction in propeller efi&ciency, but
very quickly reach a limiting value which cannot be exceeded.

With turbine installations for naval ships, it is necessary to obtain as high
an efficiency as possible for turbines and propellers combined, at all speeds
from low cruising speeds to full speed. This is necessary because it is desired
to conserve the fuel supply in order to increase radius of action. High effi-
ciency at low speeds is also necessary because most of the steaming of men-of-
war is done at speeds less than full speed.

Systems of Transmission. In order to meet these demands, transmission
has been developed that will allow the turbine to have relatively high speeds
of rotation. These high turbine speeds are reduced by transmission to speeds
that will give high propeller efficiency. The systems that have met with suc-
cess in their practical application are :

1. The use of a reciprocating engine exhausting to a turbine. Engine
and turbine are direct connected to the propeller shaft.

2. Mechanical reduction through gear-wheels. Turbines may be con-
connected to reduction gears, or a combination may be used consisting of
cruising turbine geared to the propeller shaft for low speeds of the ship
with direct connected turbines for high speeds of the ship.

3. Electrical transmission. Turbines are used for generating current,
and the current is used for propulsion by use in motors direct connected
to the propeller shafts.

4. Hydraulic transmission. This is a combination of a steam turbine
driving a centrifugal pmnp. The energy given the water by this pump is
utilized in driving at reduced speeds a water turbine direct connected to
the propeller shaft.

Reciprocating Engine and Turbines. In this system, one or more recip-
rocating engines are used in combination with one or more turbines. The
steam is used first in the reciprocating engine, and the exhaust from this is
led to the turbine. By means of this system, special advantages in economy
are obtained. The reciprocating engine is more economical in steam consump-
tion than is the H. P. end of the turbine, while the L. P. end of the turbine is
more economical than the L. P. cylinder of the engine. This latter is due
chiefly to the fact that in the turbine a high vacuum can be much more efficiently
utilized. Consequently, in the combination, each type of engine operates for
that portion of the cycle for which it is best adapted, and the final result is
one materially better than with either the reciprocating engine or the turbine
alone.

128

124

STEAM TURBINES.

A modification of this system has been employed on destroyers. With
the Parsons turbines (two shafts) only one reciprocating engine is used,
connected by clutch to the port shaft (see FIGURE 114). With Curtis and
Zoelly tiirbines, there is a reciprocating engine connected to each shaft through

FIGURE 114.

Cununings.

.iTM'ocat'lng- engine

CruislTig^ reclpro-
xing engine

F<rf.

FIGURE 118.

Parker and Duncan.

a clutch (see FIGURE 118). The reciprocating engines are designed to give
the ship a speed of about 16 knots when working in series with the turbines,
and above this speed the reciprocating engines are disconnected and the tur-
bines alone are used.

TRANSMISSION. 125

Mechanical Reduction Gear. This is the simplest of the transmission
systems. It consists of a large gear-wheel on the propeller shaft. Geared to
the large gear-wheel is a pinion on the turbine shaft. The gear-wheels have
helical teeth.

This system gives an eflSciency of transmission of from 98 to 98J per cent.

Its advantages are:

1. Highest mechanical efficiency.

2. Any fixed speed reduction ratio can be used.

3. It is the lightest in weight.
Its disadvantages are :

1. The power transmitted per shaft is limited due to a limit to tiie
size, and hence to the strength, of the gear teeth.

2. The backing power is limited.

FIGURE 113.

Wadsworth.
(See Figure 98.)

WADSWORTH'S Arrangement Mechanical gearing has been used in
two ways. The WADSWORTH type represents an arrangement where the
main turbines are geared to the propeller shafts (see FIGURE 113). It consists
of two turbines in series for each propeller, one H. P. and one L. P. turbine,
each on its own shaft. The shafts of both turbines are geared through pinions
on opposite eddes of the main gear-wheel which is coupled directly to the pro-
peller shaft The steam on exhausting from the H. P. turbine passes to the
L. P. turbine, thence to the main condenser. l%e H. P. turbine is provided with
cruising expansions which may be by-passed for full speed. At the exhaust
end of the L. P. ttirbine, an astern turbine is installed. The main thrust

STEAM TUBBDfES.

I. P. Turbin*
Shaft

D ,. Port

Propeller

Shan

P. Turbine
Shaft

«-Aft

L. P. Turbine
Shaft

tst

Propeller ey.

Shaft

1, P. Turbine
Shaft

FIGURE 98.

Wadsworth Reduction Gear.
(See Figure 113.)

TRANSMISSION. 127

bearing is on the pi-opeller shaft forward of the main gear-wheel. FIGURE 98
shows a plan arrangement of the gear-wheels and pinions. FIGURE 99 shows
the gear-wheels with gear-box cover removed. This arrangement has given
good economy at all speeds.

FIGURE 99.

Port Reduction Gear, Looking Aft — Wadsworth. Upper Casing Removed.

Cruising Turbine Reduction Gear. In this type, the main turbines are
direct connected to the i)roiielI('i* shafts which may be two to four in number.
On the two-shaft ships, the NEVADA and the GUSHING, each propeller shaft
has secured to it at the forward end through a chitch a main gear-wheel (see
FIGURES 110 and 119). Each cruising turbine is geared to the main gear-
wheel through a pinion on the cruising turbine. A side elevation and plan of
the NEVADA'S gearing is shown in FIGURE 100. FIGURE 101 sliows the
gearing with gear-box cover removed. This is a type of double reduction gear.

128

STEAM TURBINES.

Propeller

I
I

Mr-

L.P.and

astern

tuirbine

Main
Condevis

Aft.

Aft€r engine
room

Center* Itne

fi&in
CoY>dens

After engine
room

*-.

shait

L.P.awd

astervk

tarbivia

Main
H.P.

tur'bine

FoYwaxd engixia
room

Forward cncl^a
room

Cruising-
turblyia

Fwd.

Cruising
turbine

FIGURE 110.

Nevada.

(See Figure 100.)

^opeller

SKait

Aft

CgYitcr line

nCwS^^glTffJlM

Pro pell ex

Clutch -.Xeduc- _ ^

TRin:

FIGURE 119.

Cushing.

FIGURE 100.

Reduction Gear — Neva
(See Figure 110.)

130 STEAM TURBINES.

FIGURE 101.

Rt'ductioii Gear — Neva

tie

FIGURE 115.

Conyngham.

TRANSMISSION. 131

On the two-shaft destroyer CONYNGHAM there is one cruising turbine
geared to the starboard propeller shaft. The gearing may be disconnected
from the propeller shaft by means of a clutch (see FIGURE 115). In the
four-shaft an-angement of gearing for the ARIZONA, a cruising turbine is
geared to each outboard shaft and may be disconnected by means of a clutch.
This arrangement of gearing is made up of the main gear-wheel secured to the
propeller shaft, and a pinion secured to the cruising turbine shaft. The plan
view is shown in FIGURE 102.

Propeller
Shaft

Std. Gear
(Port Gear Reversed)

FIGURE 102.

Reduction Gear — Arizona.
(See Figure 109.)

In the four-shaft arrangement of the PENNSYLVANIA, each outboard
shaft is connected to two cruising turbines. The main gear-wheel is secured
to the propeller shaft and may be disconnected by means of a clutch (see
FIGURE 111). The two cruising turbines are geared to opposite sides of the
main gear-wheel by means of pinions on the two cruising turbine shafts. The
plan view of one gear is showii in FIGURE 103. FIGURE 104 shows the gear-
box with cover removed.

Clutch. The clutch used for connecting and disconnecting cruising recip-
rocating engines and cruising turbines must be designed to connect and dis-
connect when the engines are running, and must transmit power without
slipping when the engines are connected up. A type of power clutch found

Propeller
Shaft

4-A

STEAM TURBINES.

FIGURE 103.

(800 Figure 111.)
Rochiction Gear — Pcnnsvlvaiiia.

TRANSMISSION.

FIGURE 104.

Reduction Gear — Pennsylvania.

134 STEAJI TURBINES.

on destroyei-s is shown in FIGURE 105. The clutch is fonnected on tbe right
to the rec'iprocatinji t'njfine r-rank-shaft or to the main gear-wheel shaft. The
driving member of the clutch consists of a circular frame A Iiolted to the
erank-shaft flange and <'arrying a fixed circular friction membei" B, also a
similar but movable fi-iction member C which is permanently attached to the
clut<'h frame thro\igh the flexible diaphragm E. The space between this fric-
tion member C and the frame A of the clutch is made into a closed chamber
G by the head F. This head F is fonned of a steel plate, and the (rhamber G
receives the operating oil which is supplied through tlie axial hole in the engine
cx-ank-shaft. Tlie clutch is shown in released condition. It will be evident

FIGURE 105.

jNIetteu Hydraulic Clutch.

that tlie application of i)ressure to the chamber G will came the extension of
the diaphragm E until the driven disc D is clamped at its periphery between
the friction surfaces on C and B. The driven disc D is attached to the flange
of the propeller shaft. The friction surfaces on C and B are lined with
material similar to that used for automobile l)rake linings. The clutch is
hydraulically oi)eratcd, the pressure medium being oil supplied by the regular
oil pumps for turbine hd)rication.

Electrical Transmission. The general i)rincii»le of this system so far as
it applies to turl)ines is the generation of electric ]K>\ver by means of a high
speed turbnie. and the utilization of the electric current so "generated to drive
comparatively slow running electric motors directlv couph'd to the propeller
shafting.

Electric projiulsion as proposed for the NEW MEXICO consists of two
turbines, each driving a two-pole quarter-phase alternator, and on each propeller

TRANSMISSION.

135

shaft is a double squirrel cage induction motor arranged to be used as either
a 24- or a 36-pole motor. Using 24 poles, the alternator and turbine speed is
12 times the motor speed. Using 36 poles, the alternator and turbine speed
is 18 times the motor speed. This is the principal advantage of electric propul-
sion. It is a two-speed reversible gear between turbines and propellers. Thus,
at full speed and at a normal cruising speed the turbine can be run at its full

vndtor&

PLAN.

C«nt«ir line

Fwd.

ELEVATION.

FIGURE 106.

Electric Drive — ^New Mexico.

speed of 2130 revolutions per minute where its efficiency is highest, while
the speed reduction may be to about 180 revolutions or about 120 revolutions
for the propellers. For other speeds, the turbine and alternator must be
slowed down in the usual manner.

The electric drive is being installed in the NEW MEXICO, and is being
considered for later battleships and battle cruisers. The plan arrangement of
the NEW MEXICO'S machinery for the port side is showTi in FIGURE 106.

136 STEAAI TURBINES.

Speeds up to 18J knots are gotten by the use of only one turbine. Above this
speed, both turbines are used.

The efficiency of transmission of this system is from 91 to 92 per cent.

Its advantages are:

1. Any power can be used per shaft.

2. Most economical at cruising speeds.

3. No astern turbine or transformer needed. Turbine always runs
in the same direction.

4. No starting and stopping of turbine in maneuvering.

5. Full power available for backing.

Its disadvantages are:

1. Less efficient at full powers tlian mechanical gearing.

2. Heavier than gearing and requires more space for installation.

Hydraulic Transmission. The hydraulic transmission has met with suc-
cessful application in the type known as the Fottinger transmitter. A high
speed steam turbine is connected directly to the shaft of a centrifugal pimip.
The w^ater discharged from the pump is led to a w^ater turbine coupled directly
to the propeller shaft. The water turbine is so designed that the energy in the
water causes it to revolve at a lower rate of speed than the pmnp. For prac-
tical application, the pump and the w^ater turbine are arranged in one casing.

The efficiency of the hydraulic system is from 83 to 90 per cent, depending
on the ratio of reduction.

Its advantages are:

1. Any power can be used per shaft.

2. More compact engine arrangement.

3. No astern turbine is needed.

4. Backing power about 85 per cent of ahead power.

Its disadvantages are:

1. Least efficient.

2. Speed reduction limited because of loss of economy with large
speed reductions. A reduction of speed from 6 to 1 is about the limit of
this svstem.

A cross-section of the transmitter is shown in FIGURE 107, The shaft
is fitted with an astern transmitter forward and an ahead transmitter aft.
When the ahead transmitter is in use it is full of water and the astern trans-
mitter is empty. In the case of the ahead transmitter, two water turbine
wheels are used to extract the energy given to the wat(*r by the pump.

The pumps A and E are connected to the steam turl)ine shaft. Water is
ejected from A to the water turbine vanes D. Uj^on leaving D the water
returns to the pump A. When the propeller is reversed by the astern water
turbine, this turbine is full of water and the ahead turbine is empty. Water
is then ej(^cted from E through guide F to turbine G. From G it flows back
to the pump E. The turbines G, B, and D are all connected to the propeller
shaft. The astern turbine wheel G and the ahead turl)ine whec^ls B and D are
all bolted together and (consequently revolve as one.

If both transmitters are empty, the steam turbine shaft carrying the
ahead and astern pump impellers A and E will revolve idly, and no motion

TRANSMISSION. 137

to the propeller shaft will take place. The steam turbine is prevented from
running away by the use of a governor.

The fiUing or emptying of either transmitter when the motion is required
to be reversed is controlled by means of the valve situated under the casing.
The water is supplied by a pump driven off the forward end of the steam
turbine shaft. The valve is horizontal and of the piston type, the position
shown being that occupied when the transmitter is going ahead. The make-up
water from the pump passes from the valve chamber V through passage P,
and thence through the port N to the ahead transmitter. The drain space S
in the astern transmitter is in communication with the valve chamber U which
is open to the drain system. Consequently, the astern transmitter is kept clear
of water. When the valve is drawn forward, the ports U and V are closed, and
the passages T and Q are opened. The valve chamber T is in communication
with the drain space R, in the ahead transmitter, and consequently water is
drained from the ahead transmitter. Owing to the port to the valve chamber
U being closed when the valve is in the forward position, the astern transmitter
can no longer drain, and the make-up water will pass through passage Q to
the astern transmitter and place it in use.

When maneuvering, this valve controls the speeds of the propeller. The
steam turbine is kept running. By slowly moving the valve from the neutral
position, any speed of the propeller can be obtained in either direction. This
is accomplished by opening the water ports only partially and by closing the
drain ports only partially. The transmitter in use is then only partially filled
with water, which results in decreased speed for the water turbine.

CHAPTER XIII.

TURBINE INSTALLATIONS.

The present chapter gives diagrammatic plans for turbine installations
of battleships and destroyers in the U. S. Navy. The sequence of descriptions
follows as nearly as possible the development of the arrangements for both the
Parsons and the Curtis turbines, the older installations coming first. Each
installation described represents a type to be foimd on destroyers or battle-
ships. There may be slight variations from the types described, but these do
not change the essential characteristics of the arrangements of the propelling
machinery.

TABLE B.

PERFORMANCE OF THE SEVERAL TYPE INSTALLATIONS. POUNDS OF WATER PER B. H. P. PER

HOUR FOR ALL MACmNERT.

BattlediiiM.

Dcftroycrs.

•

Parsoni.

Cartii.

Parwma.

Curtis.

ft*
J3

-s

^.S

•

«:

•^

*-^

^3 •••

ner an
Kkton

•

4»

» ft*

•

-fc

•cE

gb.

«k

c^Bm

ghi

ft.

• • • •

22.9

• • • •

21.9

• • • •

• ■ • •

• • • •

• • • ■

■ • • •

• • • •

16.4

• • ■ •

• • • •

14.6

16.2

• • • •

20.5

• • • •

15.4

• • • •

• • • »

• • • •

15.0

• . . •

16.8

• • • •

• • ■ ■

• • • •

35.9

42.3

34.5

• ■ • ■

20.7

28.1

26.9

• • • •

28.3

....

• • • •

20.2

18.2

20.5

■ • • •

21.5

21.2

* • • •

23.3

21.5

• • • •

15.5

• ■ • •

17.9

• • • •

■ • • •

15.1

• • • •

17.4

• • • •

....

• • • •

17.3

16.8

17.6

• • • •

12.7

• • • •

15.5

15.4

• • • •

Full 1
speed J

• • • •

14.1

12.5

15.8

13.7

14.5

17.02

14.8

15.6

* Zoellj turbines.

Mote that the abore performance is in tome cases derired from the trials of a sister ship to the one named.

139

140 STEAM TURBINES.

UTAH. The propelling machinery consists of Parsons turbines arranged
on four shafts, as shown in FIGURE 108. On the inboard port shaft is a
H. P. ahead cruising turbine, and aft of it on the same shaft is a L. P. ahead
and astern turbine. On the starboard inboard shaft is an I. P. ahead cruising
turbine, and aft of it on the same shaft is a L. P. ahead and astern turbine.
The astern turbine is aft of the L. P. ahead turbine, but in the same casing. On
each outboard shaft is a main H. P. turbine, and aft of it on the same shaft
is a separate H. P. astern turbine.

Low Cruising Speeds. For low cruising speeds, steam is admitted to the
IT. P. cruising turbine, exhausts to the I. P. cruising turbine, then exhausts to
tlie main H. P. tiu^bines, then exhausts to the L. P. ahead turbines, then
exhausts to the condensers.

High Cruising Speeds. For high cruising speeds, steam is admitted to
the I. P. cruising turbine, exhausts to the main H. P. turbines, then exhausts
to the L. P. ahead turbines, then exhausts to the condenser. The H. P. cruis-
ing turbine turns idly in a vacuiun.

Full Speed. For full speed, steam is admitted to the main H. P. turbines,
is exhausted to the L. P. ahead turbines, and then exhausts to the condensers.
The I. P. and H. P. cruising tiu^bines turn idly in a vacuum.

Backing. For backing, steam is admitted to the H. P. astern turbines,
exhausts to the L. P. astern turbines, and then exhausts to the condensers.
The ahead turbines all turn idly.

TURBINE INSTALLATIONS.

141

Port iMln H.B.

FIGURE 108.

Utah.

142 STEAM TURBINES.

ARIZONA and IDAHO. The propelling machinery consists of Parsons
turbines arranged on four shafts, as shown in FIGURE 109. The center-
line bulkhead divides the machinery space into two parts. Each half is again
divided into two parts, forming four engine-rooms. The starboard and port
installations are identical, but reversed in arrangement. On the outboard
propeller shaft is the L. P. ahead and astern turbine contained in one casing.
The L. P. astern turbine is under the exhaust pipe to the condenser. The
L. P. ahead and astern turbine is direct connected to the propeller shaft.
Forward of the L. P. ahead and astern turbine is a cruising turbine connected
to the outboard propeller shaft by reduction gear and clutch. On the inboard
propeller shaft is the H. P. ahead turbine, and aft of it on the same shaft is
the H. P. astern turbine. Each has a separate casing, and both are direct
connected to the inboard propeller shaft.

Low Cruising Speeds. For low cruising speeds, the cruising turbine is
connected to the outboard shaft through the reduction gear by means of a
clutch just aft of the reduction gear. Steam is admitted to the cruising
turbine, expands through this turbine and exhausts to the H. P. end of the
H. P. turbine. It expands through the H. P. turbine and then exhausts to
the H. P. end of the L. P. ahead turbine. Steam expands through this turbine
and then exhausts to the main, condenser. The steam is utilized in the cruising
turbine as follows: For 12 knots or less, steam enters the first expansion. For
15 knots to 12 knots, the first expansion is by-passed and steajqi enters the
second expansion. For 17 knots to 15 knots, the first, second, and third expan-
sions are by-passed and steam enters the fourth expansion.

High Cruising Speeds. For speeds slightly greater than 17 knots, the
cruising turbine with its reduction gear is disconnected by means of the clutch.
Steam is admitted to the H. P. end of the H. P. ahead turbine and expands
through this turbine. It exhausts from this turbine and enters the H. P. end
of the L. P. ahead turbine and expands through this turbine. It exhausts
from the L. P. ahead turbine to the main condenser.

Full Speed. For speeds from 19 knots to full speed, steam is admitted
to the third expansion of the H. P. ahead turbine. The first two expansions,
called the cruising expansions, are thus by-passed. Steam expands through
the remaining expansions of the H. P. ahead turbine and exhausts from this
turbine to the H. P. end of the L. P. ahead turbine. After expanding through
the L. P. ahead turbine, the steam exhausts to the condenser. The cruising
turbine is disconnected.

Backing. For backing, steam is admitted to the H. P. astern turbine.
It expands through this turbine and exhausts to the L. P. astern turbine.
After expanding through the L. P. astern turbine, the steam exhausts to the
main condenser.

TURBINE INSTALLATIONS.

143

Main

Csni«HM»

« *l

,-j;

ait«rn

C\wtcW

R«4«Kti*n

IW^t

fV*|Mil«r <K»^4

CrwtstHO

ffl'.«k«a4 tav&H

't«;rb»'M«

(M.

S:e«M

FIGURE 109.

Arizona.
(See Figure 102.)

144 STEAM TURBINES.

NEVADA. The propelling machinery consists of Curtis turbines arranged
on two shafts, as shown in FIGURE 110. On each shaft there is a H. P.
ahead and a L. P. ahead and astern turbine, both direct connected to the
propeller shaft. The L. P. turbine is aft and contains in the same casing
both the L. P. ahead turbine and the astern turbine. The astern turbine is
aft of the ahead turbine. Forward of the H. P. ahead turbine is a cruising
turbine connected to the shaft by means of a clutch and a double reduction
gear with a reduction ratio of 23.85 to 1. The clutch is aft of the reduction
gear.

Crubing Speeds. The cruising turbines are connected by clutch to the
propeller shaft. For speeds below 15^ knots, steam is admitted to the cruising
turbine and exhausts into the first wheel compartment of the H. P. ahead
turbine. After passing through the H. P. ahead turbine, the steam exhausts
into the L. P. ahead turbine. From the L. P. ahead turbine, the steam
exhausts into the condenser. For speeds slightly in excess of 15^ knots, addi-
tional steam is admitted to the steam chest of the H. P. ahead turbine through
a 5-inch pipe from the main steam-line. It is to be noted that the exhaust
from the cruising turbine leads into the first pressure stage of the H. P. ahead
turbine, and therefore does no work in this stage.

High Crubing and Full Speeds. For speeds higher than about 16^
knots, the cruising turbine with its reduction gear is disconnected by means
of the clutch. Steam is admitted from the main steam-line by means of two
9-inch pipes, or a 5-inch pipe, to the steam chest of the H. P. ahead turbine.
After passing through the H. P. ahead turbine, the steam exhausts to the
L. P. ahead turbine, passes through this turbine and then exhausts to the
condenser.

Backing. For backing, the cruising turbine is disconnected by means of
the clutch. Each astern turbine obtains steam as desired by a throttle valve
on a pipe led from the main steam-line. When backing, the ahead turbines
run idly.

TURBINE INSTALLATIONS.

145

Propeller
shaft

I
I

AT-

a€tttrn
turVina

Main

Aft.

Aft€r cnj^ine
room

Center line

After engine
room

Main
H.P.

turbine

Ibrwud emgixie
room

Forirard cncivie
room

Cruising
turbine

Cruisinjr
turbline

FnA.

FIGURE 110.

Nevada.
(See Figure 100.)

^•^4

146 STEAM TURBINES.

PENNSYLVANIA and MISSISSIPPI. The propelling machinery con-
sists of Curtis turbines arranged on four shafts, as shown in FIGURE 111.
The machinery space is divided into two parts by the center-line bulkhead.
On each side of this bulkhead are two engine-rooms separated by an athwart-
ship bulkhead. The port and starboard installations are identical, but reversed
in arrangement. On the outboard propeller shaft, and direct connected to this
shaft, is the L. P. ahead and astern turbine contained in one casing. Forward
of the L. P. ahead and astern turbine are two cruising turbines connected to
the propeller shaft through a reduction gear and a clutch. The reduction gear
consists of the main gear-wheel connected to the propeller shaft by means of
the clutch; and geared to the main gear-wheel, but on opposite sides, are
pinions attached by flexible couplings to the cruising turbine shafts. On the
inboard shaft is the H. P. ahead turbine, and aft of it on the same shaft is
the H. P. astern turbine.

Cruising Speeds. The cruising turbines are connected to the propeller
shaft by means of the clutch. Steam from one cruising turbine passes to the
other cruising tm'bine, then to the H. P. ahead turbine. Prom the H. P.
ahead turbine the steam exhausts to the L. P. ahead turbine, and finally
exhausts from this turbine to the condenser.

High Crubing and Full Speeds. The cruising turbines and reduction
gear are disconnected by means of the clutch. Steam enters the steam chest
of the H. P. ahead turbine, speed being controlled by the munber of nozzles
in use. Steam exhausts from the H. P. ahead turbine to the L. P. ahead
turbine, and from the L. P. ahead turbine to the condenser. •

Backing. For backing, steam is admitted directly to the H. P. astern
turbine. It exhausts from the H. P. astern turbine to the L. P. astern turbine,
arid then exhausts from the L. P. astern turbine to the condenser. When
backing, the cruising turbines are disconnected and the ahead turbines run
idly.

TURBINE INSTALLATIONS.

147

Po^ hiroliClkr 4k#i^$^

C€nta^ Im^

t«»rbin€

tTurbi He

• ft

CruisiHg

• ^ •

-sStU.tii-»V#iUr 5Ua.(fcs-^

C0»l^<VI$^

H-P. aKeaJtorbtne

I 'I

a{t«rn
Turbivie

HP. akeai Tarkine

RedacTtun

:tift<

CruUlHo
Turbm^

irurkme<

FIGURE ^111.

Pennsylvania.
(See Figure 103.)

fvMi

fi^Cftm

148

STEAM TURBINES.

PRESTON. The propelling machinery consists of Parsons turbines
arranged on three shafts^ as shown in FIGURE 112. All turbines are direct
eoimected to the propeller shafts. The center shaft is driven by the main
H. P. turbine with no astern turbine. The starboard shaft is driven bv the
I. P. cruising turbine and one L. P. ahead and astern turbine. The port
shaft is driven by the H. P. cruising turbine and one L. P. ahead and astern
turbine. In the L. P. ahead and astern tui'bines, the L. P. ahead and the
astern turbines are in the same casing, the L. P. ahead turbine being forward
of the astern turbine.

Low Cruising Speeds. For low cruising speeds, steam is admitted to
the H. P. cruising turbine from which it exhausts to the I. P. cruising turbine.
From the I. P. cruising turbine, the steam exhausts to the main H. P. turbine.
From the main H. P. turbine, the steam exhausts to the L. P. ahead turbines,
and from them to the condensers.

FIGURE 112.

Preston.

High Cruising Speeds. For high cruising speeds, steam is admitted to
the I. P. cruising turbine. From this turbine, the steam exhausts to the main
H. P. turbine, and from the main H. P. turbine to the L. P. ahead turbines.
It finally exhausts from the L. P. ahead turbines to the condensers. The
H. P. cruising turbine turns idly in a vacuiun maintained through its drain
connection to the main condenser.

Full Speed. For full speed, steam is admitted to the main H. P. turbine,
and from this turbine it exhausts to the L. P. ahead turbines. It finally
exhausts from the L. P. ahead turbines to the main condensers. The H. P.
cruising turbine and the I. P. cruising turbine turn idly in a vacuum main-
tained through their drain connections to the main condensers.

Backing. The center shaft is not used for backing. Each astern tiu*bine
has a steam connection to the main steam-line to allow of the admission of
steam to the turbine steam chests. The steam is controlled by a throttle on
each turbine steam-line. The L. P. ahead turbines and the cruising turbines
•n idly when backing. Steam exhausts from the astern turbines to the main
idensers.

TURBINE INSTALLATIONS.

Parsons' Turbines of Preston Class Destroyers Assembled on
Sho]) Floor. (See Fifruro 112.)

L. p. Aliead and Astern Turbine. L. P. Ahead and Astern Turbine.

Main H. P. Turbine.

I, P. Cruising Turbine. H. P. Cruising Turbine.

150 STEAM TURBINES.

WADSWORTH. The propelling machinery consists of Parsons tur-
bines mechanically geared to two propeller shafts. Each propeller shaft is
driven through gearing by one H. P. ahead turbine and one L. P. ahead and
astern turbine, as shown in FIGURE 113. The astern turbine is in the same
casing as the L. P. ahead turbine and aft of the L. P. ahead turbine. The
reduction gear consists for each propeller shaft of the main gear-wheel keyed
to the propeller shaft. With each gear-wheel is meshed a pinion on the H. P.
turbine shaft with reduction ratio of 5.54 to 1, and a pinion on the L. P. turbine
shaft with reduction ratio of 3.36 to 1.

Cruuing Speeds. For cruising speeds, steam is admitted in each engine-
room to the first stage of the H. P. turbine. It exhausts from the H. P. tm*bine
to the L. P. ahead turbine, and exhausts from this turbine to the condenser.

Full Speed. Steam is admitted in each engine-room to the first stage of
the fifth expansion of the H. P. turbine. It exhausts from the H. P. turbine
to the first stage of the L. P. ahead turbine, and finally exhausts from this
turbine to the condenser. The first four expansions of the H. P. turbine,
which are called cruising expansions, are not use^ but are by-passed.

Backing. Each astern tiu'bine has a steam pipe leading from the main
steam-line, and takes steam in its first stage from this line. The steam exhausts
from the astern turbines to the main condensers. The steam for each astern
turbine is controlled bv a throttle valve on each of the astern turbine steam-
lines.

TURBINE INSTALLATIONS. 151

FIGURE 113.

Wadsworth.
(See Figure 98.)

152 STEAM TURBINES,

CUMMINGS. The propelling maehinery consists of an installation of
Parsons turbines in combination with a reciprocating engine of the two
cylinder compound tj^e. The engines are arranged on two propeller shafts,
as shown in FIGURE 114. On the port propeller shaft is the L. P. ahead and
astern turbine in one casing. Forward of the L. P. turbine is the reciprocating
engine connected to the propeller shaft by means of a clutch. On the star-
board shaft is a H. P. ahead turbine, and aft of it on the same shaft a H. P.
astern turbine.

Low Cruising Speeds* For speeds below about 16 knots, the reciprocat-
ing engine is connected to the port propeller shaft by means of the clutch.
Steam enters the H. P. cylinder of the reciprocating engine. After passing
through this engine, the steam exhausts to the first stage of the H. P. ahead
turbine. It exhausts from the H. P. ahead turbine to the L. P. ahead turbine,
and from this turbine it finally exhausts to the condenser.

Hi|^ Crubing Speeds. For intermediate speeds, the reciprocating
engine is disconnected by means of the clutch. Steam is admitted to the first
stage of the H. P. ahead turbine. It exhausts from the H. P. ahead turbine
to the L. P. ahead turbine, and finally exhausts from this turbine to the
condenser.

Full Speed. For full speed, steam is admitted to the first stage of the
second expansion of the H. P. ahead turbine. It exhausts from this turbine
to the L. P. ahead turbine. From the L. P. ahead turbine, the steam finally
exhausts to the condenser. The firat expansion of the H. P. ahead turbine,
which is called the cruising expansion, is not used but is by-passed.

Backing and Maneuvering. For backing, steam from the main steam-
line may be admitted to the first stage of either astern turbine. Each has a
separate steam-line with throttle control. The L. P. astern turbine exhausts
its steam through the main exhaust pipe d to the condenser. The H. P. astern
turbine exhausts its steam through the exhaust pipe c connected to the main
exhaust pipe.

When maneuvering, independent operation of the port and starboard
shafts is accomplished by closing a valve in f which closes the exhaust from
the H. P. ahead turbine to the L. P. ahead turbine. A valve in a is then
opened, allowing the H. P. ahead turbine to exhaust through a into c into d
into the condenser. Steam from the L. P. ahead and the L. P. astern turbine
exhausts as before through pipe d to the condenser.

The reciprocating engine, though not used, is not necessarily disconnected
when maneuvering. It is designed to be dragged at about 400 revolutions per
minute without injury.

TUBBINE INSTALLATIONS. 153

FIGURE 114.

Guinmiugs.

154 STEAM TURBINES.

CONYNGHAM. The propelling machinery consists of Parsons turbines
arranged on two shafts, as shown in FIGURE 115. To the starboard shaft
is direct connected the L. P. ahead and astern turbine contained in one casing.
To the forward end of the starboard propeller shaft, a cruising turbine is
connected by means of mechanical reduction gear and a clutch. To the port
shaft, the H. P. ahead turbine and the H. P. astern turbine are direct con-
nected. The H. P. astern turbine is aft of the H. P. ahead turbine.

Low Cruuing Speeds. For speeds below 20 knots, the cruising turbine
is connected to the starboard propeller shaft by means of the clutch. Steam
is admitted to the first stage of tiie cruising turbine and exhausts from this
turbine to the H. P. ahead turbine. Steam exhausts from the H. P. ahead
turbine to the L. P. ahead turbine, and finally exhausts from the L. P. ahead
turbine to the condenser.

High Cruising Speeds and Full Speed. The cruising turbine is discon-
nected from the starboard propeller shaft when revolutions exceed a speed
corresponding to 22 knots. Steam is then admitted to the first stage of the
H. P. ahead turbine and exhausts from this turbine to the L. P. ahead turbine.
Steam finally exhausts from the L. P. ahead turbine to the condenser.

Backing and Maneuvering. For backing, steam may be admitted to
either astern turbine by independent steam pipes with throttle control. The
H. P. astern turbine exhausts to the condenser by an exhaust pipe connected
to the main exhaust pipe. The L. P. astern turbine exhausts to the condenser
through the main exhaust pipe.

For maneuvering, steam is admitted direct to the L. P. ahead or astern
turbines, to the H. P. ahead or astern turbines, and exhausts direct from
turbine to condenser. Non-return valves are fitted between the cruising tur-
bine and the H. P. ahead turbine and between the H. P. ahead turbine and
the L. P. ahead turbine. Between the H. P. ahead turbine and the L. P. ahead
turbine, a large valve is fitted in the H. P. ahead turbine exhaust to permit
the exhaust from this turbine to be closed to the L. P. ahead turbine and
opened to the condenser.

The H. P. turbine has a by-pass fitted to carry steam to the second
expansion.

Note. — This installation is reversed in the JACOB JONES; that is, the
cruising turbine and the L. P. ahead and astern turbine are on the port shaft,
and the H. P. ahead and astern turbines are on the starboard shaft. The
main condenser is located between the L. P. ahead and astern turbine and the
H. P. astern turbine. These differences are not sufficient to change the classi-
fication of the installation from that included imder the CONYNGHAM type.

TUEBINE INSTALLATIONS. 155

tloB

e«r

t-'iCURE: 116.

Conynghani.

156

STEAM TURBINES,

CONNER and STOCKTON. The propelling machinery consists of Par-
sons turbines arranged on three shafts, as shown in FIGURE 116. On each
outboard shaft is a L. P. ahead and astern turbine. The L. P. ahead and
astern turbines are in each case included in the same casing. On the center
shaft is the H. P. ahead turbine. Forward of the H. P. ahead turbine is a
cruising turbine connected to the center shaft by means of a reduction gear
and clutch.

Low Cruising Speeds. For low cruising speeds, the cruising turbine
is connected to the center shaft by means of a clutch. Steam is admitted to
the first stage of the cruising turbine, and exhausts from this turbine to the
first stage of the H. P. ahead turbine. The exhaust from the H. P. ahead
tiu'bine flows to both the L. P. ahead turbines, and these turbines exhaust to
the condensers.

St rsm

FIGURE 116.

Conner and Stockton.

His^ Cruuing Speeds. The cruising turbine is disconnected by means
of the clutch. Steam enters the first stage of the H. P. ahead turbine, and
exhausts from this turbine to both the L. P. ahead turbines. The steam
exhausts from the L. P. ahead turbines to the condensers.

Full Speed. The cruising turbine is disconnected by means of the clutch.
Steam is admitted to the first stage of the second expansion of the H. P. ahead
turbine. The first expansion of this turbine is by-passed. Steam from the
H. P. ahead turbine exhausts to the L. P. ahead turbines, and finally exhausts
from these turbines to the condensers.

Backing and Maneuvering. For backing, steam is admitted direct from
the main steam-line to either astern turbine, and exhausts from the astern
turbines to the condensers. The astern turbines may be used independently of
each other.

For maneuvering, the H. P. ahead turbine is not used. Steam is admitted
direct to each of the L. P. ahead turbines through independent steam pipes

TURBINE INSTALLATIONS.

157

with throttle control. Each of the astern turbines and each of the L. P. ahead
turbines may be used independently as required.

PERKINS and MAYRANT. The propelling machinery consists of
Curtis turbines for the PERKINS class and Zoelly turbines for the MAYRANT
class. The turbines in both classes are direct connected to two propeller shafts,
as shown in FIGURE 117. Each main turbine includes the ahead turbine and
the astern turbine both in the same casing.

Curtis:

Low Cruising Speeds. For speeds of about 16 knots and less,
only two cruising nozzles in the first stage are used.

High Cruising Speeds. For intermediate speeds, four to nine
nozzles of the first stage are opened.

Aft C^ntei* 11yi£

FIGURE 117.

Perkins and Mayrant.

Full Speed. For full speed, from 15 to 17 nozzles of the first
stage are opened.
ZoeUy:

Low Cruising Speeds. For low cruising speeds, the first stage
throttle only is opened 3i inches.

High Cruising Speeds. For intermediate speeds, the first stage
throttle is opened Si inches, and the fourth stage throttle is opened
6 inches.

Full Speed. For full speed, the first stage throttle is opened 3^
inches, the fourth stage throttle is opened 6 inches, and the sixth
stage throttle is opened 7^ inches.

Backing (both classes). The backing turbines are in the after end
of the main turbine casings. Each backing turbine has its o\\'n steam con-
nection from the main steam-line. Steam is controlled by throttle valves.

158

STEAM TURBINES.

DUNCAN and PARKER. The propelling machiner}' consists of Curtis
turbines on the DUNCAN class and Zoelly turbines on the PARKER class.
The turbines are direct connected to tw'o propeller shafts, as shown in
FIGURE 118. Each main turbine includes the ahead turbine and the astern
turbine in one casing. Forward of the turbine, on each shaft, is a reciprocating
engine of the two cylinder compound type. This is brought into use by means
of a power controlled clutch of the friction t3rpe aft of the engine. This clutch
allows the engines to be connected or disconnected without slowing down.

Low Cruising Speeds. For speeds of 15^ knots and less, the recipro-
cating engines are used in connection with the main ahead turbines. The
steam after being used in the reciprocating engines exhausts to the first wheel
compartment of the main ahead turbines, and finally exhausts from these
turbines to the condensers.

FIGURE 118.

Duncan and Parker.

High Cruising Speeds. At intermediate speeds, the reciprocating engines
are disconnected by means of the chitches. Steam is admitted to the inter-
mediate ahead steam chest and throttled to suitable pressure for the speed
desired. Steam exhausts from the turbines to the condenser.

Full Speed. For full speed, the reciprocating engines are disconnected.
Steam is admitted to the full ahead steam chest of the main ahead turbines.
Steam exhausts from the turbines to the condensers.

Backing. When backing, the reciprocating engines are disconnected.
Steam is shut off from the main ahead turbines and admitted as required to
the astern turbines, from which it exhausts to the condensers.

Backing Variation. On the DUNCAN class, the reciprocating engines can
be used for backing. In this case, the steam from the reciprocating engines
is exhausted into the astern turbines.

TURBINE INSTALLATIONS.

159

GUSHING. The propelling machinery consists of Curtis turbines
arranged on two shafts, as shown in FIGURE 119. Each main turbine
includes the ahead turbine and the astern turbine direct connected to the
propeller shaft. Each propeller shaft has geared to it a cruising turbine by
means of a clutch and a mechanical reduction gear with reduction ratio of

7.95 to 1.

Low Cruising Speeds. For speeds of 16 knots and less, the cruising tur-
bines are connected to the propeller shafts and are used in connection with the
main ahead turbines. The steam is admitted to the cruising turbines and
exhausts from them to the main ahead turbines. It exhausts from the main
ahead turbines to the condensers.

bropell^r

3:Ka7f

Aft

Center line

TOitcW^lrSir ' a^tSg

grcp»13ic

itXATbltie

TKm

IW.

FIGURE 119.

Gushing.

High Cnusing Speeds. For intermediate speeds, the cruising turbines
are disconnected. Steam is admitted to the main ahead turbines, the speed
being controlled by the niunber of nozzles in use in the first stage. Steam
exhausts from the main ahead turbines to the condensers.

FuU Speed. For full speed, the cruising turbines are disconnected.
Steam is admitted to the main ahead turbines, with practically all of the first
stage nozzles open. Steam exhausts from the main ahead turbines to the
condensers.

Backing. When backing, the cruising turbines are not used. Steam may
be supplied from the main steam-line to either astern turbine as desired.
Steam is controlled by throttle valves. The exhaust from the astern turbines
is to the condensers.

CHAPTER XIV.
TURBINES FOR AUXILIARY MACHINERY.

Turbines of SmaU Sizes. Besides the turbines used for the motive power
of ships, there are several turbines manufactured for the purpose of driving
generators, forced draft blowers, and centrifugal pumps. These turbines are
naturally of small sizes. The nature of the work they perform allows a high
speed of rotation with a comparatively short steam path.

Principle Used. The reaction principle is unsuited for small turbines
on accoimt of the high ratio of bucket velocity to steam velocity, and hence
the large number of stages necessary to reduce the speed sufl&ciently for direct
connected units. With increase of stages, tip leakage is abnormally increased.
A large number of stages increases friction losses and tip leakage with con-
sequent decrease in efficiency. Other disadvantages of the reaction principle
are the difficulty of providing for partial admission of steam with economy
of operation at speeds lower than the designed full speed, the necessity for
short blades in the H. P. stages, which makes tip leakage accoimt for a large
proportion of the high-pressure steam, and the necessity of admitting high-
prepare steam into contect with the rotating parte and ^e casing.

The impulse turbine is therefore used for small imits. Velocity com-
poimding in one stage, and velocity and pressure compoimding are the prin-
ciples used.

Brief descriptions will be given of the auxiliary turbines foimd in the
U. S. Navy. The identifying names are necessarily those of the manufacturers
of the various turbines used, though the impulse principle is used in all the
units described.

161

162 STEAM TURBINES.

Part I.
DE LAVAL TURBINES.

Vdodtjr Compounded Turbine. This turbiDe is manufactured by the
De Laval Steam Turbine Company. Minor variations in construction result
from the purpose for which the turbine is to be used.

A cross-section of the turbine is shown in FIGURE 120. The mechanical
parts are the casing to which the nozzles and guide blades are attached, the
rotor which is made up of three velocity wheels to which the moving blades are
attached, the wheels which are secured to the shaft, the shaft which is supported
by bearings at either end of the turbine, the adjusting block which is attached
to the casing for fixing the plane of rotation of the moving blades, the shaft

FIGURE X20.

De Laval Velocity Compounded Tui'bine.

coupling which couples the rotor to the machine to be driven, the shaft glands
which prevent steam leakage where the shaft passes through the casing, and
the governor which controls the steam admission and hence the speed of the
rotor.

The method of attaching the wheels to the shaft is shown in FIGURE 121.
.Each wheel is secured to the shaft by a Woodruff key. The wheels are spaced
and centered by rings. The complete set of wheels and rings is held in place
on the shaft by a heavy nut.

A cross-section of the wheels thi'ough guide blades and nozzles is shown
an FIGURE 122. The wheels are encased in a steel retaining ring which sur-
rounds the wheels and to which the guide blades are attached.

TURBINES FOE AUXILIARY MACHINERY.

figure: 121.

Method of Attaching Wheels.

FIGURE 122.

Section Through Blades.

164 STEAM TURBINES.

Tilt' arraiigciiu'iit of nozzles and blarlcs is shown in diagram in FIGUR£
123. Only two rows of moving blades and one row of guide blades are shown.
The steam is first completely exjianded from initial to exhaust pressure in a
single set of nozzles (see also FIGURE 1201. The jet of steam is directe<l by
the nozzles against the fii-st row of moving blades, from which it is deflected
from its r)riginal direction into a i-ow of guide hni-kets wliich again change its

FIGURE 123.

Arrangement of Nozzle and LJlading.

direction and discharge it against a second row of moving blades. From the
se.-ond row of moving Idades. the steam is deflected from its orighial direction
into a sci'oud row of guide l)nckets. This second row of guide buckets dii'octs
tlic steam against a tliird row of moving blades. Fi-oni the third row of nioviug
blades, the steam jiasses to the B|)ace inside the easing and then to the exhaust.
Thv pressure fj-oni the time the steam leaves the nozzles until exit from the
tnibine is practically constant and equal to the exhaust pressure. The velocity

TURBINES FOR AUXILIARY MACHINERY.

165

at exit from the last row of moving blades, where three rows of moving blades
are used, is approximately equal to the nozzle exit velocity less six times the
blade velocity.

Since the steam is expanded completely from initial pressure to terminal
pressure in the one set of nozzles of a velocity stage, no parts of the casing
except the steam chest, and no rotating parts, are subjected to steam at tem-
peratures higher than that corresponding to the exhaust pressure. This
results in freedom from distortion, and hence an absence of vibration.

FIGURE 124.

Types of De Laval Nozzles.

The nozzles employed are solid bronze castings, in which the steam orifice
is carefully bored and reamed to the shape necessary to secure the desired
ratio of expansion and the delivery of the steam jet free from turbulence and
having all elements truly parallel. These nozzles communicate with a steam
chest cored in the wall of the casing, and are held in place by nuts aiid scaled
copper gaskets. They are easily removed if it is ever desired to replace them,
as in case the turbine is to be operated under steam conditions entirely dif-
ferent from those for which it was originally designed. Nozzles for different
ratios of expansion are shown in FIGURE 124.

166 STEAM TL'KBIXES.

Pkewure CooipoundeJ Turbines. The general airangeinent of this tur-
bine is shown in FIGURE 125u It is manufactured by the De Laval Steam
Turbine Company. The mechanical parts of the turbine are the casiiig, the
steel retaining rings enclosing the wheels, the wheels mounted on the shaft,
the diaphragms separating the several stages, the bearings supporting the
shaft at both ends of the casing, the adjusting block which controls the position
of the wheels relative to the nozzles, the moving blades mounted on the wheels,
the nozzles which are built as a part of the diaphragms, the shaft glands, the
bushings attached to the diaphragms to prevent steam leakage from stage to
stage around the shaft, and the governor for regulating steam admission to
the steam chest.

FIGURE 126.

De Laval Pressure Compoimded Turbine.

The rotor is built up of a niunber of wheels mounted on a shaft, one wheel
for each pressure stage. The wheels are attached to the shaft, as shown in
FIGURE 126. Tapered sleeves are fitted and keyed to the shaft against a
shoulder on the shaft. The wheels are then forced on the sleeve by means of
a nut, and are held from rotating on the shaft by keys.

FIGURE 126 also shows the method of steam packing the diaphragms
around the shaft by means of steel bushings in which are fitted packing rings.

Each pressure stage consists of a row of stationary nozzles through which
steam is expanded, and a row of moving blades attached to a wheel. The

AUXILIARY MACHINERY. 167

d by two diaphragms and the retaining ring,
initial pressure tu exhaust pressure in steps,
set of nozzles. The pressure drop from one
pounds. The nozzles employed for the first
;he eireumferenee in order to a^"oid the diffi-
is in the first pressure stage. Any or all of
y hand operated valves seating upon the inlet
valves is to permit of the admission of more
)s greatly at different periods. Governing is
;eam admission to the steam ehest.

FIGURE 127.

Section Through Blading and
Nozzles.

and retaining rings are shown in section in
but the first stage are formed between guide
lery of the diaphragm. The vanes are spared
diaphragm by pins, and are held in plaee by
ir tips. Two pins are used for each vane to
? nozzles are the spaces thus formed between
wider than the vanes and diaphragms, and.
ce, these bands form the retaining rings for

168 STEAM TUBBIXES.

the iseveral stages. FIGURE 128 shows a complete diaphiagm with vanes and
retaioisg rings se^rured in plarre.

The shaft gland packing for De L^val turbines is shown in c-ross-sectim
in FIGURE 129. The carbon segments are held against the shaft by spiial
rintpi, and are held in plaf::e longitudinally by springs at the side. ProvisloD
is made for intr^Klu'ring live steam at reduced pressure between the second
and third rings, so that any leakage into the turbine will be of steani. not air.
At the H- P. end, steam leakage from the first pressure stage is prevented bjr
labiTinth packing, but such leakage as takes place is into a chamber formed

FIGURE 128. FIGURE 129.

Conipleto Diaphi-agin nf De Laval De Laval Shaft Gland.

Pressure C'ompoiinfled Turbine.

hy the f-asing and is led to a stage of lower pressure. Carbon packing is iStted
at the H. P. end, as shown in FIGURE 125.

De Laval Blading. The blades f(jr the De Laval turbines are formed by
drop forging, and the bulb and shanks are accurately machined. Blades of
various sizes are shown in FIGURE 130. The method of securing the blades
to the wlieel is shown in FIGURE 131. The tips of the blades have projections
or higs whifrh fit against similar higs on the adjacent blades, forming a con-
tinuous rim. The blades are secured to the rim of the wheel by transverse
dovetails.

TUEBINES FOB AUXILIARY MACHINERY.

FIGURE 130.

De Laval Blades.

BMm

FIGURE 131.

Method of Securing De Laval Blades.

STEAM TURBINES.

KERR TURBINES.

Preuure Compounded Turbine. This turbine is manufaoturcd by the
Kerr Turbine Company. It is shown in cross-section in FIGURE 132. The
principle used is pressure (.-onipounding. Its essential mechanical parts are
the same as those of the Do La^'al pressure compounded turbine. The details
of construction are, however, different in several pai-ticulars.

The nozzles are formed by walls within the diaphragm, and their vanes
are die pressed into shape and cast into the diaphragm.

The rotor is made up of wheels secured to a shaft, as shown in FIGURE
133.

FIGURE 132.

Kerr Uressure C'unipounded Turbine.

The casing consists of steam and exhaust ends, between which are secured
the circular diaphragms which contain the nozzles and divide the casing into
separate stages. The outer rims of the diaphragms are brought together, and
when all assembled form, with the ends of the casing, the complete easing.
The diaphragms and ends of tlie easing are secured by through bolts. Tlie
casing is divided through the center line by a horizontal plane, so that the
top half of casing ends and diaphragms may be lifted as a whole to inspect
the i*otor, moving blades, etc.

Tlie prini'iple of pressure compounding is illustrated in FIGURE 134,
which shows the flow of steam through the Kerr turbine. The blading in the
plan view is cut away and the diaphragms are removed sufficiently to show
this steam action.

Blading is shaped and secured to the wheels by the same method as used
for the I)e Laval turbine.

TURBINES FOR AUXILIARY MACHINERY. 171

FIGURE 133. FIGURE 134.

Method of Securing Section Throngh Blading and NozzUs

Wheels. Sliowing Path of Steam.

172 STEAM TURBINES.

Part III.
GENERAL ELECTRIC TURBINES.

Velocity Compounded Single Stage Turbine. This turbine is manu-
factured by the General Electric Company. It is a Curtis turbine with one
pressure stage velocity compounded three times. FIGURE 135 shows the
cross-section of this turbine connected to a 5-K^^'". generator. FIGURE 136
shows the cross-section of a turbine for a 25-KW. generator. The mechanical
parts are the casing, two rows of guide blades attached to a segment secured
to the inner surface of the casing, the nozzles in segment form secured to the
casing head, the wheel to which is attached three rows of moving blades, and
shaft glands around the shaft where it passes througli the casing heads.

The path of the steam through the nozzles, two rows of moving blades,
and one row of guide blades is shown in FIGURE 137. Tlie steam is expanded

FIGURE 137.

Path of Steam Flow Through Moving

and Stationary Buckets.

Nozzle. Revolving. Stationary. Revolving.

in the nozzles, acquiring velocity during the expansion, is discharged against
the first row of moving blades attached to the wheel, and is reversed in direc-
tion. It then discharges into the guide buckets which again reverse the direc-
tion of flow and discharge the steam against the second row of moving blades.
The action through any pair of moving and guide blade rows is similar. The
steam finally flows from the third ro\^■ of moving blades to the exhaust. The
velocity of the steam increases through the nozzles and gradual!;^ decreases
through the moving buckets, remaining practically constant through the guide
buckets. The pressure within the compartment in which the wheel revolves
is praeticall}' constant at all points and is equal to the pressure at the exit end
of the nozzles, the pressure drop for the stage taking place in the nozzles.

J^SX.

TUBBINES FOE AUXILIARY MACHINERY. 173

FIGURE 136.

General Electric Curtis Turbine.

FIGIJRE 136.

General Electric Curtis Turbine.

174 STEAM TURBINES.

Two Stage Velocity Compounded Turbine. This turbine is manufac-
tured by the General Electric Company. It is a Curtis turbine with two pres-
sure stages, each velocity compounded three times. The action of the steam
in each pressure stage is the same as described above for one stage. FIGURE
138 shows the cross-section of a turbine for a 300-KW. generator.

FIGURE 138.

General Electinc Curtis Turbine.

FIGURE 139.

General Electric Curtis Turbine.

FIGURE 138a shows the passage of steam through a two pressure stage
General Electric Curtis turbine, in which each stage is velocity compounded
twice. The action of the steam through each pressure stage is the same as
descj'ibed above for the single pi-essure stage of the turbines shown in
FIGURES 13S and 136.

TUEBINES FOR AUXILIARY MACHINERY. 175

Preuure Velocity Compounded Turbine. This turbine is manufactured
by the General Electric Company. It is a Curtis turbine with three pressure
stages. The first pressure stage is velocity compounded twice. FIGURE 139
shows the cross-section of this turbine connected through reduction gear to a
300-KW. generator. The mechanical parts are the casing, guide blades
secured to the inner surface of the casing, nozzles for the first stage in segment

CLLVATKNt

FIGURE 138a.

form secured to the casing head, nozzles for the second pressui'e stage secured
to the first diaphragm, nozzle for the third pressure stage cast as a part of the
second diaphragm, diaphragms between the first and second and between the
second and third pressure stages with bushings surrounding the shaft to pre-
vent steam leakage from one pressure stage to the next, wheels upon which

176 STEAM TURBINES.

are secured the moving blades, and shaft glands around the shaft where it
goes through the casing heads.

The diagrammatic arrangement of nozzles and moving and stationary
blades is shown in FIGURE 140. The steam enters at A from the st«am pipe,
passes into the steam chest B, and then through one or more open valves to the
bowls C The number of valves open depends on the load, and their action is
controlled by the governor. Prom the bowls C, the steam expands through
divergent nozzles D, entering the first row of revolving buckets of the first
stage at E, thence passing through the stationary buckets G which reverse its
direction and discharge it against the second row of revolving buckets H. This
constitutes the performance of the steam in the first stage, or pressure cham-

FIGURE 140.

Diagrammatic Arrangement of Moving and Stationary Elements
of Curtis Turbine Shown in Figure 139.

ber. Having entered the first row of buckets at E with relatively high velocity,
the steam leaves the last row H with a relatively low velocity, its energy
between the limits of inlet and discharge pressure having been abstracted in
passing from C to H. It has, however, a large amount of unexpended energy,
since the expansion from C to E has covered only a part of the available pres-
sure range. The expansion process is, therefore, repeated in a second stage.
The steam having left the buckets H, and having had its velocity greatly
reduced, reaches a second series of bowls J, opening upon a second series of
nozzles K. Through these the steam expands again from the first stage pres-
sure to some lower pressure, again acquiring relatively high velocity in its
expansion through these nozzles, leaving them at L and impinging upon and
passing through the moving buckets M. This process is repeated in the third
stage nozzles N, and so on through the remaining stages, if any.

TURBINES FOR AUXILIARY MACHINERY. 177

The nozzle segment or plate for the first pressure stage is shown in
FIGURE 141. This shows the exit side of the nozzles with the holt holes foi-
securing the segment to the easing head.

FIGURE 141.

First Ktage H. F. Xozzle Flate for Cm-tis Steam Turbine
Showing Exit Side of Nozzles.

FIGURE 142.

Diagrammatic Arrangement of Curtis Turl)ine AVlieel Shiiwing
Buckets of a Single Curtis Typical Method of Attaching

Stage. Buckets and Shi-oud Rings.

Blading. The roots of the blading are dovetailed and secured in a grcHive,
as sliown in FIGURE 142. The blades are inserted in the slot A. The shroud-
ing B is then secured over the tenons at the tips of the bhule.s and tlie tenons
are riveted. Tlie form of ))I;uling is shown in FIGURE 143.

STEAM TURBINES.

5 i« « t

fif 611

FIGURE 143.

Gent'i-al Eloctric Curtis Blading.

Part IV.
WESTINGHOUSE TURBINES.

Combined Turbine. This turbine is manufactured by the Westinghouse
llacliine Couipiiny. It is of the combined type with an impulse wheel followed
by six reat-tion expansions. The impulse wheel is one pressure stage velocity
compounded twice. Steam admission covers only a part of the periphery.

The turbine is shown in FIGURE 144. The mechanical parts are the
rotor upon which the impulse and reaction moving blades are mounted, the
casing, the shaft which is a part of the rotor, bearings supporting the shaft
and rotor, a small adjusting block, dmnmy packing on the right end of the
rotor to i>i'e\"eiit steam leakage from the compartment in which the impulse
wheel revolves, nozzles Imilt in segments and secured to the right casing head,
impulse guide l)lades secured to segments which in turn are secured to the
easing, and reaction guide blades secured to the inner siirfaco of the casing.

TURBINES FOR AUXILIARY MACHINERY. 179

The steam is expanded in the nozzles and attains a high veloeity. The
velocity of the steam is extracted by two rows of moving impulse blades
secured to the impulse wheel. The steam exhausts from the seeond row of
impulse blades and passes through the reaction buckets with gradual reduc-
tion of pressure until it exhausts from the last row of reaction blades. The
steam tlien flows to tint condenser.

Tlie type of turbine shown in FIGURE 144 is used for driving a 300-KW.
irenerator on some of the latest battleships.

Velocity Compounded Single Pressure Stage Turbine. This turbine is
manufactured by the Westinghouse Machine Company. It is an impulse tur-

FIGURE 146.

Westinghouse Imi>ulse Turbine.

bine. The rotor consists of one wheel mounted uiwn a shaft supported by
l>earings, as shown in FIGURE 145. There is only one row of moving blades
on the wheel 1. The expansion of the steam takes place in a nozzle 2 from
entrance pressure to exhaust pressure. Upon discharging from the nozzle,
the steam passes through the wheel buckets 3, turning the wheel due to the
impulse of the steam upon the moving blades. After passing through the
buckets, the steam exhausts into a reverse chamber 4 in which the direction is
changed so that the steam may again be discharged against the moving blades.

180 STEAM TURBINES.

The steam action is shown in FIGURE 146. The velocity acquired by the
steam due to its expansion in the nozzle is extracted by the row of moving
blades in two steps. The first step is from the nozzle to the reversing chamber,
and the second is from the reverse chamber to the exhaust. The turbine is
thus velocity compounded twice, and is equivalent to two rows of moving

FIGURE 146.

blades on one wheel with a row of guide or stationary blades in between. A
view of the nozzle, re\'ei'8ing chamber, and rotor is shown in FIGURE 147.
The casing is removed.

FIGURE 147.

Pressure Velocity Compounded Turbine. The same method of using
revei-siug chambei-s is aj)pIiod to pressure velocity compounding. Two or more
pressm-c stages are used, each velocity compounded twice. One row of moving
lilades mounted on a wheel extracts the velocity acipiired by tlie steam in the
two pressure dii)ps of the nozzles of the two stisgcs.

TURBINES FOR AUXILIARY MACHINERY. 181

The action of the steam is shown in FIGURE 148. The first pressure
stage consists of a nozzle for expanding the steam and a revei-sing chamber.
The steam is discharged from the nozzles against the moving hlades, imparting
motion to them. It exhausts fi-om the wheel buckets into the first reversing
chamber where its direction is changed. The steam is then again discharged
against the moving blades. The velocity atrquired by the steam is thus extracted
in two steps in the first pressure stage. After leaving the wheel buckets the
second time, the steam discharges into a chest attached to the second nozzle.

FIGURE 148.

The second pressure stage consists of a nozzle for expanding the steam
to exhaust pressure and a reversing chamber. The action of the steam is the
same as in the first pressure stage, except that the steam, when it finally leaves
the wheel buckets, flows to tlie exhaust. The velocity acquired by the steam in
its expansion in the second nozzle is thus extracted in two steps.

The turbine is the equivalent of two pressure stages, each with a wheel of
two rows of moving blades with a row of guide blades between the two rows
of moving blades. The turbine is thus pressure staged twice, and each pres-
sure stage is velocity compounded twice.

182 STEAM TURBINES.

Part V.

KTURTEVANT TURBINES.

Sturtevant Velocity Compounded Single Stage Turbine. Tliis turbine is
maimfactun'd I)y the B. E. Sturtevant Company in nnits of various sizes.
It is an impulse turbine. The ]-otor consists of shaft, wheel, and blading
machined in the rim of the wheel. The wheel witli buckets is shown in
FIGURE 149. This tigm-c shows also the shape of the buckets. The buckets

FIGURE 149.

Rotor of Sturtevant Turliine.

are semicin-ular in foj-m and reverse the direction of the steam, driving the
steam back into a set of stationary or reverse Imckets of similar design.

This turbine is shown in cross-section in FIGURE ISO. The nozzles are
bolted to the end of the casing and are arranged for individual steam control
by valves operated from the outside of the casing. The nozzle and guide blades
are milled from one piece, as shown in FIGURE ISl.

TURBINES FOR AUXILIARY MACHINERY. 183

Steam is expanded to exhaust pressure in the nozzles and attains a high
velocity upon exit from the nozzles. It impinges against the blades of the
rotoj-, is reversed by them in direction, and is then discharged into the first guide
bucket. This guide bucket reverses the steam to its original direction and
discharges it against the next bucket. This process continues until the steam

FIGURE 150.

Sturtevant Tui-bine.

FIGURE 161.

Sturtevant Nozzle and Reversing Block.

finally discharges fi-om moving buckets clear of the last guide bucket. The
effect is a reduction of velocity of the steam as the steam flows from nozzle
exit to the chamber surrounding tlie rotor. Velocity is extracted by the rotor
at each passage through a moving and fixed bucket. The nozzle and guide
buckets shown in FIGURE ISl would be the equivalent of one pressure stage
velocity compounded five times.

184

STEAM TURBINES.

Part VI.
TERRY TURBINES.

Terry Velocity Compounded Single Stage Turbine. This tiirbiiK' is iiia]iu-
factured by the Terry Steam Tiirl>iiu' Company. It is an impulse turbine.
Tlie rotor and buckets are similar to those of the Stnrtevant turbiue, but the
method of securing the nozzles and guide buckets diffei-s slightly. The nozzle
is attached to the head of tlie casing, and the reversing chamber is attached to
flanges projecting inward from the casiiig.

The principle of operation is shown in FIGURE 152. Steam is brought
to the nozzle under control of the governor and is expanded through the nozzle

FIGURE 152.

Terry Nozzle and Reversing

FIGURE 153.

Tei'i-y Velocity Compomided Pressiii-e
Staged Turbine.

which directs the steam into the Inicket near the side of the wheel. The
moving buckets change the direction of flow of the steam. Guide buckets are
used to redirect the steam against succeeding liuckets, as in the Sturtevant
turl)inc.

The Terry Steam Turbine Company also manufactures a turl)ine with one
velocity wheel as described above, followed by several jjressure stages, each
with onlv one row of moving blades. A cross-section of this turbine is shown
in FIGURE 153.

CHAPTER XV.

LUBRICATION.

Theory. The theory of lubrication is that a fihn of oil is interposed
between the journal and bearing, completely separating the two. The friction
is then reduced from that due to a solid rubbing on a solid to the friction of
the lubricating substance. By the separation of the journal from the bearing,
friction between the two is practically eliminated, and wear and abrasion are
reduced to a minimum. The absence of wear and abrasion means a reduction
of heat generated in the bearing and the elimination of ** hot bearings. '^ In a
bearing that is heated, due to an insufficient supply of lubricant, the journal
will tear the surface of the bearing and heating may be so rapid as to melt
the anti-friction metal with which the bearing is lined.

Requirements. To obtain proper lubrication, the following requirements
are necessary:

1. The use of a high-grade lubricant.

2. The lubricant must be free from grit, acid, and other foreign
substances.

3. The supply of lubricant must be abundant at all times.

4. The introduction of the lubricant to the bearing surfaces must be
at the point of lowest pressure.

5. The bearing must be of slightly greater diameter than that of the
journal, to allow the journal to carry the lubricant between the rubbing
surfaces.

6. Bearings must be properly aligned and carefully fitted.

Lubricant Used. The lubricant used for turbine bearings in the U. S.
Navy is a high-grade pure mineral oil free from grit, water, and acid.
Mineral oil is used because it can be readily separated from water, filtered,
and used over again. An oil containing vegetable or animal oil saponifies
when mixed with water or steam and cannot for this reason be used more
than once.

Turbine Lubrication. For steam turbines, it is absolutely essential that
the bearings be properly lubricated to reduce wear of the bearings and to
insure that the turbines may be depended upon when running. Reliability of
operation for the propelling machinery is an absolute necessity on a man-of-
war to insure that it maintain its place on the firing-line. Reduction in wear
of bearings means a reduction in the cost of overhaul and a reduction in time
taken to adjust clearances in those turbines where tip clearance is an important
matter. The rapid wear of bearings will cause the rotor to settle with an
increase of tip clearance at the top of the turbine and a decrease in tip clear-
ance at the bottom of the turbine. The heating and melting of bearings while
the turbine is running may cause the tips of the blades to touch the casing to
such an extent as to cause stripping of the blades.

186

186 STEAM TURBINES.

Forced Lubricatioii. To insure reliability of running, forced lubrication
is used on marine turbines. The oil is supplied to all bearings under a pres-
sure of from five to ten pounds per square inch at the bearings by pumps
installed for the purpose. The bearings are closed as completely as possible
to prevent loss of oil, and each bearing is provided with a chamber beneath
the bearing into which the oil may drain after being used. Prom the drain
chambers of all bearings closed drains are led to a drain tank which collects
the oil for further use.

Forced lubrication is used for all bearings and thrust bearings of the pro-
pelling turbines, for gear bearings, gear teeth, and the bearings of main
circulating pumps.

For the ordinary type of cylindrical bearing, the oil is led through the
bearing at several points to the space between the journal and the bearing
surface and distributed by suitably cut oil grooves in the bearing surface, in
order that it will come in contact with the entire length of the journal surface.
The journal, by virtue of its revolving motion and of the adhesion of the oil
to its surface, will carry the oil around with it and maintain the oil film as
long as the supply of oil is abundant. The oil will run out of the off-side of
the bearing and from the ends of the bearing. To prevent oil from flowing
through the bearing casing and into the turbine, oil guards are fitted to the
beai'ings. The Parsons type of guard as fitted on the ARIZONA is shown in
FIGURE 154. The Curtis type of guard as fitted on the NEVADA is shown
in FIGURE 155. The tendency of the oil to flow to the parts of the shaft of
greatest diameter is taken advantage of to prevent the oil from creeping along
the shaft. When enough oil collects on the surface or edge of greatest diameter,
due to centrifugal action, its weight causes the centrifugal force to become
great enough to overcome the adhesion of the oil to the shaft and the oil is
released from the shaft and discharged against the inner surface of the bear-
ing casing from which it drains to the chamber beneath the bearing.

The supply pipe to a bearing may be fitted with a sight feed glass and a
pet cock, in order that frequent inspections may be made to insure that the
bearing is getting its proper supply of oil. Thermometers are fitted to large
bearings to keep the engine-room watch informed as to the temperature of oil
discharge from the bearings while the turbines are nmning. Pressure gages
are sometimes fitted on the oil supply pipes, but are not as reliable for testing
for oil supply as sight feed glasses.

SURE 1S6.

I^uards — ^N evada.

LUBRICATION. 189

Thrust bearings of the Pai-sons type and of the horse-slioe type are hibri-
cated by forcing the oil through the thrust blocks to the inner edge of tlie
bearing surface, as shown in FIGURE 156. The oil discharges into the space

FIGURE 166.

Oil Supply to Thrust Bearing.

between the thrust block and the thrust collar. It is carried around with the
thrust collar and works towards the outer edge of the thrust collar. From
this edge it is thi'own against the thrust bearing casing and flows to the drain
chamber beneath the bearing.

190 STEAM TURBINES.

Small sized cylindrical bearings (iii turbines for auxiliary machinery may
be lubricated with ring lubrication. This system is illustrated in FIGURE 157.
Beneath the bearing is an oil resei-voir. A ring larger in diameter than the
diameter of the journal is hung on the top of the journal and pressed against
the journal by means of a spring. This ring revolves with the jouraal and
through the oil in the reservoir. It picks up the oil and carries it to the top
of the journal where it is wiped or scraped off the ring by a stationary wi])er.
It then flows by suitable grooves to the journal surface and is carried in
between the journal and bearing. After being used on the bearing sui'faees,
the oil flows to the reservoir.

The lubrication of gear teeth is accomplished by spraying the oil on the
teeth just before the teeth come in contact with each other. Several sprays
or nozzles are used for large gear-wheels. The oil nozzles used on the

FIGURE 157.

Ring Lubrication.

WADSWORTH'S gears is shown in FIGURE 158. Each nozzle may be
removed independently for inspection for clogging by closing the oil valve
on tlie casing, coming up on the screw of the yoke, and turning the yoke to
one side. The nozzle 2 may be removed and the nozzle tip 3 may be unscrewed
and inspected.

NEVADA'S System (FIGURE 159). The NEVADA'S forced lubrication
system is a type installation for large ships. For each of the poi-t and star-
board turbine installations is a 1000-gallon storage tank, a 250-gallon drain
tank, a 275-gallon settUng tank, an oil cooler, and two oil pumps. The pumps
are installed so that both pumps can pcrfonn the same functions, and the
lubrication system is cross-connected through the center-line bulkhead to allow
the pumps in either room to draw oil from or discharge oil to tlie settling tanks
in both engine-rooms.

Each storage tank has a pipe to the deck for filling. Oil flows from the
storage tank by gravity to the suction of one of the pumps until the system is
filled to capacity. This method is used to supply additional or new oil to the
system at any time. The pump suction also receives oil from the settling
tank while the system is in operation. It discharges this oil through the oil

FIGURE 168.

Oil Nozzle for Gearing.

Gear Casing

LUBRICATION. 191

cooler to the bearings and gearing through branch pipes. The oil drains from
the bearings and gearing to the drain chambers beneath them, and then
through drain pipes to the drain tank.

The other pump takes oil from the drain tank and discharges it to the
settling tank. In the settling tank, the sediment falls to the bottom of the tank
and the water and oil are allowed to separate. Water enters the bearings and
gets mixed with the oil from the shaft glands and from any leakage from the
salt water circulating through the bearing caps. To separate the oil and water,
a steam coil is installed in the settling tank, and one may be installed in the
drain tank. In order to obtain a rapid settling out of the water, the oil from
the bearings may be heated for a considerable period at a temperature as
high as 200°F. without material harm to the oil. The presence of water in oil
in contact with a bearing and journal is harmful under any conditions. Its
presence will increase friction, reduce the ability of the oil to form and main-
tain the oil film, and corrode the journals.

A simple method of testing oil for water is to draw into a test tube a small
quantity of the oil to be tested. Mix with this sample an equal quantity of
gasolene. Shake the mixture thoroughly and allow to stand. The water will
settle to the bottom of the test tube. If a graduated tube is used, and the
amount of the sample and the amount of the gasolene measured, the amount
of water may be measured and the percentage of water in the oil readily
determined.

The oil is reduced in temperature in the cooler by circulating salt water
through a coil in the cooler. This water is supplied by an oil cooler circulating
pump on each side of the ship.

The functions of the two oil pumps may be siunmarized as follows when
the system is in use:

Suction. Discbarge.

Pump A. . . .From storage tank Through cooler to bearings.

From starboard or port set- Direct to bearings (cooler is by-
tling tank. passed ) .

Pump B . . . .From drain tank To starboard or port settling

tank.

There is a drain from the. oil settling tank to the bilge for draining off
water from this tank. The height of the water is indicated in a gage glass
attached to the settling tank. A drain leads from the bottom of the storage
tank to a drip-pan for supplying oil for oil-cans for hand oiling of such
machinery as is not fitted with forced lubrication.

Oil may be taken by either pump from the drain tank and discharged
through the cooler to the bearings and gearing.

The supply pipes to bearings and gearing and the pimip suctions are
fitted with strainers to prevent any solid matter being carried by the oil to
the bearings.

The drain tank is installed sufficiently below the turbines to allow oil to
run freely from all bearings and the gear box to the drain tank.

192 STEAM TURBINES.

CONYNGHAM'S System (FIGURE 160). The CONYNGHAM'S forced
lubrication system is a type installation for destroyers. There is one 500-gallon
storage tank, one 50-gallon storage tank, one 200-gallon drain tank, two 200-
gallon settling tanks, an oil cooler, and two oil pumps. The circulation of oil
for the entire tiu^bine installation is accomplished by the two pumps. The
pumps are installed. so that both pumps can perform the same functions.

Each storage tank has a pipe running to the deck for filling. Oil flows
from the large storage tank by gravity to the suction common to both pumj^s.
This method is used to supply additional or new oil to the system at any time.
Both pumps have a common suction from the drain tank, a common discharge
to the settling tanks, and a common discharge through the cooler to the bear-
ings and gearing.

With one pump in operation, oil is taken by the pump from the drain
tank and discharged through the cooler to the bearings and gearing. The oil,
after running from the bearings and gearing, drains to the drain chambei's
beneath them and then through drain pipes to the drain tank.

Whenever the oil becomes thick it mav be removed from the svstem bv
the second pmnp and discharged to one of the settling tanks. When not imder
way, the drain tank may be emptied by either pump and the oil discharged
to one of the settling tanks. Great care must be exercised to prevent the
drain-tank suction of the pimip operating on the bearings from becoming
uncovered. When oil is removed from the system to one settling tank, new
oil may be supplied from the storage tank, or the oil in the second settling tank
may be run by gravity to the drain tank. Or, w^hen under way, oil may be
pumped by both pumps from the drain tank, the after pump discharging
through the cooler to the bearings and gearing and the forward pump dis-
charging to one of the settling tanks. In this case the bottom drain from the
settling tank is closed and the overflow pipe from the settling tank to the
drain tank opened. Thick oil will go to the bottom of the settling tank and
the thinner oil will flow to the drain tank from the top of the settling tank
through the settling tank overflow pipe.

There is a drain from each of the settling tanks and from the drain tank
to the bilge for draining ofi^ water from these tanks. The height of water is
indicated by gage glasses attached to the tanks. A drain leads from the bottom
of the 50-gallon storage tank to a drip-pan for supplying oil for oil-cans for
hand oiling of such machinery as is not fitted with forced lubrication.

The supply pipes to bearings and gearing and the pump suctions are
fitted wdth strainers to prevent any solid matter being carried by the oil to the
bearings.

The drain tank is installed sufficientlv below the turbines to allow oil to
run freely from all bearings and gear box to the drain tank.

d Turbine

FIGURE 160.

Plan of Forced Lubrication-
Oonyngham.

V9nks

rain from Bearl

Settling Tanks

CHAPTER XVI.

INSTRUCTIONS FOR THE CARE AND OPERATION OF PARSONS

TURBINES.'

The following instructions are issued with a view to aflfording assistance
to those in charge of turbine machinery of the Parsons marine type, and have
been compiled to cover two-, three-, and four-shaft arrangements and installa-
tions with or without cruising turbines:

Divisions under the following headings are given, viz. :

A. Forced Lubrication.

B. Warming Up.

C. Maneuvering.

D. Full Power.

E. Cruising.

F. Gland Arrangement.

G. Closing Down.
H. General.

I. Adjusting Turbines.

J. Opening Out Turbines for Inspection.

K. Gearing.
The letters H. P. refer to Main High-Pressiu'e Turbine.
The letters I. P. refer to Intermediate-Pressure Turbine.
The letters L. P. refer to Low-Pressure and Astern Turbine.
The letters H. P. A. refer to High-Pressure Astern Turbine.
The letters H. P. C. refer to High-Pressure Cruising Turbine.
The letters I. P. C. refer to Intermediate-Pressure Cruising Turbine.

A. FORCED LUBRICATION.

Before Opening Any Steam Connections to the Turbines:

1. The oil pumps must be started (all necessary cocks and valves
being opened) and the system examined to ensure that oil is flowing freely
through all turbine bearings and adjusting blocks (and also through all
plummer blocks or line-shaft bearings, where these are fitted with forced
lubrication).

2. The discharge at the oil piunps should be regulated so that a pres-
sure between five and ten pounds is obtained at the turbine bearings and
adjusting blocks. Pressure gages are usually provided in connection with
the bearings and adjusting blocks for this purpose.

Before Starting the Oil Pumps:

1. Ensure the absence of water in the oil drain tank by opening the
drain cock, or bv piunping from the bottom of the tank by the hand pump,
according to the provision made for this purpose.

Opportimity should be taken to occasionally repeat this opera-
tion, so that in the event of water collecting it may not be allowed to
accumulate beyond the height of the oil suction-pipe of the drain tank.

' The Paraons Marine Steam Turbine Company, Ltd., 97 Cedar Street, New York, N. T.

198

194 STEAM TURBINES.

2. Sound the oil drain tank to see that the supply of oil is sufiSeient
for the system, and after the system has been charged sound the tank
again to ensure that there is still suflRcient oil in the tank; when necessary,
replenish from the reserve tank.

3. Open by-pass valve to prevent oil flowing through cooler. (Diffi-
culty is experienced in forcing cold oil through coolers, when latter are
fitted with retarders.)

4. Try the sea water service pump (to cooler) imder steam.

After Starting Ofl Pumps:

1. Examine drain tank again and recharge from reserve tank if
necessary.

2. See that the above-mentioned oil pressure is maintained at the
bearings.

3. When oil temperature reaches about 90°P., close by-pass and dis-
charge oil through coolers.

When Under Way:

1. Start sea water circulating pump to cooler.

2. Ensure that a pressure of about 10 pounds is maintained in the
oil system to bearings.

3. Test cocks or sight holes (as fitted) should be examined frequently
to ascertain that the oil is flowing freely through each bearing.

4. Thermometers are frequently fitted to the ** turbine bearings,"
and the temperature of the oil leaving the bearings and adjusting blocks
should be regularly noted.

5. The strainers should be frequently overhauled and cleaned out.

6. The quantity of oil in the drain tank should be noted at regular
periods, to ensure that there is no loss of oil through leakages.

After Steaming:

1. When the oil has settled, a quantity should be drawn from bottom
of the drain for examination and all oil which has become thick should
be removed.

2. Many turbines are built with oil drain wells at bearing ends and
it is advisable to regularly examine these wells and remove all dirt and
sediment.

B. WAEMING UP.

Before Turning on Steam to Warm Up the Turbines Ensure That:

1. Turning gear is withdrawn and secured out of gear.

2. All drain valves and cocks in connection with the tiu^bines are
open, except the air-piunp drain to bilge, which must be closed.

3. Self-closing valves between turbine cylinders are free to open.

4. All main, cruising, and maneuvering steam regulating valves are
closed.

5. An air-pump and a circulating piunp are working in connection
with each cylinder. Vacuum in condensers not to exceed five inches.

6. Where an oil cooler is fitted, the circulating water should be shut
off after being tried, so that, when warming up, the heat may not be
extracted from the cylinders by the cool oil circulating through the
bearings.

CARE AND OPERATION OF PARSONS TURBINES. 195

7. Ease off their faces the self-closing valves and regulating valves
necessary to allow steam to flow through the series of ahead and astern
turbines to the condensers. Turn steam on to the gland system and
thereby assist the heating of the ends of the turbines.

A special steam heating arrangement is sometimes provided in
large vessels, and the turbines may be heated up by these con-
nections (where fitted) instead of using the main regulating valves.
These connections are usually embodied in the turbine gland steam
arrangement.

In Large Installations:

After this has been carried on for one-half hour, shut off steam
and turn each rotor one-quarter of turn either way with jacking
gear or mechanical turning gear; then open steam valves again.
In another 15 minutes time, steam should be shut off and rotors again
turned one-quarter of turn. This method should be carried out imtil
rotors have completed three turns. This will occupy about three
hours, and by that time the turbines will be fairly well warmed.

The engineer in charge should now decide whether it is advisable
to try and start the turbines with their own steam or carry out the
warming-up process for another hour.

Care should be taken when rotors are being jacked over to soimd
the turbines and see if the rotors are moving freely. Another method
is to have in the first place plenty of steam on the gland system, then
allow a large voliune of low-pressure steam to flow into tiie tiu*bines
both ahead and astern, keep the vacuum very low and only sufficient
to keep the turbines clear of water and allow this to go on for three
hours, then shut off steam, jack over each turbine, and at same time
** soimd '' to see that rotor is running freely. If running freely, jack
over one-half turn and allow steam to flow for one-half hour. Finally,
jack over one-quarter turn every 10 minutes and allow vacuum to
increase to 15 inches, and try tiuming the turbines under their own
steam pressure alternately in ahead and astern directions.

8. Where slide, piston, or other types of maneuvering valves are
fitt^, for supplying steam to the L. P. and astern cylinders, the direction
of the flow of steam should be frequently reversed.

9. After the engineer in charge is satisfied that all the turbines are
sufficiently warmed, and the usual precautions have been taken to see
that all is clear, the rotors should be given a few turns ahead and astern
under steam as in the usual procedure with reciprocating engines.

10. In some vessels a small by-pass valve has been arranged in order
that, when running continuously ahead and maneuvering operations are
anticipated, the astern cylinders may be warmed up a little, thus relieving
these cyUnders of any racking expansion strains due to the sudden admis-
sion of high-pressure steam.

11. Open steam valve connections to all steam packed expansion joint
glands on pipes connected to turbines.

12. After warming-up is completed and when standing by, waiting for
orders, it is advisable to give the rotors a few turns every five minutes.

196 STEAM TURBINES.

C. MANEUVERING.

On Receqyt of Orders to Stand By for Leaving Anchorage, Etc:

1. See that all necessary auxiliaries (oil, air, and circulating pumps)
are working satisfactorily and at least 25 inches vacuum in condensers.

2. See that the ahead and astern maneuvering or regulating valves
are closed, or in mid-position (according to the type fitted), and that the
master valves (where fitted) which supply steam to them are full open.

3. Ensure that all self-closing valves (where fitted) between the tur-
bines are on their seats, and that all drain valves on the turbines, pipes,
and fittings are open and remain so during maneuvering operations.

4. When maneuvering it is a good plan to bring the rotors to rest
(after receipt of ** stop '' or telegraph) when moving in ahead direction
by admitting steam to the astern turbines. In this way the astern turbine
casings and rotors can be kept in warm condition.

D. MAIN TURBINES, OR FULL POWER.

Before changing from maneuvering to the main turbines, warm up the
H. P. turbine as follows (while the other turbines are being used for
maneuvering) :

1. Open drains on H. P. master and regulating valves and on all
pipes, etc., leading to the H. P. turbine.

2. Open H. P. master valve (if fitted) and ease off regulating valve
to admit warming steam.

To Change Over to Main Turbines:

3. Open ahead maneuvering valves to keep ship under way until
H. P. ahead turbine is warmed.

4. Continue warming H. P. turbine by increasing amount of warming
steam imtil five pounds pressure in the turbine is reached, which pressure
may then be raised by successive increments of five pounds until it reaches
that which obtains in the H. P. exhaust pipes when running full ahead,
i. e., that which will obtain in the L. P. turbine belt after the change is
completed.

(These operations should occupy at least 15 minutes.)

5. See that all self-closing valves in cruising exhaust pipes are closed
and that those in H. P. exhaust pipe are free to open.

6. The change over can now be made by closing maneuvering valve
until the pressure at L. P. turbines is reduced to that in H. P. exhaust
and then gradually opening H. P. regulating valve and simultaneously
closing maneuvering valve until the latter is completely closed. The pres-
sure in the L. P. turbine steam belt should be kept constant during the
change over.

7. See that self-closing valves in H. P. exhaust pipes (if fitted) have
opened.

8. After a little time to drain off water from cylinders has been
allowed, close down drains on the running turbines.

9. Leave open drains on all driven turbines, such as cruising and
astern, and special attention should be paid to read pressure gages of all
turbines running idle in vacuum.

CARE AND OPERATION OF PARSONS TURBINES. 197

E. CRUISING.

1. Main to Cruising Turbine (Where One Cruising Turbine is Fitted).

Before making this change, the cruising turbine should be warmed for at least
15 minutes before it is brought into operation. During this time the admission
of warming steam should be gradually increased, the warming may be carried
on before steam to main turbines is shut off, as follows:

(a) Reduce pressure at H. P. turbine to that obtaining in cruising
turbine exhaust pipe when rimning imder cruising conditions, i. e., that
which will obtain at the H. P. turbine steam belt after the change over.

(b) Open drains on cruising master or regulating valve and all pipes,
etc., connected to the cruising tm^bine.

(d) Open cruising master valve (if fitted) and ease off regulating
valve to admit a slight amount of warming steam which should be gradu-
ally increased until five poimds pressure is obtained in the cruising tur-
bine. This pressure should then be increased by successive increments
of five pounds imtil it reaches that of the H. P. turbine.

(These warming operations should occupy not less than 15 minutes.)

(e) The change over can now be made by gradually opening cruising
regulating valve and simultaneously closing H. P. valve.

(f) Ensure that self-closing valve in cruising exhaust pipe has
opened.

(g) Close down H. P. master valve.

(h) After allowing time to drain off all water in the cruising system,
close drains on cylinders, valves, pipes, etc.

2. Main to H. P. C Turbine (Where an 1. P. C. Turbine is Also Fitted) :

(a) Reduce pressure at H. P. turbine to that obtaining in I. P. C.
turbine exhaust pipes when running with steam on H. P. C. turbine, t. e.,
that which will obtain at the H. P. turbine steam belt after the change
over.

(b) Open drains on H. P. C. master or regulating valves and all
pipes, etc., connected to the H. P. C. turbine.

(d) Open H. P. C. master valve (if fitted) and ease off H. P. C.
regulating valve to admit a slight amount of warming steam to H. P. C.
and I. P. C. turbines. This amoimt should be graduaUy increased until
five pounds pressure is obtained in the cruising turbines, after which it
should be increased by successive increments of five poimds until it reaches
that of the H. P. turbine.

(These warming operations should occupy not less than 15 minutes.)

(e) If cruising turbine regulator valves are fitted with by-passes,
then warming up can be carried out by opening them in place of the
regulator valves.

(f ) The change over can now be made by gradually opening H. P. C.
regulating valve and simultaneously closing H. P. valve.

198 STEAM TURBINES.

(g) Ensure that self-closing valves in H. P. G. and I. P. C. exhaust
pipes have opened.

(h) Close down H. P. master valve.

(i) After allowing time to drain off aU water in the cruising system,
close drains on H. P. C. and I. P. C. cylinders, valves, pipes, etc

3. Main to L P. C Turbine (Directly). Proceed as in clause 1 for a
single cruising turbine, taking care that:

(a) The self-closing valve in the H. P. C. turbine exhaust pipe is
dosed.

(b) H. P. C. cylinder drain is left open (see D, paragraph 9).

4. L P. C to H. P. C Proceed as in clause 1 treating the H. P. C. and

I. P. C. turbines of this case respectively in the same manner as the cruising
and H. P. turbines in clause 1.

5. R P. C to L P. C. :

(a) Open H. P. C. cylinder drain (see D, paragraph 9).

(b) Close down H. P. C. regulating valve gradually, simultaneously
opening I. P. C. regulating valve until the change over is completed.

6. Cruising to Main:

(a) Open aU cruising cylinder drains (see D, paragraph 9).

(b) Close down cruising regulating valve gradually, simultaneously
opening H. P. regulating valve until the change over is completed.

7. Main or Cruising to Maneuvering (When Maneuvering is Anticipated) :

(a) Excepting cases of emergency, warm up the astern turbines and
I pipe connections for at least 15 minutes before bringing them into opera-
' tion, gradually increasing the admission of warming steam without appre-
; ciably decreasing the revolutions of the ahead rotors.

(b) Open drain valves on all turbines, fittings, pipes, etc. (These
should be left open during maneuvering operations.)

P. TURBINE GLAND ARRANGEMENT.

When Getting Under Way:

j 1. The air and circulating pumps having been started, and, conse-

[ quently, a vacuiun formed in the condensers and throughout the turbines,

: steam must be supplied to the glands of all turbines. Then, as the steam

I supply to the turbines is gradually increased, the steam supply to the

glands will require reducing or increasing to suit the internal pressure
I above or below atmosphere at which the various turbines are exhausting,

and the gland leak-off connections opened and regulated as required.

Principle of the Turbine Glands:

1. The glands on the turbines are steam packed and are designed to

obtain a gradual fall or rise in pressure from the inner or steam end to

j the outer or atmospheric end of the gland, according to the internal pres-

CARE AND OPERATION OF PARSONS TURBINES. 199

sure obtaining at the inner end of the gland, which, being the exhaust
pressure of the turbine, may be above or below atmospheric pressure,
according to the conditions under which the turbine is working.

The gland rings and strips are arranged in groups, and the
spaces between the groups are connected to supply direct steam or
to pass gland leakages to such positions in the range of pressures
throughout the turbine installation that will give the pressure desired
between the series of strips and rings at any gland; i. e., when a
turbine is exhausting at pressure above atmosphere its gland con-
nections are to be regulated to give a gradual drop across the groups
from the exhaust pressure of the turbine to the atmosphere; when a
turbine is exhausting at pressures below atmosphere its gland con-
nections are to be regulated to give a gradual rue across the groups
from the exhaust pressure of turbine to the atmosphere. Valves are
fitted to the glands at each end of all turbines, and, in addition to
the direct steam supply, the connections to them are so arranged in
the turbine system that, if the valves are correctly manipulated, a
gradual rise or fall in pressure across the gland will be obtained,
according to the exhaust pressure of the turbine.

By the above arrangement any excess of pressure at the glands
is utilized to the best advantage, and any want of pressure is supplied
at the least expense of live steam. In order to reduce the wear of the
gland rings, due to side thrust, the pressure of steam at the gland
pocket next to these rings should be kept as low as possible consistent
with preventing leakage of air into the glands (which would tend
to impair the vacumn), and frequent observations should be made of
the pressure gages fitted for indicating the pressure in the gland
pockets.

It is necessary to have steam on all the glands of turbines which
are not in use, but of which the rotors are revolving in vacuum.

2. Another system which makes use of any excess steam leakage from
the glands and which uses auxiliary exhaust steam consists of the following :

One steam pipe runs through the engine-room from which
branches lead to all the gland boxes throughout the installation.
This pipe is connected to the auxiliary exhaust line to condensers
and to the turbines.

Under cruising conditions the leakage of steam from the glands
above atmospheric pressure is more than suflScient to pack the others
under vacuum and no auxiliary exhaust is used, and in addition it
may be necessary to pass an excess of steam either to turbines or to
condensers. On the other hand, when the leakage from the glands
under pressure is not sufficient to pack the remainder, then auxiliary
exhaust steam is used.

A pressure of 1 pound to 1.5 pounds should be maintained in the
steam pipe to glands.

200 STEAM TURBINES.

G. CLOSING DOWN TURBINES.

When Finished with the Turbines:

1. Special care must be taken to open all drains and keep the air-
pumps working for about two hours until the system has had time to be
thoroughly drained and dried, after which the air-pumps may be stopped
and the air-pump drain to bilge opened. Care must be taken that the
bilge water is not allowed to reach the height of this drain.

2. Drying valves are provided on some turbines, and when the air-
pumps have been stopped, these valves and all the valves provided on the
cylinder drain connections should be opened. A current of air through
the turbines will then be formed and will considerably help in drying out
the internal parts of the turbines.

3. There are various drain holes in the rotors, and the positions of
these holes are usually marked on the rotor couplings. One of these marks
should be turned to the bottom center and therebv permit of the rotor
being drained.

4. The turbine cylinders should be kept thoroughly drained in harbor.
All turbine rotors should be turned by hand each day and left about a
quarter of a revolution in advance of the position on the previous day.

5. Unless special attention is paid to making sure that the turbines
are thoroughly drained and dried out after shutting down, pitting and
corrosion will take place on the internal surfaces of the rotor.

Experience has shown that this can be largely overcome by dry-
ing out the installation thoroughly.

6. It has been found beneficial to start an oil piunp every second day
and force a fresh supply of oil through all bearings and adjusting block
collars. This keeps all journals free from rust and reduces pitting that
may take place while turbines are idle.

It is not advisable to do this if the oil has been in use a consider-
able length of time. It is a very good plan to remove bearing caps
or imscrew the pressure-gage connection on bearing caps and pour
fresh oil over the journals when the machinery is shut down for any
length of time.

7. When the vessel is to be in port for a week or two and the turbines
are allowed to cool off thoroughly, it is very advisable that the interior
of the turbine rotors be examined and for this purpose manholes are pro-
vided on the ends, on the receiver pipes, and on main exhaust bends to
condensers. Further, by opening up the manholes on receiver pipes and
exhaust bend, the condition of the last row of moving blades on rotors
can be noted.

Care should be taken to ensure that the engineers who make the
internal examination do not leave or lose any tools or personal belong-
ings inside the casings.

CARE AND OPERATION OF PARSONS TURBINES. 201

H. GENERAL.

Auxiliary Exhaust Connections to Turbines:

1. Provision is frequently made in the auxiliary exhaust system to
allow the surplus auxiliary exhaust steam to be utilized in the turbines.
These connections are so arranged that the exhaust steam may be directed
to various positions in the turbines, or their connections, according to
the pressure which is being maintained at such stages, when the turbines
are working. The arrangement of these connections may differ in the
various vessels, but the principle upon which they are worked is the same,
viz.: spring-loaded or back-pressure valves are fitted at the condensers,
and may be regulated to give sufficient back-pressure in the exhaust system
necessary to cause the exhaust steam to flow into the turbine installation
through spring-loaded non-return valves, which are fitted to prevent steam
flowing into the exhaust range from the turbines and thereby creating a
greater pressure in the exhaust pipes than permissible.

2. Steam from the auxiliary exhaust system, when admitted to the
turbines in the above manner, results in considerable economy, particularly
at low powers, and should be so used whenever practicable. Care, how-
ever, must be taken that on receiving orders to stop or go astern, or if
maneuvering is expected, the auxiliary exhaust system is to be immedi-
atdy shut off from the turbine receivers, and that there is free exhaust
to the condensers, or the rotors may be distorted due to unequal heating
and so cause damage to the blading.

Augmenter Condenser and Steam Jet In all installations fitted with the
Parsons vacuum augmenter it is advisable to note :

1. The water inlet and outlet valves on augmenter condensers or
pipe connections should always be left open, the cooling water being
usually supplied from the circulating water to main condenser.

2. The steam valve to augmenter jet to be opened only when the
machinery is under way.

Engine-Room Recorck. On the engine-room log sheet the following par-
ticulars regarding the turbine installation should be noted every hour:

1. Revolutions per minute for each shaft.

2. Steam pressure at steam belts of all turbines, including those run-
ning idle in vacumn.

3. Condenser vacuum.

4. Pressure of oil supply to bearings and temperatures of oil dis-
charge from all turbine bearings.

5. Amount of oil in oil drain tank.

6. The dummy clearance readings taken with micrometer.

7. Auxiliary exhaust to condensers or to turbines (as case may be).

8. Revolutions per minute of auxiliary engines and temperatures of
circulating pmnp water and air-pump discharge.

9. Feed temperatvu^e.

10. Circulating water in and out of condensers (temperature).

11. Barometer (every 24 hours).

204 STEAM TURBINES.

6. Method of ascertaining the dummy clearance by means of the
micrometer :

(a) Take out the locking pin, set the spindle Y to allow its inner
end to come into contact with the stop V, screw up the sleeve Z imtil
such contact takes place, and ensure (e. g., by the use of a fine feeler
gage between the collar of the sleeve and tiie collar of the spindle
at P) that the sleeve has not been screwed in too far or an inaccurate
reading will be obtained at the graduated rim of the handwheel. The
handwheel should then be set with the zero mark opposite the
index S.

(b) Draw the spindle back, turn it to allow its inner end to
come into contact with the dinnmy ring T, screw up the sleeve Z until
such contact takes place and test the joint at B as before. The read-
ing on the handwheel at the index S will indicate the dummy clear-
ance in thousandths of an inch. The spindle Y should be again tried
on the stop V, as in (a), to ensure that no appreciable wear has taken
place during contact with the dummy ring if the rotor was revolving
at that time. Screw the sleeve back until the locking pin can be
inserted through the spindle and lock the micrometer out of gear.

(Note. — When the micrometer is being used and the turbines are running,
care should be taken that the spindle Y is not allowed to come suddenly into
contact with the rotating dummy ring T, also that when such contact is made
the reading is quickly but accurately taken, so that the time of contact may
be reduced to a minimiun.)

7. When the vessel was handed over the various gagings were as
follows :

(a) Gagings at finger-pieces, with turbines thoroughly hot and
rotors drawn forward imtil cylinder and rotor dimimies were in
contact :

Main H. P. turbine.
L. P. turbine (port).
L. P. turbine (starboard).
H. P. cruising turbine.
I. P. cruising turbine.

(b) Gagings at finger-pieces mth turbines at rest, thoroughly
hot, rotors adjusted, and hard forward:

Main H. P. turbine.
L. P. turbine (port).
L. P. turbine (starboard).
H. P. cruising turbine.
I. P. cruising turbine.

(c) Maximum difference in dummy clearance (if any + or — )
found by checking gagings at finger-pieces by micrometer readings:

CNoTE. — ^Maximiun difference (if any) will occur under full steaming
conditions.)

Main H. P. turbine.

L. P. turbine (port).

L. P. turbine (starboard).

H. P. cruising turbine.

I. P. cruising turbine.

FIGURE 161.

Reference Diagram.

Instructions for Adjusting

Parsons Turbines.

Enlarged

**,

-»

CARE AND OPERATION OF PARSONS TURBINES. 205

(d) The working dummy clearance at the respective turbines
when the rotors are hard forward should be:

Main H. P. turbine.
L. P. turbine (port).
L. P. turbine (starboard).
H. P. cruising turbine.
I. P. cruising turbine.

(Note. — Owing to the oil clearance referred to in paragraph 5, the rotor
has a little fore and aft movement, and this should be borne in mind when
gagings or readings are taken, as the clearances given under (a), (b), and (d)
only hold good when the rotor is hard forward; this does not apply to (c),
as the difference obtained will be constant with rotor in any position between
hard forward and hard aft.)

For thickness and gagings mentioned in paragraph 7(a), (b), (c), and
(d), see instruction sheet supplied to ship.

8. The foregoing instructions refer entirely to turbines having the
contact type of dmnmy, whereas many of the latest designs now in com-
mission have the radial form of dummy fins for the L. P. ahead turbines.
This type has been in use with all backing turbines for many years and
allows for considerable end movement of rotor in relation to the casing.
By fitting a similar type of dummy packing to the L. P. ahead
turbines, the question of adjustment has been eliminated.

The two halves of the adjusting block are locked together and
the rotor collars bear all around the brass rings.

It is usual to allow about .025 inch oil film clearance between the
steel collars of rotor shaft and of the brass rings.

Further a steel pointer is arranged in the air gap at forward
end of turbine and is directly opposite a line scored on rotor. Similar
lines at forward and aft sides of central line give the safe working
limit as regards the end movement of rotor.

J. OPENING OUT OF TURBINES FOR INTERNAL INSPECTION.

Overhead gears are provided to lift the rotors and covers or top halves
of all cylinders, but not the turbine complete. These gears must be worked
so that each cover and rotor is lifted parallel and peipendicular to the hori-
zontal joint of the cylinder. Graduated pillars are usually fitted at the cor-
ners of lower half of the cylinders to guide the covers, and brackets are sup-
plied to bolt to the bearing supports and fit against the rotor shaft journals
to guide the rotors.

A few installations in torpedo-boat destroyers are arranged so that the
main exhaust pipe connections and the turbine casing covers open on hinges.
In such cases guide pillars are not required, but in overhauling such an instal-
lation care has to be taken to ensure that the various parts, when hinged open,
clear each other. Further, the covers when hinged open should be secured so
that the lifting tackle is partly taking the weight of the casing off the hinges.

206 STEAM TURBINES.

Each Turbine Should be Opened Out, as follows:

1. Remove all pipe connections attached to cylinder casings which
will be in the way of lifting cover or rotor and blank off all openings with
wood (not waste) to prevent any foreign matter getting inside.

2. Remove lagging and all bolts aroimd horizontal joint of cylinder.

(Note. — ^When opening out L. P. cylinders for inspection care must be
taken to remove all the horizontal flange bolts in the astern cylinders, where
they are fitted in the exhaust end of the L. P. casing.)

3. Dust down thoroughly to prevent any dirt getting inside while
lifting the cover.

4. Starting bolts are provided on each cover, which should be put
into use until the cover is an eighth of an inch off the face of joint.

5. Fit guide pillars in corners, and, while hoisting, check the dis-
tance cover has traveled to ensure a level lift.

6. Where gland sleeves are fitted in halves, care should be taken
when lifting the cylinder covers that the top halves of the gland sleeves
are not lifted with the covers, otherwise they may drop off, resulting in
damage both to the rotor and gland. This, however, does not necessitate
removing the gland casings where these are external and bolted to the
cylinder ends.

When the cover is clear of the rotor and ready for removing,
orders should be enforced that all exposed external parts shall be
covered with clear canvas.

7. Transport cover and land, or secure as the arrangement may
provide.

8. Remove both bearing caps and top halves of gland sleeves (where
in halves) ; fix the rotor guide brackets in position in such a manner that
the dummies or blades cannot foul while lifting the rotor.

Care must be taken that the rotor lifting gear does not foul the
end of the diunmy ring.

9. Lift the rotor, and when the rotor shafts are clear of the bearings
remove the bottom halves of the glands if the inner ends of same project
beyond the end of the rotor drum or dummy ring; then complete lifting,
and in cases where the gland sleeves are made in one piece, slide to one
side and examine gland rings.

10. After inspection, scrape all jointing material from the flanges
and gland casings or pockets, clean down thoroughly, carefully examine
to ensure that no small articles are left in the cylinder, and blow out any
dirt. Examine all drain holes in cylinders, particularly those in the
astern steam belt and at the corner of each expansion in the L. P. cylin-
der, and clear where necessary. Clear all drainage holes or grooves in
rotor drums and wheels. Then apply graphite paint (or some suitable
substance) to the gland casings where these come into contact with the
gland sleeves.

11. Replace the gland rings and sleeves (where these are in one piece)
and lower rotor into place. Where the gland sleeves are made in halves,
the rotor is first to be lowered until the dnuns or dummy ring is below the

CARE AND OPERATION OF PARSONS TURBINES. 207

level of the gland sleeves ; and the bottom halves of gland sleeves are then
put into place, and after the rotor is lowered the top halves should be
put into position ready to engage with the cover. Where the ends of the
rotor drum or dummy ring will clear, the lower halves of the gland
sleeves may be inserted before lowering the rotor. Replace the canvas
covers on rotor and journals.

12. Thoroughly clean flanges, gland casings, bolt holes, etc., in cover,
transport it into position for lowering, lower it (guiding it in the same
manner as when lifting it) to within about one foot of the joint.
Graphite paint (or equivalent substance) should then be applied, by hand
only, to the flanges of the cylinder; care must be taken that there is no
grit in the paint. Before finally lowering the cover see that the dummies
are about midway in the grooves, and when in this position lock the rotor
with the adjusting gear to prevent it from moving forward or aft. Lower
the cover and see that the gland sleeves are in the correct position for
engaging with the covers.

In the case of high-pressure turbine joints, a manganesite paste
has been found to give very satisfactory results. The manganesite
is groimd down from a cake to a powder and mixed with boiled oil
to the consistency of a thick cream. Special care has to be taken to
see that there are no solid particles in the paste ; and it is best applied
by hand.

13. Replace all bolts in their respective positions according to the
niunbers stamped on them and gradually tighten hard up.

Where Glands Are Bolted to the Cylinder Casing They May be Overiiauled
Without Lifting the Cylinder Cover, as foUows:

1. Remove bolts for securing top half of gland to cylinder cover and
bottom half of gland.

2. Lift top half vertically until it is clear of the gland-sleeve spigot,
and then withdraw forward or aft so that no damage may be done to the
gland strips.

3. Lift the top half of gland sleeve vertically imtil the strips in the
gland sleeve are clear of the strips on the rotor, and then withdraw for-
ward or aft.

Fit temporary safety liners into the bottom half of the gland
sleeve to protect the thin edge of the strips from being damaged.
Turn the sleeve around the shaft upon these liners, and remove in the
same way as the top half sleeve. The gland rings and strips may
then be examined.

(Note. — ^In some turbines the top half of gland sleeve has no spigot, and
in this case the gland pocket top half may be withdrawn forward or aft
without first lifting vertically. With this design studs are usually adopted
for securing the top half of tiie gland to the cylinder casing, and bolts or tap
bolts are adopted where the gland pocket must be first lifted vertically irntu
it is clear of the sleeve spigot. In some glands the part which surrounds the
rings is made in tiiree segments, and by removing tiie two top segments, the
rings may be taken out and examined without disturbing the other parts of
the gland.)

208 STEAM TURBINES.

4. Thoroughly clean the gland parts and part of the cylinder where
the gland fits and apply graphite paint (or some suitable substance) to
all the parts of the gland and cylinder which come in contact with each
other, and then replace.

TURBIXE FiTTIKGS.

Steam Starainen:

They should be occasionally examined and cleaned as necessary.

Bridge Gages:

For measuring the wearing down of the bearings, bridge gages are
supplied. These gages are made suitable for placing at each end of tur-
bine over the rotor, either at the bearings or at the space between the
gland and the Ijearing cap. Gage the clearance between the projecting
part on the bridge gage and the rotor, and by comparing this measure-
ment with the reading or measurement engraved on the nameplate
supplied with the bridge gage, the amount of wearing down will be
ascertained.

Cut-out Gear:

Where cut-out or trip gear is fitted, this should be occasionally tried
in port when steam is up and the turbines revolving to see that it is in
working order and that the mechanism has full control over the throttle
valve. To try this gear, ease back a little the spring contained in the
governor, thereby permitting the governors to lift at less than their nor-
mal working revolutions. When making adjustments with governors,
and if the line shafting and propellers are imcoupled, special care must
be taken when admitting steam to the turbines to guard against the pos-
sibility of the rotors running away.

L. P. Turbine Drains:

Care should be taken to regularly examine and clean the non-return
valve between L. P. turbine drain and air-pump.

Expansion of Turbines:

Sliding feet are provided at one or both ends of the turbines, accord-
ing to the arrangements of the tiu'bines, and in some cases provision is
made for oiling these feet. These sliding feet should be occasionally
examined to see that no dirt or other matter collects in such a wav as to
interfere with the free expansion of the turbines.

Adjusting Blocks:

In some turbine installations no adjusting blocks are fitted in certain
turbines. For instance where an H. P. astern is attached to an H. P.
ahead turbine. Turbines having no adjusting blocks are usually provided
with an indicator for showing the relative position fore and aft between
the rotor and cylinder blades, and should such a turbine be turned while
disconnected, particular care must be taken to see that the rotor is not out
of its central position more than the amount stated on the indicator.

CARE AND OPERATION OF PARSONS TURBINES. 209

Removing Propellers:

K. GEARING.

In connection with installations having mechanical reduction gearing the
following points require attention:

1. The pinion and gear-wheel journals should be checked regularly
with the bridge gages to note the amoimt of wear.

2. Attention should be paid to ensure that the tips of the oil sprayers
are free from dirt. In most cases means are provided wherebv each
nozde can be withdrawn and examined witiiout stopping the machinery.

3. The temperature of the oil from drain well of gear box to be noted
at regular intervals.

4. Do not allow tips of gear-wheel to run in oil. This will tend to
heat up the oil supply excessively.

5. Attention to be paid to ensure that the gear-wheel and pinion
shafts are free to move in a fore and aft direction.

6. Where the gearing is used in conjunction with a cruising turbine,
the following points require attention:

(a) In most cases clutches are provided so that the cruising unit
can be disconnected when the main engines are in use.

(b) Before throwing in a clutch warm up cruising turbine
thoroughly.

(d) When connecting up, if clutch is of the jaw type, it is very
advisable to stop the main shaft to which the coupling is to engage
and connect up the turning gear of cruising unit, using this to bring
the teeth into line so that the claws will engage.

(e) Remarks regarding the operation of the cruising turbine
will be found to apply to the direct drive type.

CHAPTER XVII,

INSTRUCTIONS FOR THE CARE AND OPERATION OF

CURTIS TURBINES.

A. FORCED LUBRICATION.

Before Starting the Oil Pumps:

1. See that there is no water in the bottom of the oU drain tanks or
in the bottom of the tanks (settling or storage) from which any extra oil
will be taken. When water is drawn from these tanks, about an inch
of oil should be removed with it. This oil may be filtered and used again,
but preferably should be used for auxiliary machinery.

2. Keep the oil suction to pumps well covered to insure an abimdant
supply of oil at all times. Soimdings of the drain and settling tanks
should be frequently taken after starting the oil pumps. Settling and
storage tanks should be fitted with gage glasses, and the drain tanks
fitted with a graduated float in order to obtain the amount of oil at any
instant.

Before Turning the Turbines:

1. Start oil pumps and examine oil system to see that all bearings
are being supplied with oil and that there is no oil leakage.

2. Regulate speed of oil pumps to obtain a pressure of from five to
ten pounds at the bearings and adjusting blocks. An excessive pressure
may result in oil leakage and waste from bearings.

After Starting Oil Pumps:

1. Note amoimt of oil in drain tanks. This should be kept at from
40 to 100 gallons, depending on size of installation.

2. See that required pressure is maintained at the bearings.

When Under Way:

1. Discharge oil through cooler when oil temperature reaches about
90^P.

2. Start oil cooler circulating pumps or open connection from dis-
charge of main circulating pumps. Open pet cock on oil cooler to insure
that water is circulating.

3. Frequently examine sight feed glasses at bearings to ascertain if
oil is flowing freely.

4. Regularly note temperature of oil leaving bearings where ther-
mometers are fitted. A fair nmning temperature at full speed is from
110°P. to 130°F.

5. Strainers should be frequently overhauled and cleaned out.

6. Frequently clean dirt and grit from oil reservoirs imdemeath
bearing to prevent clogging of oil drain-pipes.

7. Increase oil pressure to about 35 pounds at the bearings.

211

212 STEAM TURBINES.

After Steaming:

1. The oil pumps should be kept going to free the bearings and
journals of any water. If practicable, it is a good plan to force new oil
through the bearings just before securing the oil pumps.

2. Frequently test oil from bottom of drain tanks for thickness.
Remove all thick oil and renew supply from settling or storage tanks.

3. Make sure that oil system is well supplied with oil, and that no
leakage takes place.

B. WARMING UP.
Before Starting:

1. See that jacking gear is connected.

2. See that oil pmnps are working properly and that all barings are
supplied with oil.

3. Start main air and circulating pumps and maintain a vacuum of
about five inches.

4. Open all turbine drains and start drain pumps or open suction
from main air-pumps to turbine drain lines.

5. Admit sealing steam to shaft glands and maintain pressure of
about five poimds. Open gland drains sufficiently to carry off water of
condensation.

6. Open warming-up steam valve to each end of each turbine.

7. If jacking gear will stand it, jack rotor continuously for about
an hour. If jacking gear will not stand continuous jacking, jack turbine
one-quarter turn every 10 or 15 minutes for about an hour.

8. Disconnect jacking gear and warm up ahead and astern throttle
valve. Admit sufficient steam to turn rotors slowly, first ahead and then
astern. Continue turning the rotors in this manner for about two hours.

9. When no power jacking gear is available use method described
imder paragraph 8.

10. When turbines are sufficiently warmed and usual precautions
taken to see that everything is clear, test out all turbines by giving a few
turns ahead and astern and report ready.

11. Every precaution should be taken to have steam pipes and tur-
bines free of water before getting under way.

C. MANEUVERING.
When Maneuvering:

1. The turbines are operated by means of the main throttles or by-
passes. For turbines fitted with individual nozzle control valves for the
first stage nozzles, at least one-half of the nozzles should be opened.

2. To go ahead, open ahead throttle slowly.

3. To go astern, close ahead throttle and open astern throttle.

D. CONTINUOUS RUNNING.

After Getting WeU Under Way:

1. Open sufficient first stage nozzles so that when making approxi-
mately correct revolutions, the pressure in the steam chest (absolute) is

CARE AND OPERATION OF CURTIS TURBINES. 213

approximately four times the pressure (absolute) in the first stage.
Adjust to required revolutions with the main throttle.

2. Adjust steam to glands so that there is just a " feather '' of steam
escaping.

3. After steady running for about 15 minutes, close turbine drains
and shift auxiliary exhaust from the condenser to the tiu-bine.

E. FULL SPEED.

When Disconnecting Cruising Turbines and Shifting to Main Turbines Only:

1. Crack main ahead throttle valve and allow steam pipes to main
turbines to drain thoroughly.

2. Open main turbine throttle valves slowly imtil the revolutions start
to increase then close throttle to cruising turbine and disconnect clutch.

3. Regulate first stage nozzles and steam chest pressures to give
desired revolutions.

4. Open drains of cruising turbines and allow this turbine to drain
thoroughly.

F. TXJEBINES IDLE.

1. To reduce to a minimiun the corrosion of the interior surfaces of
turbine casings and rotors, it is of the utmost importance that their
interior spaces be kept thoroughly dry while the turbines are not in oper-
ation. To this end, after securing the main turbines, the air-pmnps should
be continued in use for about two hours, maintaining a moderate vacuum.
When it is expected that the main turbines will not be required for use
again under steam within 48 hours, the main aii*-pumps should be
employed daily for about 15 minutes to produce a moderate vacuum in
the condenser and turbines in order to dry them out. During this time,
all turbine drains should be opened and the suction from the main air-
pmnp to the turbine drain line opened. Care should be taken at all times
to see that the turbine drain to bilge is closed and that the water in the
engine-room bilges does not rise above the turbine drain to bilge.

2. The turbine should be jacked over daily and brought to rest at
different positions on any two consecutive days.

3. Oil should be piunped through the bearings each time the tiu*bines
are jacked over. This prevents the oil from gumming and water from
collecting in the bearings. Water in contact with the journals will cause
corrosion of the journals with the resulting dangers of hot bearings and
rust getting into the oil in the form of grit.

G. GENERAL.

Lifting Casings. The U. S. Navy Instructions require that turbine cas-
ings be lifted once every two years.

When the casings are lifted, the greatest care should be taken to prevent
dirt and foreign substances from getting into the turbine. The engine-room
hatches should be roped off and the turbine covered with canvas when no
work is being done.

214 STEAM TURBINES.

Bemove all pipe connectioiis attached to cylinder casings which will inter-
fere with lifting the casing or rotor, and blank off all openings with wood (not
waste) to prevent any foreign matter from getting inside.

Remove lagging and all bolts aroimd horizontal joints of casings. When
opening the L. P. casings for inspection, care must be taken to remove all
horizontal flange bolts in the astern casings in the interior of the turbines in
those cases where astern turbines are fitted in the exhaust end of the L. P.
casing.

All nozzles, stationary blading, and interior surfaces of casings, and all
moving blades and the exteriors and interiors of aU rotors should be carefully
examined. The interior of casings may be thinly coated with cylinder oil
applied with a brush. If any corrosion appears, it should be cleaned to the
bare metal with kerosene, and the depth of any pitting should be measured
and noted.

All joints should be scraped clean, and when the casing is put together,
great care should be taken to make the joints tight. The best preparation for
making joints is manganesite. Sheet packing should not be used as its thick-
ness will displace the upper half of the casing.

Casings. The inspection hole plates on the casing should be ranoved and
the inside of the casing examined at least once a quarter.

Foreign Subttances. When any part of the turbine is open, the greatest
care should be exercised to prevent any foreign substances from getting in.
Inspection plates should not be left off overnight or for any considerable
length of time. When inspecting a turbine with the rotor in place the person
making the inspection should see that all foreign substances are removed from
the pockets of his clothing.

Steam Strainers. Steam strainers should be examined about every six
months.

Shaft Glands. Carbon packing should be removed, cleaned, and refitted
after about 100 days of steaming. The ends of the segments should be dressed
down until there is from 1/16 inch to 1/8 inch clearance at the ends. This will
allow the segments to fit the shaft snugly as they wear. Springs of the seg-
ment holders should be replaced if corroded or weak.

Oil Strainers. The oil strainers should be removed and cleaned after
each run.

Steam QiesL In turbines fitted with individual nozzle control valves,
the valve stem packing should be kept tight and in good condition. The steam
chests should be opened and the nozzles and nozzle valves examined and
reground if necessary about once every six months.

H. adjustments;

There are only two adjustments to be made; the axial clearance and the
bearing wear.

Adjustment of Axial Clearance. The rotor is held from moving axially
by the thrust bearing and adjustment is made by means of the nuts holding
the side rods. The normal running condition is with the clearance on each
side of moving blades about equally divided, with slightly greater clearance
on the forward side of the moving blades than on the after side. Peep holes

CARE AND OPERATION OP CURTIS TURBINES. 215

are provided for examining these clearances and a clearance indicator is fitted
to show the position of the rotor relative to the casing. With the turbines
thoroughly heated and jacking gear connected, haul the turbine rotor forward
by means of the adjusting nuts on the side rods, care being taken to see that
both nuts are turned an equal amoimt, each being turned about one-quarter
of a turn in succession. Start jacking the turbine and continue hauling for-
ward imtil the rotor rubs. Then take reading of clearance indicator. Next
force the rotor aft in the same manner as above until it again rubs. Take
clearance reading. The difference between the two clearance readings gives
the total clearance in the turbine. About five-eighths of this clearance should
be on the forward side of the moving blades. Add this amoimt to the reading
of the clearance indicator when in the forward rubbing position; this gives
the indicator reading for the running position. Haul turbine forward imtil
this reading is obtained on clearance indicator and then secure.

Another method of obtaining this clearance is to remove peep holes at
various points and measure the clearance by means of feelers.

The clearance should be taken and recorded once each watch while under
way.

The clearance indicator consists of a spindle through a stuffing box in
the forward head of the turbine casing, and may be turned or moved fore and
aft by means of a handle on the outer end. Attached to the outer end is a
pointer or graduated drum which, by means of a suitable scale, indicates the
amount of movement, in a fore and aft direction, of the spindle. The inner
end of the spindle has a semicircular section. Normally, the spindle is pulled
forward and the semicircular section turned up where it rests against a stop
in the casing. In this position the drum, or micrometer, is adjusted to read
zero.

To take a clearance reading, the spindle is turned around until the semi-
circular section is down, in which position the spradle is free to move fore
and aft. Push spindle aft imtil it touches the rotor and read clearance indi-
cator : this reading is the distance from the indicator stop to the rotor. From
this reading subtract the indicator reading when the turbine was in the for-
ward rubbing position. This difference is the clearance on the forward side
of the moving blades.

The end of the spindle, when taking a reading, bears against the forward
side of the run of the first stage wheel or the forward end of the L. P. drum
rim, consequently it is liable to wear down. This necessitates the frequent
adjustment of the drum for the zero reading.

The clearance on the. forward side of the moving blades is usually from
one-tenth to two-tenths of an inch at the H. P. end of the turbine. This is
increased to as much as half an inch in the L. P. end. This increase is made
to allow for the difference in expansion between the rotor and the casing ; the
rotor and casing being tied together by the thrust bearing at one end of the
turbine only.

Adjustment of Main Bearing Wear. The turbines are originally
installed with the bearings machined so that the center line of the rotor is
about 0.005 of an inch higher than the center line of the casing, thus allowing
this amount of wear to occur and leave the rotor centered in the casing. With

216 STEAM TURBINES.

good care and no hot bearings, no adjustments of main bearings should be
required for at least a year. If the rotor drops 0.02 of an inch below the
central position, the rotor should be raised by placing shims under the bearing,
or new lower brasses fitted. For checking the height of the shaft, the distance
from the shaft to a fixed point on the bearing base, directly underneath the
shaft, should be carefully measured. After each run, this height should be
cheeked at all main bearings.

Shims are provided between the lower brasses and the bearing caps, so
that the caps may be adjusted as the lower brass wears.

The radial clearance of the tiu-bines is considerably more than the per-
missible drop of 0.02 of an inch given above, and the objection to permitting
a greater wear is that the diaphragm bushings would be ground out on the
bottom side, thus increasing the steam leakage from one stage to the next.
The wear on the bushings would cause no operating trouble as they are so
designed to wear down easily, but the increased steam leakage from stage to
stage, due to the increased clearance through the diaphragm bushings, would
materially affect the economy. An increased clearance of 1/16 of an inch
would increase steam consumption of the turbines at least 5 per cent.

218 APPENDIX.

effective types of turbines, which are really jacketed water wheels. In this
latter branch the advance was marked and the conservation of power, sim-
plicity of parts, saving of space, and other desirable features of water turbines
seemed to point out the method by which steam could be similarly employed
to move turbines. Theoretically, the analogy between the use of steam and
water in the same mechanical form of structure seemed clear. But the analogy
was a mere surface one. In reality steam and water are, from the standpoint
of motive power, essentially different. The motive power of water is gravity,
that is, pressure exerted in one direction, while that of steam is expansion,
that is, pressure exerted in all directions. The laws of hydraulics, as applied
to water wheels, were well known and comparatively simple, while, as the out-
come proved, the laws of steam as applied to turbines were not known or
appreciated. Moreover, water is unchanging in volume under different pres-
sures; thus the velocity of the flow or jet of a stream is in inverse proportion
with the cross-section of path provided for it. But when velocity is developed
by diminution of pathway, it must be at the expense of a local deficit of pres-
sure. Whenever the path contracts, velocity increases and pressure diminishes
by a determinable amoimt. But with steam all is different. Only in few
instances does steam act in the same way as water, and eveii where it does
there is always present an intricate and mathematically inexpressible rela-
tionship between steam volume and pressure to complicate the relation between
cross-section of path and velocity of flow. Experience has further shown that
steam turbines involve further perplexities in the form of absorption of energy
caused by virtually every bend, change of cross-section, and tiny eddy. That
steam could be used as a propulsive rotary force was of course well and long
known. From the record before us we learn that a crude form of steam tur-
bine was described by Hiero of Alexandria 120 years B. C. which used steam
as a kicking or propulsive force from which the discharging wheel reacted
in the same way that rearwardly discharged water drives in the opposite direc-
tion an ordinary rotary lawn sprinkler. So also, as early as 1629, the turbine
of Branca, an Italian, showed how steam could be jetted against a vane to
produce forward rotary motion. But while these two, almost forgotten,
instances strikingly show that the two broad principles of operation on which,
as we shall see, all modem turbine development is based, were thus known,
no practical and efficient steam turbine, working on either principle, was
developed prior to 1884. And this absolute dearth of outcome cannot be
attributed to lack of effort — for in 1896, the date of the first patent in suit,
Sosnowski's Treatise ** Roues et Turbines a Vapeur '' gave a list with illus-
trations of 300 prior steam turbines. But apart from those of two inventors.
Parsons and De Laval, referred to below, no one had, in this broad field of
effort, produced a practical and efficient device. The magazine Engineering,
in an issue of August, 1894, said :

** Most engineers who are approaching middle age can remember
when the idea of making a successful steam turbine was classed with the
search for the philosopher's stone. It was known of course that such a
motor could be readily made to work, but the consumption of steam was
excessive because the motive fiuid left the apparatus at a high velocity

and with much of its energy imutilized What was wanted was to

construct a wheel that woidd run several times as fast as the spindle
of a mule, and most mechanics regarded the matter as impossible."

APPENDIX. 219

The experts appointed by the Court of Commerce of the Canton of Zurich,
Switzerland, in certain litigation involving steam turbines reported to that
court that ** the art of steam turbines was first brought into existence by Par-
sons and De Laval/' Indeed, this is in substance conceded by respondent's
expert, who, in answer to the question whether he agreed with the statement
made by Neilson in his work on steam turbines (4th Ed., 1908) that the Parsons
and De Laval turbines were the only two turbines which had been made on
other than an experimental scale up to 1895-6, said :

** Limiting your question to steam turbines I should answer it that
the Parsons steam turbine and the De Laval steam turbine are the only
ones that I know of that were being manufactured prior to 1896, that
are being manufactured for commercial use to-day.''

Passing by, therefore, the fruitless effort of prior inventors we take up
the practical and effective stage of the art with Parsons and De Laval. Par-
sons, the real pioneer of one branch of the art, was a British subject who in his
English patent. No. 6735 of 1884, gave the world its first effective steam turbine.
A study of this patent shows that Parsons disclosed no undiscovered law of
nature or any novel principle of operation. His basic principle of operation
was the simple principle of reaction shown in prior devices, but his being the
first real practical and efficient device in a barren field of effort. Parsons has
been justly regarded as the pioneer of the steam turbine art. As well said by
one of complainants' witnesses:

** It can, therefore, be said that although Parsons did not introduce
principles not known prior to his invention, he designed an efficient reac-
tion turbine ; whereas, in all the structures devised previously, no efficient
conversion of the energy of the steam into mechanical work was possible. ' '

To the same effect is the testimony furnished by respondent in the address
of Bateau, a French savant, in his Chicago address in June, 1904, who, in
speaking of the production of an imworkable speed where steam expansion
takes place in a single stage of a single wheel, says, evidently, from the context,
referring to Parsons :

** A consideration of these circumstances has induced inventors to
divide the expansion of the steam into successive stages, and thus to
produce turbines with multiple wheels, which are nothing but a series
of simple turbines mounted upon the same shaft driven successively by
the same current of steam. This design of multiple turbines is by no
means novel. It will be sufficient to mention the name of Tournaire, a
French mining engineer, whose theoretical description to the Academy
of Science in 1853 of a reaction turbine with multiple wheels is surprising
when the description is compared with the Parsons turbine brought into
use 30 vears later."

Parsons provided a large outer shell or chamber provided with a central
shaft and adapted to receive steam peripherally at one end and exhaust at the
other. Mounted on the shaft were a large niunber of sets of moving vanes
properly angled, through which the steam passed as an annulus, thereby
imparting motion. The outer ends of the moving vanes of each set fitted closely
to the shell, prevented steam escape and necessitated it going through the inter-
vane passages. Following each set of movable vanes were corresponding sets
of stationary vanes attached to the shell at substantially such an opposite angle

220 APPENDIX.

as deflected the steam and caused it to pass through a succeeding set of movable
vaneSy so co-related to the first movable set as to aid in revolving the shaft. The
power of steam to impart motion is based on pressure, and pressure is but
expansion restrained. It follows, therefore, that, in the principle of operation
of Parsons turbine, as the steam passed from the high-pressure end of the
chamber through the successive sets of movable vanes to the exhaust it expanded,
decreased in pressure, and imparted rotary motive power to the movable vanes.
And just as in a common lawn sprinkler the passage of the water through a
turned passage caused the wheel to kick or react in a contrary direction, so in
Parsons turbine the expansive force of the volume of steam passing through
a revoluble vane, angled at the discharge, reacts and causes the vane to rotate
in a course opposite to the line of discharge. It is this drop of pressure, and
the consequent different stages of pressure between the inlet and outlet side
of the movable vane, that characterizes and is the differentiating earmark of
reaction turbines. This drop pressure, as the underlying principle of the reac-
tion turbine, is well set forth by complainants' expert, who says:

** The essential difference between reaction and impulse turbines is
the one as to how mechanical work is obtained from the energy of the
steam. In both types of turbines the initial energy is in the shape of
steam under high pressure, either in a dry or saturated or superheated
condition. In a reaction tiirbine this steam is permitted to pass through
a number of rows of buckets in such a manner that the pressure of the
steam on the entering side of the bucket is quite different from the pres-
sure of the steam upon the leaving side of the bucket, and rotation, that
is, mechanical work, is secured, due to the drop of pressure of the steam
in passing through the bucket."

It follows, therefore, as stated in Jude on The Theory of Steam Turbines
— London, 1906 — page 16, and conceded by respondent's expert, ** In the reac-
tion turbine there is a transformation of potential energy into kinetic energy
within the rotating member.*' Such turbines have other characteristics. For
example, from this pressure drop in reaction turbines it follows that the entire
steam passage between the movable vanes must be fiUed with steam and as
stated by M. Bateau: " It is of coiu^e necessary in order to produce a good
dynamic eflSciency, to operate in such a manner that the peripheral speed of the
turbine be not much inferior to the circulation speed of the steam." It will
thus be seen that what Parsons did was to take the well-understood principle
of a reaction turbine and its single chamber with a single wheel which operated
at an unworkable speed and by increasing the number of such wheels in effect
subdivide an entire chamber into a number of separate, pressure-staged sec-
tions, for such, in reality, was the effect of the pressure being different on the
opposite sides of every set of movable vanes. It will, of course, be noted that
the Parsons or reaction pressure turbine operated on a fimdamentally different
principle from a turbine, for example, of Branca 's type. In the latter the pro-
pulsive force is the impact or impulse of a jet of steam against the movable
vane. The steam is blown against the vane in the form of a jet in a manner
resembling the impulse given to a projectile by an explosion in the barrel of
a gun. This is well stated by complainants' expert, who says:

** The powder charge on being fired develops a large pressure in a
confined space similar to the pressure of steam in a boiler and steam pipe.

APPENDIX. 221

The projectile is forced outward by the expansion of this charge, that is,
the pressure energy available is utilized in producing movement of the
projectile. The projectile is moved by the reaction of tiie charge just
as tiie buckets of a reaction steam turbine are moved, due to the reaction
of the steam. In both the gun and reaction turbine the energy in the form
of pressure acts by reaction upon the piece on which work is to be per-
formed, in one case causing linear motion, in the other case circular
motion, and in both cases i£e initial pressure drops to the pressure of
the exhaust or atmosphere. The energy represented by the drop of
pressure from initial to exhaust is used to produce mechanical work.
In both the gun and reaction tiu*bine an important requirement for
an efficient conversion of pressure energy into work by the reaction
principle is close clearance between the moving and stationary parts so
as to prevent leakage of the pressure energy. After the projectile leaves
the gun it possesses velocity energy. This is similar to the velocity energy
of the steam jet as it leaves the nozzles of an impulse turbine. The nozzles
give the steam a large velocity at the expense of the pressure energy of
tiie steam ; that is, the steam in passing through the nozzle drops in pres-
sure from the initial pressure to the exhaust pressure and in expanding
to tiie exhaust pressure produces a high velocity of the steam.''

It will thus be seen that the impulsive force is created not in the vane
passage, but in the passageway into the chamber. This is conceded by respon-
dent's expert, who, following Jude's work cited above, says: ** In the impulse
turbine the transformation of potential energy into kinetic energy takes place
wholly or only in fixed passages prior to entry into the rotating member."
As therefore vane motion in impulse turbines is caused by the jet impulse as
distinguished from the expanding voliune of the passing steam in a reaction
turbine it follows that the entire vane passageway of the former need not be
filled. It also follows that the jet speed must be greater than the vane speed,
otherwise no power would be drawn from the jet by the vane. It is proper
to say that in making these general statements as to these two types of turbines,
we have not overlooked the fact that reaction turbines may have some impulse
and impulse ones some reaction. But such respective reaction and impulse
are negligible. The matter is well stated by complainants' expert, who says:

" The facts of the case are that it is an accepted fact among all
engineers conversant with the steam turbine art that the impulse turbine
derives its power chiefly from the impulse effect of the steam; some
impulse turbines may work with a verv slight reaction effect and that
all reaction turbines abstract work chiefly from the reaction force of the
steam, although every reaction turbine has a small amoimt of impulse
due to the velocity of steam flowing through the turbine. This is abso-
lutely necessary because if there were no velocity of flow, steam would
not pass through a reaction machine. The velocities in a reaction turbine
are extremely low, and, therefore, the impulse effect is small, whereas the
velocities in an impulse turbine are extremely high and the reaction effect
or pressure drop of the steam while passing through an impulse turbine
is so slight that it is entirely negligible."

But up to and succeeding Parsons, patented impulse turbines had been as
inefficient as reaction ones had been before Parsons made the latter practical.
This inefficiency of impulse turbines was due to the characteristics of steam
subjected to the structural limitations, the restricted passageway which created
the jet. This is clearly explained by complainants' expert, who says:

222 APPENDIX.

^^ When water^ steani^ or any other fluid in a reservoir approaches
constricted outlet, it must do so along converging lines. Althou^ there
may be no converging solid walls and the outld; may be even a plane
orifice, the cross-section of the path of the fluid, converging simultane-
ously toward the outlet from all directions, is a decreasing one. Hence
the fluid undergoes acceleration as it approaches. To supply the kinetic
energy involved in this acceleration, its pressure must decrease. In the
case of water, as already noted concerning the Pelton (water) wheels of
the West, there is no known limit to the intensity of pressure which can
be converted completely and eflSciently into velocity by such a simple
constriction of path. With steam, however, this conversion can proceed
only until the initial pressure has fallen by some 43 per cent, with a
conversion of something like 15 per cent of the avaiktble potential energy
into kinetic form. Beyond this point, no further reduction of pressure
against the outlet can further accelerate the flow. The reason for this is
that the reduction in pressure upon the steam approaching the outlet
leads to an increase in its volume, and this increased volume accentuates
the congestion. Up to the so-called * critical ' point, this increase of con-
gestion is not enough to more than hinder and complicate the accelera-
tion. At the critical point, however, it becomes prohibitive. The steam
expands too rapidly to get out of its own way, imtil the constriction has

been passed The critical pressure occurs with fair constancy, at

about 43 per cent of the initial absolute pressure. The critical velocity
is usually found between 1350 and 1400 feet per second ranging upwardly
toward 1500 feet imder high initial pressures and downwardly toward
1300 feet under initial pressures below atmospheric. The critical area
varies widely, from small under high pressure to large under low
pressure.''

Stating this in terms of plain working result the impulse turbine of the
old art could only utilize 15 per cent of the potential possibility of steam, a
result which, apart from other objections, barred its practical use. It will
thus be seen that no matter what the form of prior impulse turbines, or how
instructive and prophetic, read in the light of after diswveries, the statements
of their inventors may appear, they were all in reality and necessarily ineffec-
tive, because they were, in the then knowledge of steam, based on a principle
of operation that could only end in failure. In this barred state of the impulse
turbine art came the great, radical, and, at the time, inconceivable disclosure
of De Laval. Like all great inventions it was simple, but with that simplicity
was a practical change that scientifically and commercially was startling.
Mechanically all De Laval did to the impulse turbine was simply to diverge
the outlet end of the steam passage; in steam dynamics his great discovery
was that, beyond the critical point of steam, velocities can be accelerated at
the expense of pressure energy, if the pathway is diverged. Before his dis-
closure it was supposed, and not without some basis for such supposition, that
a diverging nozzle would retard steam from creating kinetic energy, for such
seemed the effect of a diverging outlet on a jet of water, and we now know
that an extension of De LavaPs diverging nozzle beyond limits now well imder-
stood makes his process ineffective. So revolutionary was De Laval's theory
that the application for an American patent upon it was met by the objection
of the Patent Office that ** The object of applicant's alleged invention will
apparently be defeated by the construction shown and claimed, since the fall
of pressure due to expansion will necessarily lessen the velocity of the steam

APPENDIX. 223

at the point of impact with the wheel and consequently the * vis viva ' of the
steam will tend to be a miniTninn rather than a maximmn.'^ To this De Laval
replied, saying:

** The characteristic feature of applicant's invention may be
expressed in a few words, thus: he expands the steam before it reaches
the turbine and converts its pressure into velocity before the steam is
required to do any work, while heretofore the steam was principally
expanded in the turbine or other engine which was actuated by the pres-
sure of the expanding steam. Applicant has made the discovery that by
a flaring nozzle practically all the pressure can be converted into velocity,
while before it could only be expanded down to 57.7 per cent of the initial
pressure, and that a jet can be produced which is no longer capable of
expansion, but which has an enormous velocity and the vis viva of which
can be economically utilized. *'

Since, as will hereafter appear, the patent of Curtis is based wholly on a
turbine of the De Laval type, the fact of De Laval's absolute departure from
all prior inventive effort is vital to a just appreciation of what Curtis subse-
quently did to supplement and utilize De Laval's discovery. This warrants
our dwelling in such detail on the revolutionary character of De Laval's work.
This is fairly stated by complainants' witness, who says:

** De Laval's original application, which was filed May 1, 1889, was
met by the examiner by complete skepticism as to its operativeness. The
effect of the conical convergence of the nozzle was held by the examiners
to be the exact opposite of that alleged by De Laval. Further, the figure
57 per cent, which appeared in the application as a measure of the pres-
sure which could not be converted into velocity in the ordinary converg-
ing nozzle, was not understood by the examiner and an explanation was
caUed for. The applicant was obliged to reply at length. The figure * 57
per cent ' was supported by a reference to the treatise on thermodynamics
by Professor Herrmann, of Chemnitz (Berlin, 1879). The examiner's
misapprehension as to the action of the diverging nozzle was explained
by pointing out that even Professor Zeuner, who was then one of the
greatest living authorities on thermodynamics, had committed himself
in his publications to the same error — an error, indeed, which was then

imiversally prevalent This debate continued year after year, and

might have extended indefinitely had not the showing made at the Chicago
World's Fair removed the question from the field of academic dispute.
The patent was finally allowed June 4, and issued June 26, 1894."

De Laval's diverging nozzle resulted in producing an impulse machine
of a phenomenal character in that the now utilized power of the steam pro-
duced a speed beyond all past experience and so high as not to be permissive
on account of stress on revolving parts.

But noteworthy and meritorious as were the contributions of Parsons and
De Laval to the turbine art, their labors still left many serious objections to
their turbines, which they were unable to remove. As has been justly said in
testimony quoted below, this was not to be wondered at. In the reaction tur-
bine, as we have seen, the steam is not jetted, but is admitted at initial pressure
around the whole periphery of the chamber or substantially so and the creation
and imparting of its kinetic power depends on its passage through interspaces
of the movable vanes, for such steam as does not go by that passage is lost.
To insure, therefore, such intervane passage and to prevent passage through
the clearance between the ends of the moving vane and the chamber shell, is

224 APPENDIX.

imperative. Owing to contraction and expansion and other causes this was
attended with grave difficulty and sometimes resulted in stripping the revolv-
ing vanes. Clearance escapes, owing to the principle of operation of a reaction
turbine, could not be avoided. They could only be measureably minimized by
the most careful construction. Moreover, the intra-chamber, drop-pressure
feature of the Parsons chamber, subjected it to the mechanical objection of
axial or endwise thrust. This was due to the fact that there was a difference in
pressure — a pressure drop — ^between the inlet and outlet side of the vane. As
the relative proportion of clearance loss to vane-capacity increased as the vane
diminished in height, the reaction turbine was restricted to large sizes. All
this is clearly shown by complainants' witness, who says of the Parsons tur-
bine, that:

** Reljdng as it did upon reaction, (it") developed its power by the
pressure of the steam upon its vanes. There was a drop in pressure
between the inlet and exit of each vane, consequently, clearance spaces
must be as fine as possible, in order to prevent excessive leakage. At the
time rotative speeds were very high compared with machinery other than
steam turbines. Consequently, it was extremely delicate and sensitive
to derangement by steam erosion, intrusion of foreign substances, etc.
The fact that it relied upon reaction also necessitated a vane speed vir-
tually equal to the steam speed. This need for high peripheral speed
prohibited the reduction of wheel diameters. Therefore, since the current
of steam must occupy the entire periphery simultaneously, the radial
dimension of ttie steam current in tiie earlier stages of the machine was
narrowly restricted. This minuteness also exaggerated the relative part
played by the clearance spaces and their leakages."

While these objections of clearance, axial thrust, and prohibitive use of
small wheels due to the use of the reaction principle were avoided by use of
the impulse principle in De Laval's turbine, yet its use also disclosed serious
objections, due to its principle of operation. The tremendous speed it
developed forbade utilization of that speed in large wheels and necessitated
the non-economic practice of counteracting or neutralizing it in the small
wheels where it could be used. It should here be noted, as throwing light on
the novel character of Curtis 's subsequent work, that this excessively high
speed of turbines was accepted as necessarily incident and the whole trend of
the engineering profession was to accept it as such. Thus in r^pondent's
proofs Bateau's address (heretofore referred to) says:

" The Girard screw-wheel, which succeeded so well as a hydraulic
motor, has given no public results as a steam apparatus. The failure of
the tests winch I just related, should not of course be ixi the least surpris-
ing. The problem was, in fact, difficult to solve, because in order to secure
an economical operation, it is absolutely necessary to attain very high

speeds of rotation If steam tiu'bines are compared with ordinary

motors both advantages and disadvantages are foimd. I would emphasize
as tiie principal disadvantages of turbines resulting from the great velocity
of rotation: (1) heating of the bearings; (2) the difficulty of driving
shafts rotating at lower speeds; (3) the difficulty in using a condenser.
I put aside for the moment the question of consumption of steam."

APPENDIX, 225

the whole rotating unit did not rotate around its geometric center, but tended to
approach the center of gravity of the rotating system. As it was impossible
to operate machinery by direct connection with the high-speeded turbine he
was driven to devise special reducing gears which were bulkier than the motor.
Indeed, as showing the grave nature of the speed problems which were never
overcome, it will be noted that the only effort of De Laval, as shown in his
German patent^ No. 84,153, to eliminate rather than accept these non-workable
speeds was his device to reduce the velocity of the jet itself before it entered
the wheel vane by mass compounding it with some passive liquid such as super-
heated water or other desired fluids to reduce its acceleration in the nozzle. In
the same line of relief Bollman, of Austria, in his patents in many countries
in Europe beginning in 1894 and ending with his American patent. No. 584,203,
of 1897, sought to introduce a mixture of air. In his work on the Steam
Turbine, Edition 189, Stodola says: ** The majority of the older patents
showed lack of knowledge of the steam flow. One idea especially led inventors
on in spite of constant failure ; to decrease the velocity of the steam by mixing
it with fluids or gases." After showing that even if they had succeeded, ** there
must be (in a particular one cited) a loss of kinetic energy that would amount
to one-half to three-fourths of the available work.'^ Stodola says:

" As patents are being taken up to the present time on this useless
idea, it is well to investigate it somewhat more closely. The mixing of
fluids must give, besides the loss due to shock, a poor performance in the
blade channels, because the individual drops of the * rain of this mixture '
must become separated from the steam mass on account of the sharp bend-
ing of its path.''

Notwithstanding then the elimination in De Laval's impulse turbine of
the objectionable features of wheel-clearance, axial thrust, and non-use in small
wheels which lessened the efl&ciency and scope of the Parsons reaction turbine,
the De Laval impulse wheel was, by its high speed, also restricted in scope in
that such speed prohibited its use in large turbines and prevented its use in
smaU ones except when accompanied by supplemental speed-reducing gearing.
It will thus be noted that great as the contributions of Parsons and De Laval
were to the turbine art, the devices of both had grave limitations. On the one
hand, De Laval could not utilize all the kinetic force his impulse turbine could
call into play, and on the other hand, the limitations of axial thrust and clear-
ance measureably coimteracted and inefficiently lessened the kinetic energy the
Parsons reactive type produced. The practical result was the restriction of
Parsons to the field of large turbine effort, of De Laval to small, and that a
field for further inventive effort remained is foreshadowed by respondent's
proof where Rateau in his Paris address of 1890, already referred to, says :

"Is it then impossible to properly satisfy at once these two condi-
tions: to utilize high speeds of flow and avoid too great losses in power?
Probably not. I am even convinced that for this class of motor, as in the
case of hydraulic motors, it will be possible without too great difficulty to
obtain an efficiency of 75 per cent. However this may be, the scheme
which will give this result is yet to he found/ ^

In this state of the art Curtis devised the turbine covered by patent
566,969, and before discussing what the device of that patent is let us state
clearly what it is not. So far as turbines meet the eye they are all substantially

226 APPENDIX.

similar, but the real test of a machine is not its physical appearance, but the
principle on which it operates. Now of the Curtis device a few things are
basic. Its principle of operation is not by pressure for Curtis has no intra-
chamber change or stage of pressure, and because it has no pressure passages
it has no clearance and no axial thrust Manifestly, therefore, it is not a reac-
tion turbine and the pressure principle of operation of that machine was not
used in it. It follows, therefore, tiiat whatever the success of Parsons in
developing that principle was in reaction turbines, it did not anticipate or
pre-empt the field of impulse turbines to which Curtis addressed himself. On
the other hand, while Cmiis's is an impulse machine, patterned after and
indeed making De Laval its avowed foundation, and using the diverging nozzle
invention of De Laval to create kinetic force, yet, at a vital point, a radical
departure is made from De Laval, and on that departure Curtis 's device rests.
For the principle of operation of Curtis 's turbines is such, and herein lies his
novel and valuable contribution to the impulse turbine art with its non-clear-
ance, non-axial thrust, simple and rugged parts, that instead of extracting
initially, as De Laval has done, a kinetic force so great as to require neutrali-
zation or reduction, he only extracts — ^and that by degrees — such power as is
needed — s, process termed hereafter pressure staging — and as such requisite
power is so extracted by degrees he utilizes the whole of such extracted power
by a process hereafter called velocity compounding. If these facts be estab-
lished it f oUows that Curtis was not anticipated by either Parsons or De Laval,
that he gave to the art a low-speed, impulse turbine, which while using the
general principle of pressure staging as Parsons had done, so used it as to
avoid clearances, axial thrust, and exclusion from the field of small turbines,
and while extracting kinetic power as De Laval had done, avoided the creation
of high speeds, wasteful non-use of potential power, and exclusion from the
field of large turbines. His device was more; in that in a turbine of simple
parts and rugged construction, Curtis combined the excellencies and avoided
the faults of both his predecessors. This in no wise refiects on the merit of
those pioneers, as is conceded by complainants' expert, Indeed, how radical
was the departure of Curtis from prior developments is simply but forcibly
siumned up in Curtis 's own testimony. He says:

** After giving the subject a great deal of thought, it seemed to me
that it would be possible to devise a machine which could be run at a much
lower speed of revolution than any turbine which I was aware of, that
would have an even higher eflRciency, sufficiently high to enable it to take
the place of the steam engine in large imits. At the same time the machine
could be made very rugged and mechanically simple, and the necessity
for small blade or bucket clearances eliminated. I remember being very
much struck with the fact that no machine having these characteristics
had yet been produced, although a great amount of thought and experi-
ment seemed to have been devoted to the subject.''

He then in effect adds with commendable frankness that he took up the
problem not as one of pioneer work, but only as an improver on De Laval,
saying:

* * I was particularly impressed with the fact that no turbines had been
built, based upon the principle of staging or pressure compounding, what
might be called generally the De Laval type of turbine, and it seemed to
me that this principle offered the true solution of the problem."

APPENDIX, 227

It thus appears that the goal Curtis had in view was an impulse turbine
which would work efficiently at a shaft speed so low as to not require speed-
reducing gear, but would conserve the potential power of the passing steam
until its use was really required. To do this he devised the novel scheme of
subdividing, in an impulse turbine, the available energy of the steam, in
transit, into a nmnber of steps or stages. This was done by producing several
successive chambers connected by diverging or parallel nozzles. In this way
it will be seen that instead of using one chamber and one nozzle, whereby the
steam was expanded from initial to exhaust pressure, Curtis took what was
the exhaust steam of De Laval's single chamber (which exhaust steam, as we
have seen, had additional imutilized kinetic power which De Laval failed to
utilize) and by means of inter-chamber nozzles he so treated the steam that it
could be reused in a second nozzle and chamber, and indeed, in successive ones,
with the result that he utilized, in stages, the kinetic energy which De Laval
had lost. It will then be seen that he subdivided the available energy steam,
which De Laval found of non-available speed, into a number of pressure steps
or stages, so that a single nozzle would no longer have to expand the steam
from initial to exhaust pressure, but a series of nozzles could successively
expand it to intermediate stages until it finally dropped to exhaust pressure.
The result of these subdivision stages of pressure reduced the steam velocity
of an impulse turbine to a practical bucket speed instead of attempting, as
De Laval did, to increase his bucket speed to equal high steam speed.
DeLavaPs turbine attained commercial efficiency by reason of his use of a
rotating element which permitted extremely high bucket speed. But Curtis
attained commercial efficiency by such a relatively low bucket speed as required
no special mechanical expedients and thereby secured an economical co-ordina-
tion of steam and bucket speed. But his disclosure was more than the mere
duplication of De Laval's nozzle and chamber. Curtis co-ordinated his own
several pressure stages so as to secure such subdivision of energy between the
chamber stages that while taking the steam in succession and operating with
the same shaft speed the several stages were adapted to give an efficient
abstraction of energy. Thus the several stages, while operating separately in
an efficient manner, also co-ordinately and collectively operated to give over-all
efficiency. This co-ordination involved such a proportioning of the nozzles
and buckets of the several stages that the several stages, while under condi-
tions of fixed shaft speed rotation, were nevertheless adapted to accommodate
the steam flow, at the successively diminished pressure, so that the steam speed
produced by the successive nozzles bore substantially the same relation to the
bucket speed of all other stages. This was more than the mere physical dupli-
cation of De LavaPs single diamber. It is true it involved the thought of the
duplication of chambers, but to that duplication it coupled the inventive, novel,
and practical disclosure of utilizing pressure by stages in impulse turbines,
and so co-ordinating that subdivided pressure in successive chambers that
while using the steam in chamber-succession and operating at the same shaft
speed the several steam stages were adapted to give an efficient abstraction of
energy, and while each individual chamber operated efficiently they all
operated collectively and harmoniously to give a total of over-all efficiency.
** This,'' as was well said by complainants' witness, ** involved such a propor-

228 APPENDIX.

tioning and relation of the nozzles and buckets of the several stages that the
stages were under these conditions of fixed shaft speed rotation, adapted to
acconunodate the steam flow at the successively diminished pressures, and
also so that the steam speed produced by the successive nozzles should bear
substantially the same relation to the bucket speed for each stage as for all
the other stages."

It will thus be seen that Curtis eflSciently and for the first time practically
co-ordinated different pressure stages in an impulse turbine and effected such
a subdivision of energy between the stages that the different chambers, while
utilizing the steam in transit at different stages and on the same shaft, were
by their inter-chamber, jet connection, adapted to secure and utilize an efficient
and complete abstraction. While each, in a sense, operated independently,
yet their co-ordination was such that all worked unitedly to give a satisfactory
total efficiency. The mode of doing so Curtis clearly outlined in his patent:

** The method by which the turbine of my present invention operates
consists in converting the pressure of the fluid into vis viva by stages and
utilizing the vis viva developed at each stage by passing tiie fluid mrough
rotating vanes, the speed of revolution of which is adapted to abstract
substantially all or a large portion of the velocity. In practicing this
method I first convert a definite amount of the initial pressure of the fluid
into vis viva by passing a jet of fluid through a nozzle or passage properly
proportioned to give the desired result, and I deliver the flowing jet to a
movable element of the apparatus consisting of one or more circular
ranges of vanes forming passages through which the jet passes and in
which its direction of flow is changed, so as to extract its velocity wholly
or largely whereby the vis viva developed in the nozzle or passage is wholly
or largely converted into mechanical rotation. The fluid issues from
tiiis nfovkble element into a stationary passage, which is so propor-
tioned as to convert a further definite amount of the pressure remaining
in the fluid into vis viva, and which delivers the fluid in a jet to the second
movable element consisting of one or more circular ranges of vanes, by
which tiie direction of the flow of the jet is changed, and its velocity is
again wholly or largely extracted, whereby the vis viva developed in the
intermediate passage is converted wholly or largely into mechanical power.
The energy of the fluid may be converted into mechanical power in two
or more such steps or stages, but it is essential that the various stages be
so co-ordinated that the flow through the apparatus shall be continuous.
To this end the successive working passages to which the jet is admitted
in the movable elements of the apparatus are enlarged in cross-section and
correspond in size witii the discharging ends of the successive stationary
passages, and in each element in which vis viva is developed provision is
made for carrying the same mass of fluid as is admitted to the flrst nozzle

or passage, having regard to the volume and velocity The velocity

developed and utUized at each stage may be the same, in which case the
speed of the several movable elements will also be the same, or the former
may not be the same, in which case the latter will also vary. The movable
elements may be mounted on the same or different shafts. If they are
mounted on the same shaft but have different rates of motion, their
diameters should be different, so that the speed at the shaft may be the

same The pressure of the fluid jet is not reduced during its passage

through the utilizing vanes, except to the extent necessary to supply what
may be called the * f rictional consumption of energy ' in the passage
through the vanes. The passage must be enlarged in proportion thereto.
.... K is a pipe or conduit leading from the steam boiler or other source

APPENDIX, 229

for supplying the fluid under pressure. This pipe terminates in a nozzle
L which may have diverging sides, as in Figure 1, or parallel sides, as in
Figure 2/'

Practical working directions are also given :

** For purposes of illustration we will assume that the apparatus of
Figure 1 is designed to work between a boiler pressure of 150 pounds and
an exhaust pressure of tw^o poimds, these pressures being absolute and not
by gage (tnis exhaust pressure corresponding to al^ut 26 inches of
vacuum). The pressures existing at the discharging ends of the nozzle
L and of the nozzles of the intermediate stationary passages M, N, and O,
will be such as to develop practically equal velocities at the delivery end
of each of these nozzles, this velocity being, roughly, 1700 feet per second.
The apparatus of Figure 2 is intended to represent a non-condensing
turbine, operating bet^^een a boiler pressure of 150 pounds (absolute),
and an atmospheric exhaust, say 16 pounds pressure. In this case the
pressures at the discharge ends of the nozzle L and of the nozzles of the
intermediate stationary passages M, N, and O will likewise be such as to
develop practically equal velocities at each nozzle, and in this case such
velocity will be roughly 1300 feet per second.'*

It will thus be seen that the question whether a divergent or non-divergent
expansion nozzle is required depends upon whether or not the velocity for
which it is designed is above or below critical velocity, or what is the same
thing, upon whether the lower pressure into which the steam is delivered at
each stage is less or more than 58 per cent of the higher pressure from which
the steam is delivered. If the velocity desired is less than the critical velocity
the fall in pressure will be to a lower pressure, which is more than 58 per cent
of the higher, and, therefore, a divergent nozzle will not be used as a straight
nozzle will give all the velocity required. On the other hand, if a higher
velocity than the critical is desired, the fall in pressure must be to a point less
than 58 per cent of the higher pressure and a divergent nozzle is needed to
fully convert such fall of pressure into velocity.

A second disclosure of Curtis 's patent was velocity staging or velocity
compounding. Prior to Curtis 's patent it had been suggested that the poten-
tial velocity remaining in the exhaust steam from DeLavaPs turbine should
be utilized by a second or third application of the jet to a second or third set
of vanes. From this it is contended that Curtis 's velocity compounding is
simply the multiplication of De LavaPs single vanes. Had this been all Curtis
did we may assume that De Laval or other inventors would have so duplicated.
But the very fact they did not is in itself proof that more than mere duplica-
tion was involved in the intervening yeai-s between De Laval and Curtis. In
point of fact no one prior to Curtis showed how such duplication could be
practically done and with good reason, for we now know that, in the absence
of since discovered knowledge in the steam art, no such duplication was pos-
sible. At that time the knowledge of steam friction and rotation losses was
not such as to make possible the utilization of succeeding velocity stages in
impulse turbines. Indeed, before the possibility of such utilization could
exist, a knowledge of steam friction and rotation was a sine qua non to deter-
mining the proper design of buckets of succeeding rows; and, in fact, the
angles of the gtdde vane edges and also the angles of the bucket of a second
and succeeding rows depend on the velocity of the steam at such point.

230 APPENDIX.

Undoubtedly the proofs show that in 1895, Sosnowski, in a paper on
De Lavars turbine read before the Civil Engineering Society of France, sug-
gested the velocity compounding of that turbine. He stated that the steam
on leaving the first row of buckets could be re-directed against the second
row and in this way steam velocity, that would otherwise be lost, could be
utilized. But neither he nor any other engineer showed how this could be
practically accomplished. Public statement of such desiderata, in the absence
of any solution, evidences the need of invention to answer it. And such inven-
tive act had to await further knowledge in the steam art before it had any
possible working basis. As said by one of complainants' witnesses:

** It was not until after the experiments of Odell in 1904, described
in Stodola's Steam Turbine, page 134, and experiments by Stodola (see
page 130) that the losses due to steam friction and the rotation losses were
sufficiently determined to enable a correct design of a single pressure stage

impulse tiirbine having two or more velocity ^ges No practical use

was made of the velocity-compounding suggestion nor could have been
made, until it was made by Curtis, when his pressure-compounding scheme
made velocity compoimding feasible.''

And by another,

" This plan of repeated application of a steam jet to moving vanes,
commonly called * velocity compounding,' is now known to have been
always impracticable when applied to a jet embodying kinetically the
entire energy of the steam because of the very great friction losses involved
when steam speeds were so very high. When these steam speeds had been
suitably reduced by pressure staging, however, as now provided in the
Curtis specification, the velocity compounding of an impulse turbine
became, for the first time, profitable and practicable."

Indeed, the seemingly inevitable loss of residuary potential velocity in
the exhaust steam of a single impulse turbine was recognized by De Laval
himself, for in an article by Olssen, published in the Swedish Engineering
Journal, Teknisk Tids Krift, of February 11, 1893, and republished in a pam-
phlet distributed by De Laval at the Chicago Exhibition, is described the
function of an ejector which partially exhausted the pressure within the cham-
ber whereby supposed additional efficiency of the turbine was thought to
result. Simply stated, the velocity compounding of Curtis 's patent consists
in venting the force of the steam jet on two or more successive sets of movable
vanes in a single pressure-staged chamber, and Curtis for the first time
instructed the art how, by means of suitably designed movable and stationary
vanes, a jet could be efficiently carromed and recarromed from successive
movable to stationary vanes in such a chamber. Why the effect of this double
or friple division of a jet upon two or three vanes in a pressure-staged chamber
is such as to make three such velocity stagings reduce periphery speeds as much
as nine pressure staged chambers is to us inexplicable, but such is its really
wonderful effect. Velocity compoimding is thus set forth in the patent :

" I deliver the flowing jet to a movable element of the apparatus con-
sisting of one or more circular ranges of vanes forming passages through
which the jet passes and in which its direction of flow is changed, so as
to extract its velocity wholly or largely, whereby the vis viva developed in
the nozzle or passage is wholly or largely converted into mechanical
rotation. The fluid issues from this movable element into a stationary

APPENDIX, 231

passage, which is so propoi-tioned as to convert a fmiher definite amount
of the pressui*e remaining in the fluid into vis viva, and which delivers
the fluid in a jet to the second movable element consisting of one or more
circular ranges of vanes, by which the direction of the flow of the jet is
changed, and its velocity is again wholly or largely extracted, whereby
the vis viva developed in the intermediate passages is converted wholly or
largely into mechanical power. The energj' of ttie fluid may be converted
into mechanical power in two or more such steps or stages, but it is
essential that the various stages be so co-ordinated that the flow through
the apparatus shall be continuous."

This brings us to the question, was Curtis ^s disclosure of thus pressure
staging an impulse turbine alone or the combining of such pressure staging
with velocity compoimding inventive? After a patient and thorough study
of this record, we are satisfied it was. When Curtis started the work which
eventuated in this patent the steam turbine problem was involved in com-
plexity and uncertainty. The pioneer work of Parsons and De Laval was
based on machines wholly unlike in basic principle of operation and this dis-
similarity rather tended to confuse and mislead those who sought improve-
ment in lines common to both. Indeed, as noted in the earlier part of this
opinion and justly stated by complainants' witness:

" . . . . the successes and distinctive spheres of these two leaders
tended to lead away from the path Curtis followed of blending the advan-
tages and avoiding the disadvantages of both. Eadi of these inventors —
and those who followed the path of each would be led in the same way —
had had too great success along his own line to think of abandoning or
fundamentally modifying or departing from the basic principle that had
led him to success. Instead, each naturally went ahead to perfect the
details devised to overcome the defects developed by the application of
his basic principle — De Laval in devising reducing gear, flexible shaft, and
the reduction of speed by mass-compounding his working fluid; Parsons
turning to his balance piston against axial thrust in place of the median-
steam introduction of his original disclosure and striving to minimize
clearance steam escapes. Designers, less original than these tiu*bine
leaders, naturally also looked at the art from the standpoint of one or the
other of these men and worked for a future along these lines.''

The situation is in our judgment most fairly smnmarized by a mtness
of complainants, who says:

*' The laws of steam action in these turbines was but dimly perceived
■except that speeds must be kept down ; and since, in the entire history

of steam motors up to that date, the desideratum had always been to get
rotative speeds up, past experience serv^ed only to puzzle rather than to
help. The state of public opinion at that date may be had by a glance
over the pages of the papers by Mr. K. Sosnowski, civil engineer, pre-
sented to the iSocietc D'Encom'agement Pour L'Industrie Nationale in
J 896 (revised and published in book fomi in 1897 imder the title * Roues
et Turbines a Vapeur '), which was generally accepted by later writers
as historically sound. Almost every conceivable combination and arrange-
ment had been proposed or tried, but more or less blindly, and with
imiversal futility. All that was plain, as the result of this, was that
departure from Parsons or De Laval toward any novel principle of action
must call for a thorough re-design of the entire machine and a departure
into unknown territory. "

232 APPENDIX.

As we have seen. Parsons and De Laval were pioneers in their several
spheres, but they did not block the way to further advance. Curtis's advance
consisted in giving to the art a device which, by its construction and mode
of operation, avoided difficulties individually incident to both Parsons and
De Laval's turbines. Compared with Parsons he eliminated clearances and
avoided axial thrusts; compared with De Laval he avoided the wasteful
method of creating high speed initially and neutralizing it by reducing gear,
but obtaining low speed initially, he extracted the whole working force of the
steam. As compared with both he mechanically compacted his working parts
and space into smaller compass and in his turbine disclosed a principle appU-
cable, as Parsons was, to turbines of large size, and applicable, as De Laval's
was, to those of small size. He gave the art a type of turbine which efficiently
and for the first time showed working results different from any theretofore
disclosed in the turbine art. We are clear in the conclusion that his device
was not the work of a mere constructor in his art, but that of a reconstructor,
who brought originality of conception, unlooked for and imsuspected lines
of action and OTeative novelty in the disclosures he made. These features,
coupled with his departure from beaten paths, and the novel and useful results
he obtained by methods not before known, evidence the inventive nature of
his work. We have no hesitation in holding his patent valid imless antici-
pated. In the prior ail we limit ourselves to the measure of the scope of
alleged anticipation contended for by one of respondent's experts, who said:
** The true state of the art in 1896 is that represented by Morehouse, Harthan,
Mortier, and De Laval, plus the same developed knowledge on which Curtis
relies." Now there is no proof that any of these produced a practical efficient
turbine, and there is a statement by the same witness, ** I do not know that
the machines of Harthan, Toumaire, and Morehouse were ever put into prac-
tical use, nor do I know if at their respective dates the engineering knowledge
as to steam flow through nozzles, etc., was adequate to permit successful
practical use of these machines," Avhich virtually admits they did not. A
British patent. No. 144 of 1858, followed by an American one, was granted
to the Harthans for a motive power engine to be worked either by air or steam,
** whereby the expansive and reactive force of the propelling medimn
is brought into play." A study of this patent shows that the Harthans did
not purport to disclose any new principle of operation, but their device was
based on the form of their buckets and the general arrangement of their
machinery. If those features involved any new principle of operation the
patentees neither knew nor claimed it, or indeed, anything save their peculiar
bucket form, for they say:

** We are aware that rotary engines, consisting of wheels having a
number of projections formed or fitted into their peripheries and actuated
by the impingement of steam or air against such x)eripheral projections
or chambera, have long been known in this country, and therefore we lay
no claim to the principle of such arrangement .... but what we consider
to be novel and original and therefore claim .... is, firstly, the system
or mode of obtaining motive power by causing steam or air to impinge
upon a series of chambers with curved bottoms arranged round a wheel,
at or near the periphery thereof, as herein described."

APPENDIX. 233

A study of the patent shows that these curved bottom chambers, which
the Harthans regarded as peculiar to their wheel, are particularly described.
Their device is described as made:

" . . . . with a number of peculiarly constructed projections forming
chambers somewhat similar to the buckets of an overshot water wheel.
.... The bottom or lower part of each chamber is made of a curved or
nearly semicircular form, the curve commencing immediately at one side
of the mouth, and terminating in the same lateral line, so as to extend
from side to side of the chamber, or in the direction of the axis of the
wheel .... a jet or jets of steam is or are brought to play into these spaces
or chambers entering therein nearly at a tangent to the periphery of the

wheel The steam or air on issuing from the jet enters the spaces or

chambers on one side, impinges against and passes over surfaces of the
curved bottoms thereof, and issues out on the other side of the spaces
nearly in an opposite direction to that at which it entered, thus imparting
its force to the wheel by pressure and reaction and causing it to revolve. * '

These and other references thereto show that the operative element w^hich
characterized the Harthan turbine was the curved bottom of their chamber,
and that all other features to which allusion is made were mere incidents
thereto. The device left no impress on the art during the years that passed
before Parsons first utilized the turbine, and we are, therefore, warranted in
accepting as an explanation of its non-use, the statement of one of com-
plainants' expert witnesses, who says:

** As to liis simple impulse wheel, it is now common knowledge, and
in Harthan 's day was technical knowledge, that a jet from a converging
nozzle could not convert into kinetic form more than about 15 per cent
of the energy potential in the steam. Hence the net efficiency of a wheel
driven thereby could not exceed 10 or 12 per cent, a quite useless figure.''

It is contended, however, that Harthan 's disclosed velocity compounding
in their wheel, and in support thereof attention is called to their language :

** Figm'e 6 represents a detail of a third modification, where w^e pro-
pose to employ two wheels CC, each precisely similar to the w^heel in the
last described arrangement, both of such wheels being fast on one shaft D.
A space is left between the contiguous falls of these wheels for the recep-
tion of four or more returning chambers d, d, the bottom of which are
curved in a direction opposite to that of the bottoms of the chambers

c, c, in the w- heels The jet on being first introduced impinges against

the curved bottoms of the chambers in the wheel c', and is then diverted
against the fixed chambers d, d, Avhence it is again diverted onto the curved
bottoms of the cham])ei's in the second wheel c, and finally passes off by
the escape pipe in the manner described.''

To the lay mind and apart from all expert speculation in the matter it
would seem that when Harthan 's single impulse wheel was not practically
efficient, a mere suggestion of employing two wheels, ** each precisely similar
to the wheel in the last described arrangement," would tend rather to dupli-
cate than eliminate the objections to the one. But laying aside this simple
lay view and taking up the speculative one, it seems to us that the very most
that may be said of Harthan 's is the statement of Stodola in the 1910 edition
of *' Die Dampf turburen, " that the ** Predecessor of Curtis are John and
Ezra Harthan in their English patent. No. 144 of 1858 (Figure ()9o>. The

234 APPENDIX.

use of two velocity stages in an impulse turbine is here for the first time clearly
proposed, the enlarging of the cross-section, and, moreover, even the di^isions
of the drops in pressure are particularized/' But assuming they were prede-
cessors, wherein did they precede Curtis? Stodola says they suggested for
the first time the use of two velocity stages in an impulse turbine. But there
are some inventions the inventive element of which consists in the conception
of the novel abstract idea as contrasted with others wherein the invention con-
sists in the practical means of applying what had theretofore been but a mere
abstract idea. In the former the conception of the abstract idea necessarily
involves the details of utilizing it. In the latter it does not. Here, as Stodola
says, the Harthans for the firat time may have clearly proposed two velocity
stages in an impulse turbine, but coupled with the proposal were no practical,
efficient means of obtaining such stages, and tested by the common sense
truism, by their fruits ye shall know them, we are unable to find in the dis-
closures of this patent, or by any residts flowing therefrom, anything to
minimize the value of the work of such men as Parsons, De Laval, and Curtis,
who entered a field that, inventively, was then barren. Nor does it serv^e to
minimize the work of these men to say there was no call for high-speed tur-
bines and, therefore, the quiescence of the art from Harthan to Parsons
has no significance. For it will be observed, as the current of events narrated
above shows, that when the call for turbines came Parsons had years and
years of patient pioneer work in the field of reaction turbines following even
the grant of his patent, before it was commercially and successfully applied,
while in the impulse field De Laval's work was, as we have seen, so revolu-
tionary that his disclosure was regarded as an impossibility by the patent
authorities. In the face of the expenditure of such subsequent study and
effort by engineers of all coimtries, to now contend that the vital featiu'es of
pressure staging and velocity compoimding were anticipated, disclosed, and
utilized by Harthan in a fruitless patent wherein the only characteristic claim
was for curved bottom buckets, is a contention to which we cannot assent. On
the contrary, we adopt, without here discussing the reasoning and illustration
thereto warranting, the contention and conclusions of a witness for com-
plainants, who says:

** As to Harthan 's velocity compounded wheel, even if it were
equipped with a De Laval nozzle, it could not be passably efficient when
built according to Harthan 's instructions. Harthan specifies that the two
wheels, and the intermediate guides as well, are to be alike ; whereas it was
well known even in 1858 that abstraction of vis viva in successive stages
can be accomplished efficiently only when the first, second, and third sets

of vanes are markedly dissimilar As to Harthan 's list of possible

modifications, he plainly classes them of quite incidental value. All but
the last we now know to be trivial in their import. As to the last sugges-
tion, for the connection by piping of a niunber of separate casings in each
of which rotates an impulse wheel, through which casings the steam passes
in series from boiler to condenser, . . . . w^e now know that such a series
of turbines would be practically inoperative. Its adjustments of relative
pressures and speeds would be such unstable equilibrium that the slightest
of the ordinary variations in actual service would put it out of commis-
sion In contrast with this, Curtis 's invention, as disclosed in

patent 566,969, lay in first defining the problem in hand as the simul-

APPENDIX. 235

taneous reduction of wheel speeds, steam leakage, and delicacy of struc-
ture, and then in describing the combination of pressure staging with
impulse action, aided by velocity compounding as the means thereto.''

We next turn to the American patent to Morehouse, No. 195,630, of 1877,
for which same device his British patent of 1876 was granted, which is alleged
to anticipate the pressure staging of Curtis. There is no statement in the
patent as to whether Morehouse's principle of operation was to be applied
to reaction or impulse turbines, and whether he made use of the pressm^e or
velocity of the steam. There is no reference anvwhere to any jet or impulsive
action of steam. On the contrary, that his turbine was operated by pressure
difference, rather than by velocity, is indicated where he says :

** The openings in the dividing plates between the several compart-
ments are arranged so that the driving fluid, in its passage through them,
operates upon the vanes or buckets upon the turbine wheel in the com-
partment into which it is passing, and the turbine wheel is thus with a
force proportioned to the difference in pressure of the driving ftiid in the
two compartments. By the novel arrangement described, the difference of
pressure between each two adjoining compartments is comparatively small
and it is thus possible to actuate the turbine wheels and the driving shaft
at a moderate speed, which is impracticable where high-pressure steam
is used to drive a single turbine."

He further adds:

** If steam of 96 pounds per square inch is admitted through the inlet
pipe h, the openings in the first dividing plate are of such area that its
pressure is reduced to 92 pounds in the second compartment; and in its
passage it drives the first turbine wheel with an effective pressure of four
pounds per square inch only. In the same way it passes through all the
other compartments in succession, its pressure being reduced four poimds
per square inch in each, but its volume being increased proportionately
by expansion."

In the British patent Morehouse states the drop in pressure is one not
only to the area openings, but as well to the compartment capacity, saying:
** The openings being of such area and the compartments of such relative
capacity, that the steam expands to a calculated extent in its passage." But
not only does this strongly suggest that Morehouse's was a reaction turbine,
but in his British patent he refers to the description he has given in language
which can be predicated on a reaction, but not on an impulse turbine, which,
as we have seen, to be efl&cient cannot travel at over half the speed of the
impelling steam. That language is: ** It is not necessary that the turbine
wheels should be made to travel at the same speed as the steam which actuates
them, as assumed in the foregoing description." It is true the language
following: ** They may be made to travel at a less speed than that of the
steam, and very good results may be obtained when the velocity of the wheels
is half that of the steam," might be applied to an impulse turbine, as contended
by respondent's experts, but as it is undoubtedly referable as well to the
reaction turbine of his '* foregoing description," we think it would be a
strained construction to apply the language in its juxtaposition to any other
type of tm^bines, and Stodola, page 83, says : ' * Morehouse ( Figures 169 and
170) coimts only upon pressure stages." We, therefore, conclude that what-
ever principle of operation Morehouse had in view, he threw no light on

236 APPENDIX.

applying it to an impulse turbine. And this conclusion as to impulse turbines
becomes more significant when the Morehouse patent is considered with special
reference to De Laval's type of impulse turbine, of which type the Curtis
is, as we have seen, an improvement. For it must be conceded that whatever
principle of pressure staging Morehouse disclosed, anything he disclosed was
not applicable to the hi^Hspeed impulse tiu*bine which De Laval produced
by his nozzles where there is no pressure difference at the inlet and outlet
ends of the moving vanes, for, prior to De Laval, as we have seen, no one (and
of course, Morehouse) dealt ^ith the then unknown condition of a pressure
drop created solely in the nozzles. And, indeed, Ctentsch, who in his Dampf-
turbiu-en (an authority quoted by one of the respondent's witnesses as " a weD-
known member of the German Patent OflSce and a very hi^ authority on
steam turbines ")• while classifying Morehouse's turbine as an impulse one,
wholly disassociated him and other designers from the De Laval type, saying :

* * The steam which expands outside the nozzles, and which in the free
jet wheels is mostly made to perform work during the period of expan-
sion, is able to convert onlv a small portion of its pressure energy into
current energy, so that the\vorking of the velocity turbines hitherto dis-
cussed has not given a satisfactory economical result A better state

of things was produced for the first time by the invention of De Laval."

Finding, then, as we do, that the disclosures of the Morehouse patent had
no helpful bearing or practical effect on the impulse turbine art, and sup-
ported in that conclusion by the fact that its vagueness is such that fair-minded
witnesses in this record greatly differ as to what its disclosures really are, we
are not warranted in attributing to it any effect in the way of vitiating, or even
minimizing, the work of Curtis. We pass on to the Mortier article.

In 1890, Rateau, a French savant, read before the Society of Mineral
Industries of France two papers on the Parsons turbine, which had been
lately exhibited at the Paris Exposition. In his first paper, Rateau discussed
that turbine, stating its advantages and disadvantages. Several members
expressed their views upon it, following whom M. Mortier stated ** that this
form of motor utilizes the complete expansion of steam," whereupon the presi-
dent inquired, ** What advantage is gained by using the steam in the form of
velocity instead of using it in the form of pressiu^ef " Mortier 's subsequent
remarks were evidently prepared with reference to this question, and in order
to gather their significance it is important to determine what the president's
question raised and how it was understood by those present, and how it was
acted upon. That it meant a comparison of the worth of a reciprocating
engine and some turbine is clear. But what tiu-bine? Respondent contends
it covered impulse turbines. We cannot accede to this view. The question
was raised by the president, not by Mortier, and as we have seen was called
forth by the assertion of Mortier, who was apparently completely satisfied with
the Parsons turbine: ** This motor utilizes the complete expansion of steam."
Mortier was seeking or suggesting no other form or type of turbine and the
president, then, in substance, put the question as one between the Parsons
turbine and a reciprocating engine. Certainly Rateau so tmderstood the
question, for he answers ** that he intends to treat this question and to com-

APPENDIX. 237

plete his communication (which was based wholly on the Paraons turbine)
at a future meeting ''; and the society so understood, for its minutes state:

'' Order of the day for the meeting of April 12, 1890: The Parsons
Steam Turbine/'

Moreover, Bateau's subsequent paper was based on the question between
Pareons and the reciprocating engine, opening with the statement :

I wish to-day to enter upon some considerations, theoretical for
the most part, which will permit me to compare this new kind of motor
with ordinary steam engines and to arrive at an estimate as to the prob-
able future in store for it/'

As if to emphasize and limit himself to this single issue, he announces his
satisfaction with the Parsons machine, saying : * * New types will imdoubtedly
succeed one another, and there is reason to expect within a short time the com-
plete solution of the question already fitly answered by the Parsons system,''
and disposed of another type (Dow's) lately introduced, which he estimates
as "... . inferior, from various points of view% to that of M. Parsons," and
of which '*.... in its present condition the system would not be of a nature
to be widely introduced in practical industry." He then takes up the Parsons
as the turbine basis of comparison with a reciprocating engine and states his
conclusions which need not bo quoted.

The minutes then state, *' Continuing the preceding communication,
M. Mortier gives the following infonnation on the same subject." Without
entering upon a discussion of Moriier's statements and calculations it sufl&ces
to say that to us the inherent proofs of the proceedings show that they are
directed to the Parsons type, which, as we have seen, was a reaction turbine.
There was nothing in the subject before the society to suggest the introduction
or discussion of impulse turbines. That meeting was discussing a particular
reaction turbine; it was practical and efficient; and they had seen it operate.
It was the contrast of this practical device wdth steam engine practice the
society was discussing. There was no necessity for discussing hnpulse tur-
bines, for no one had then produced one that was practical and efficient. And,
as we have seen, no engineering basis of fact existed prior to De Laval for any
speculation as to the future of the impulse turbine. If the striking effects of
pressure staging and velocity compounding impulse turbines, which after-
wards gave them efficient working value, w^ere then realized and disclosed by
M. Mortier's paper, he never claimed them in his paper; his subsequent acts
were in conflict with such a claim ; and the engineering world ignorantly suffered
years to pass and misguided efforts, in other directions, to be made in the face
of such disclosures. Indeed, if Mortier's address be assinned to apply to
impulse turbines and to disclose Curtis 's mode of overcoming their failings,
Mortier's subsequent acts are inconsistent with such assumption. When he
subsequently took up the subject of minimizing the steam speed it was not, as
shown by his two Frencli patents of 1894 and 1895, on the principle of oper-
ation now alleged to have been disclosed by him, to wit, the principle of
eliminating such speed, but on the principle of controlling such speed by
mixing live steam with hot water or exhaust steam. This system, which as now
known resulted in a loss of from one-half to three-quarters of available steam

238 APPENDIX.

energy, shows that Mortier, instead of anticipating Curtis in his disclosui-e,
followed in the lead of those inventors of whom Stodola said :

** The majority of the older patents showed lack of knowledge of the
laws of steam flow. One idea especially led inventors on in spite of con-
stant failure: to decrease the velocity of the steam by mixing if with fluids
or gases/'

We next turn to the question of infringement. The disclosures of Curtis 's
patent, as we have seen, consisted, broadly stated, of pressure staging an
impulse turbine, the velocity compounding thereof and the abstraction, at
each passage of the steam, substantially all or the principal part of the vis viva
developed at the preceding stage. Without discussing the proofs in detail,
we may say we find these features in the respondent's turbines. The proofs
show the proposals made by them to the government for equipping certain
vessels with turbines and a guarantee that certain results will be obtained. We
are warranted therefrom in assuming the respondents meant to comply with
their representations and contract guarantees, and in the absence of any proof
by them tending to give the court light on exactly what form of turbine they
are constructing, we are, under the authorities, Peifer vs. Brown, 85 Fed. Rep.
780; Celluloid Co. vs. Arlington Co., 85 Fed. Rep. 449, justified in resting on
the proofs of complainants before us. These show that the principle of oper-
ation of respondents' turbine is distinctively impulse, that it is multi-pressure-
staged having 32 pressure stages, 12 stages having two velocity rows each and
20 stages one row each. On the same shaft is mounted also a reversing multi-
pressure-staged turbine having three pressure stages with two velocity rows
each and the rest with one. We agree with the deductions drawn by com-
plainants, based on calculations on data as to bucket speed and steam speed
furnished by complainants' witnesses, that the abstraction of vis viva by
respondent's turbines is substantially and practically complete, the unused
velocity amoimting to 2.29 per cent the energy and this conclusion is con-
firmed by the standard of efficiency guaranteed to the government by the
respondent under the designed full speed conditions. That when operated
under other conditions such turbines might abstract lesser amounts of vis viva
does not relieve the turbine of its infringing character. Being designedly
made capable of infringement, its capacity to infringe warrants the conclusion
that it does infringe. It is contended, however, that infringement of the
Curtis patent is not established unless there is an absolute and total abstraction
of vis viva. We find no warrant for this contention in the specification or
claims of that patent and we find no ground in reason or thermodynamic
practice for such extreme contention. The economies of fuel, power, and
indeed all motive mechanism, are necessarily only approximately perfect.
Waste, loss of motion, and power are incident to all mechanical, thermal, and
motor operations, and the effort is to reach substantial, practical results rather
than absolute theoretical ones. And such substantial abstraction was the
measure Curtis disclosed in his specification.

*' My object is to develop mechanical power from steam or other
elastic fluid under pressure by utilizing a large proportion of its vis viva

in a turbine, whose speed of rotation shall be low I deliver the

flowing jet to a movable element of the apparatus consisting of one or more

APPENDIX, 239

circular ranges of vanes forming passages through which the jet passes
and in which the direction of flow is changed, so as to extract its velocity
wholly or largely whereby the vis viva developed in nozzle or passage is
wholly or largely converted into mechanical rotation/^

And the same thing is embodied in several claims in the words :

** Said vanes being adapted to abstract at each passage there through
substantially all or the principal portion of the vis viva developed at the
preceding stage/'

In the same way we find no warrant in the patent for restricting the
nozzles or passageways to the expansion pipe. We have already pointed out
earlier in tJiis opinion that the patentee stated parallel and diverging nozzles
were alternative constructions. It is contended, however, that Curtis by his
definition of expansion nozzles in another application to which this patent
refers so restricted himself. But the fact is that this definition was not
embodied in that application when the reference was made. Its subsequent
introduction in such former application was for reasons involved in that par-
ticular application, and just principles of construction do not necessitate it
being retroactively applied to a patent which expressly negatived both in speci-
fication and figures any such restricted meaning. The partial peripheral intro-
duction of the steam has been emphasized in complainants' testimony as a
feature of marked advantage in impulse turbines and which distinguished
them from the reaction type. In his specification Curtis lays stress on this
feature as one characteristic of all his passages and as distinguished from
introduction in annular form, saying:

'* It is the design of my present invention, as of the apparatus of my
prior application referred to, to employ at the delivery end of the nozzle
and in the working passages a * jet ' of steam or other elastic fiuid, i. e., a
practically solid stream of fiuid having an oblong foinm in cross-section
whose thickness bears a considerable proportion to its width, so that its
cross-sectional area will be large compared with its perimeter as distin-
guished from an annular film of elastic fiuid whose cross-sectional area
is small compared with its perimeter. By this means the f rictional retarda-
tion is greatly reduced and the efficiency is largely increased.''

It is manifest, therefore, that a turbine which while it delivers *^ a fiuid
jet to a portion of the vanes within the first shell," but not to the succeeding
ones, does not infringe a claim, one of the elements of which is * ' intermediate
passages connecting the different shells together and delivering the fiuid jet
to a portion of the vanes of the different sets in succession." Gaged by these
general conclusions we find that with the exception of the seventh and tenth,
all of the claims charged are infringed.

. We next turn to patent No. 595,435, the first, second, third, and fourth
claims w^hereof are alleged to be infringed. The object of Curtis, as stated
in his application, was *' to produce an elastic turbine operating under condi-
tions of high efficiency in which variations in speed may be effected without
great variations in the efficiency of operation." This he accomplished ** by con-
structing and arranging the fluid passages of the turbine and their connections
in such a way that the elastic fluid may be caused to traverse the movable vanes
a greater or less number in succession." He states, ** the general plan of the
elastic fluid tinrbine being such as is described in patent No. 566,969, issued

240 APPENDIX,

to me September ,1, 1896/' The proofs show that for efficient operation the
vane velocity should be about one-half the velocity of the steam action upon
the vanes where the velocity is abstracted by a single set of vanes, and in like
proportion if the velocity is fractionally abstracted by two or more sets of vanes
velocity compoimded, and consequently, generally speaking, the vane velocity
should be higher the fewer the number of stages into which the pressure drop
is divided. This principle is used by Curtis, whose device, shown in the accom-
panjing Figure 1 (not shown) '^ is so aiTanged that the number of stages
into which tiie pressure drop is divided may be varied according to the rotary
speed at which it is desired the motor should be driven, a less number of stages
being used for higher speeds and a gi'eater nmnber for lower speeds. The
wheels or sets of vanes, which are described as mounted on a common shaft,
are contained in separate casings, and the steam from the boiler is delivered
to the nozzle I, to act upon the vanes in the first casing^ in which the pressure
is lower than in the boiler, and from which the steam passes by passage N
through the nozzle J, in passing through which it expands and acquires
velocity and enters the second casing to act upon the wheel vanes therein, and
so on to the third and fourth casings, from which the fully expanded steam is
delivered through the exhaust passage Q. Provision is made for controlling
the steam passages so that the steam may be made to have a less number of
expansion stages, this provision being shown in the foregoing figure as afforded
by the exhaust passages RST, each provided with a shut-off valve. These
passages respectively commimicate with the connecting passages NOP,
between the successive stages so that, if, for example, the valve and exhaust
passage T is open, the steam will exhaust at the end of the third stage, and the
fourth stage and parts pertaining thereto will be cut out of action. By the
division of the pressure drop into three stages, the velocity of each stage will
be increased as compared with that produced when four stages are used, being
about foui'-sevenths instead of one-half of the velocity due to the total drop.
Similarly, if the valve in the passage S were opened, steam would exhaust at
the end of the second stage and the velocity in the two stages would be about
five-sevenths of that due to the total drop, and if the valve in the passage R
were opened the entire pressure drop would be used at a single stage, giving
a steam velocity and consequently an efficient wheel velocity almost double that
produced when the four stages are used. ' ' It vnil thus be seen that what Curtis
really disclosed is simply taking and equipping with cut-off devices, a multi-
staged turbine of the type of the patent we have already described, and fitting
it with devices whereby different chambers could be operated or by-passed
as desired. The particular means employed by him are embodied in claim six,
which is not charged to be infringed. Assmning, for present purposes, that
such device is patentable and that Curtis is entitled to a monopoly of a specific
device embodying a combination of parts as will control the use of the several
chambers of a turbine, it does not follow that he is entitled to such generic
claims as are here involved and which, if sustained, would give him a monopoly
of all turbines using controllable passages whereby the steam is made to act
upon movable vanes a greater or less number of times in succession. In view
of the recognized practices of steam control and the special character of
Curtis 's device, it would be a perversion of patent law and principles to make

APPENDIX. 241

this control device of his a basis for monopolizing the whole field of steam
passage control by inclusive claims such as are here involved. Accordingly, we
hold these four claims invalid.

It remains to consider another question presented by the record. The
infringement complained of is referred to in paragraph 21 of the bill, which
avers that defendant did, before the beginning of the suit,

**.... offer in writing, accompanied by plans and specifications, to
make for, and to sell to, the United States Government, elastic fluid tur-
bines for propelling ships — or, in other words, for marine propulsion
other than automobile torpedoes — employing and containing the inven-
tions set forth in each and all of the several letters patent ; that the offer
so made by the defendant has been accepted by the United States Govern-
ment ; that the defendant is at present under contract to make such infring-
ing elastic fluid turbines ; that the work of construction of such infringing
tiu-bines is now being proceeded with by said defendant \\ithin the Eastern
District of Pennsylvania, and elsewhere in the United States, for the
purpose of furnishing the same to tlie United States Government under
the said contract ; that all of said acts and doings by the defendant have
been and are without license or allowance, and against the will of your
orators and in violation of their rights ; and that the defendant is threaten-
ing to carry on its aforesaid unlawful acts to a large extent in violation
and infringement of the rights and privileges of your oratore, and to their
gi'eat and irreparable loss and injury," &c., &c.

Accordingly, paragraph 23 prays defendant may be decreed to accoimt
and pay over all such gains and profits as have accrued or may accrue ^* by
reason of any such infringement," and also account for and pay over all
damages sustained or to be sustained ** by the said unlawful acts "; and a per-
petual injunction is prayed to restrain the defendant from '* directly or indi-
rectly making, constructing, using, vending, delivering, working, or putting
into operation or use, or in anywise counterfeiting or imitating, the said several
inventions, or in any elastic fluid turbines made in accordance therewith, or
like or similar to those which the defendant has contracted to make for
the United States Government in infringement of the said several letters
patent," &c.

It is also prayed '* that any elastic fluid turbines or parts thereof infring-
ing any or all of the said several letters patent mentioned, and which may be
in the possession of the defendant, shall be destroyed, or delivered up to yoiu*
orators or an officer of this court to be so destroyed." The bill also prayed
formally for a preliminary injunction, but no motion was made for this relief .
Since the litigation began, the two torpedo-boat destroyers referred to have
been flnished and delivered to the government, and the plaintiffs do not now
ask that the decree shall in anywise be directed against these vessels, or
against the government in respect thereof. The bill contains no averment that
the defendant is building or threatening to build infringing turbines for com-
mercial use ; only certain ships of war are involved in the suit ; and, for reasons
to be briefly stated, we are of opinion that no injunction should now be granted.
We do not agree that the court below should have dismissed the bill for want
of jiu-isdiction. Neither the United States nor one of its officers is a party
defendant, but the suit is brought solely against a private corporation that had
contracted to do certain public work.

242 APPENDIX.

The bill was filed in 1909, and we think there was then no doubt that the
court below had the right to entertain it. It had been much debated, and had
been variously determined, how far an injunction might interfere with the acts
of government officers, who in their official capacity were infringing or were
threatening to infringe the rights of patentees. The Supreme Court had
refused to permit a plaintiff to interfere with property owned by the govern-
ment and in its actual possession, but no such decision had ever been made
concerning property that was stiU in the course of preparation for pubUc use
by a contractor with the government. The facts in Dashiell vs. Grosvenor
(C. C. A.), 66 Fed. 334, present this situation as nearly as any other case, and
it may be worthy of note that the Supreme Court took jurisdiction of that
dispute on the merits, and decided the question of infringement. On the face
of such a bill as is now presented, the controversy is primarily between indi-
viduals, and no reason is perceived why the equitable jurisdiction of a court
does not attach. There may be sufficient reasons of public policy to induce the
refusal of relief by injunction, either at a preliminary stage or after final
hearing ; but this is a separate question, distinct from the principal matters of
dispute, and does not operate retroactively to take away the power of the court
to hear and determine the controversy on its merits. The relief to which a
plaintiff would ordinarily be entitled in a suit between individuals may be
denied in a particular case for special reasons, as it may be denied where no
question of public policy can possibly arise ; but, we repeat, this of itself does
not oust the court of its equitable jurisdiction to hear and decide the suit.

But since the suit was brought, the act of 1910 has been passed, and has
been interpreted by the Supreme Court in the recent case of Crozier vs. Krupp,
224 U. S. 290. This statute, we think, furnishes a practical solution of the
questions arising upon this branch of the case. Even if the plaintiffs did not
disclaim the desire to interfere with the government's possession of the vessels,
there is no longer any ground upon which a final injunction can be properly
rested, even in a suit against a contractor with the government, where the dis-
pute concerns such property as vessels of war. If the United States has
infringed, or shall hereafter infringe, the patents that we have been consider-
ing, the act of 1910 permits the plaintiffs to sue in the Court of Claims.
Crozier vs. Krupp, supra. And if the defendant shall undertake to infringe
hereafter by making offending turbines for commercial use, relief can be
obtained by another suit.

The plaintiffs are entitled to a decree sustaining patent No. 566,969 so
far as indicated in the foregoing opinion, and ordering an account, but an
injimction will be denied. Accordingly, the pro forma decree entered in the
District Court is now reversed, with the costs of this court, and the case is
remanded with instructions to enter a decree in accordance with this opinion.
We leave the question of costs in the District Court to be disposed of by that
tribimal.

INDEX.

PAQB

Absolute temperatores 7

Aetlon of steam In Curtis turbine 89

Adlatatlc expansion 13

AdJusUng block, Curtis turbine 94, 107

Parsons turbine 74

Air ejector, Morison 59

Westlngbouse G7

Air-pump, dry 66

twin 61

Weir dual 69

wet 66

Angle of turn 43

Annulus area, blade 47

Appendix 217

Arem, blade annulus 47

noizle, throat, and exit 21

Ar«u on TB diagram, calculation of 13

Arliona's installation 112

reduction gear 131

turbines 67. 69, 76. 82. 83

AMero 102. 104

Angmenter, Parsons 66

Aulllaries, turbines for 161 to 1S4

Axial How i, 2

Bearings. Curtis turbine 94. 107

Parsons turbine 86

Bent tube condenser 64

Blade annulus area 47

height 47

Blades 41

impulse 41

thickening of 42

no shock 43

30" shock 46

material 41

reaction 46, S3

requirements of 41

securing 47

wing 66

Blake twinplex pump 61

British thermal unit 7

BnckeU 41

Calculation of areas on TB diagram 13

Care and operation of Curtis turbines 211 to 216

Parsons turbines. .193 to 209

Casings, Curtis turbines 96. 102, 106

Parsons turbines 71, SO

Clutch, Metten 134

Combined turbines 113 te 117

Parsons 113

Westlngbouse 114,178

Comparison of work done on PV diagram 49

TE diagram 61

Compounding, pressure velocity 29

velocity diagram 31

TB diagram 33

reaction 34

velocity 28

Condenser, bent tube 64

contraflow 64

Condensing plante 49 to 63

mechanical parts 62

requirements of 62

Conner and Stockton Installation 166

Consumption table, steam 1S9

Converging-diverging nozzles 17

Converging noszles 16

Conversion of work and heat 7

Conyngham's installation 164

lubrication system 192

Critical fall 16

Cruising expansions 76

Cruising turbines, Nevada 104

Parsons ■ 82

Tucker 92

Cummlngs' installation 162

turbines 64, 75, 81

Curtis turbine 89 to 111

action of steam In H

adJusUng block 94, 107

astern 102,104

bearings and adjusting block — 94

bearings, main 94

blading 108

care and operation of 211 to 216

casings 96. 102, 106

cruising. Nevada 104

Tucker 92

.95, 96, 102. 106, 106
110

general description 89

glands, shaft 96. 102. 106

Nevada 91. 92, 104

Ill

pressure stages iOl

rotor 92, 98, 100. 104

shaft glands 96, 102. 106

steam 109

Tucker, 91, 92, 93, 94. 97. 9S, 102, 108

velocity compounding 101

wheels 95. 99, 106

Cusblng installation 169

reduction gear 127

Cycle. Ranklne 13

De Laval turbines 162 to 169

Design, practical considerations of 22

principles of 28

Diagram, pressure velocity compounding 32

reaction compounding, velocity 37

TE .

244

INDEX.

PACE

DUphragmt 95. H, 102, 105, 100

Drain eonneetiont, Curtis turbine 110

Parsons tnrUne 87

Dry air-pump 55

Dry or saturated steam 9

Dummy packing 71, 70

piston 71, 70

Duncan and Parker installation 158

Dynamic twlanee of rotors 88

Efficiency 13

nozsle 18

Ejector, Morison air 58

Westinghonse air 57

Electrical transmission 134

Energy, definition 5

graphic representation of heat 6

heat, conyersion of, to mechanical 1

kinetic 5

potential 5

Entropy, definition 7

of eraporation 10

of steam or water 10

Eraporation, entropy of 10

latent heat of 9

Expansion, limits of, of steam 49

line 19

Expansions, cruising 75

Parsons turbine 66

Failure of vacuum 52

Fall, critical 15

Fdttinger transmitter 136

Friction, nozzle 18

Gain for turbines by increase of vacuum 52

General Electric Ck>mpany'8 turbines 172 to 177

Glands, shaft, Curtis turbine 96, 102, 105

Parsons turbine 73, 81, 83

Graphic representation of heat energy 6

properties of steam . . 10
Guards, oil 187

Heat drop, nozzle 21

latent, of evaporation 9

losses 119

of the liquid above 32'*F 9

regenerated 19

total, of steam 9

conversion of, and work 7

Horse-power 8

Hydraulic transmission 136

Impulse 1, 2

blades 41

thickening of 42

no shock 43

30^ shock 45

pressure staging 26

simple 24

velocity diagram 25, 32

turbine 2. 89 to 111

turbine, simple 3, 24

velocity compounding 28

Increase of racnum, gain for turbines by 52

Installation, Arizona's 142

Conner's 156

Conyngham's 154

Cushing's 159

Duncan's 158

Nevada's 144

Pennsylvania's 146

Perkins' 157

Preston's 148

Utah's 140

Wadsworth's 150

Installations, turbine 139

Joule's equivalent 7

Junctiop wheel 78

Kerr turbines 170 to 171

Kinetic air-pump system 56

energy 5

Kingsbury thrust block 74

Latent heat of evaporation 9

LeBlanc rotary pump 62

Limits of expansion of steam 49

Liquid, heat of the, above 32''F 9

Losses, heat 119

Curtis turbine 120

reaction turbine 119

steam friction 119

Lubricant used for turbines 185

Lubrication 185 to 192

Conjmgham's system of 192

forced 186

gear teeth 190

Nevada's system of 190

requirements of 185

ring 190

theory of 185

turbine 185

Material of blades 41

Mechanical equivalent of B. T. U 7

parts of turbine 1

reduction gear 125

Gushing 127

Nevada 127, 129

Pennsylvania.. 131 to 133

Wadsworth 125

Metten clutch 134

Mixed or combined turbines 113 to 117

Parsons 113

Westinghonse... 114, 178

Morison air ejector 58

Necessity for high vacuua 49

Nevada's installation 144

lubrication system 190

reduction gear 127, 129

tur Dines ••.•.....•.•.>.•••.••• ayx, vz, xw4
New Mexico's turbines Ill

INDEX.

245

PAGE

Nonle area, throat and exit 21

efficiency 18

friction 18

heat drop in 21

steam expansion 18

graphically represented 20

Nozzles 96

conTerging-diverging 17

converging 16

steam 15 to 21

velocity of steam 21

Oil guards 187, 188

Oil supply to thrust bearings 189

Operation, care and, of Curtis turbines. ..211 to 216

Parsons turbines. .193 to 209

Packing, dummy 71, 79

Parsons augmenter 56

turbine 65 to 88

Arizona 67, 69, 75, 82

pressure in 83

adjusting and thrust blocks 74

bearings, main 86

binding strips for blades 85

blading 83

blading, wing 66

care and operation of 193 to 209

casings 71, 80

combined 113

cruising 82

expansions 75

Cummlngs 64, 75, 81

description, general 65

details, general 83

drains 87

dummy packing 71, 79

piston 71, 79

dynamic balance of rotors 88

expansions 66

cruising 75

general description 65

general details 83

glands, shaft 73, 81, 83

Junction wheel 78

mixed or combined 113

packing, dummy 71, 79

piston, dummy 71, 79

propeller thrust 77

rotors 69, 75, 79

shaft glands 73, 81, 83

static balance of rotors 87

steam connections 86

thrust block, Kingsbury 74

thrust blocks 74

Wadsworth 68. 69. 75

wheels 69, 70. 76, 77, 82

wing blading 66

Pennsylvania's installation 146

reduction gear 131 to 133

Perkins* installation 157

Piston, dummy 71, 79

Potential energy 5

Power, definition 8

Principles of design 23

Pressure stages 101

Pressure staging impulse 26

PAGE

Pressure velocity compounding 29

velocity diagram. 32

TE diagram 34

Preston's installation 148

Propeller thrust 77

Properties of steam 9 to 14

Pump, air, dry 56

Weir dual 69

wet 66

Blake twinplex 61

LeBlanc rotary 62

twin 61

Quality during adiabatic expansion 14

of steam 10

Radial flow i

Rankine cycle 13

Reaction i, 4

blades 46

compounding 34

velocity diagram 37

TE diagram 39

turbine, simple 8

velocity diagram 36

Reciprocating engines and turbines compared 123

Reduction gear, mechanical 126

Gushing 127

Nevada 127, 129

Pennsylvania, 131 to 133

Wadsworth 126

Regenerated heat 19

Requirements of blades 41

condensing plants 62

Rotary pump, LeBlanc 62

Rotor, Curtis turbine 92, 98. 100. 104

Parsons turbine 69, 76, 79

Saturated or dry steam 9

Shaft glands, Curtis turbine 96, 102, 106

Parsons turbine 73, 81, 83

Specific volume 13

Speed, propeller 119

turbine 119

Staging, pressure 26, 101

Static balance of rotors 87

Steam, action of 1

connections. Curtis turbine 109

Parsons turbine 86

consumption table 139

entropy of 10

formation of 9

friction losses 119

graphic representation of properties of . . . 10

limits of expansion of 49

line 12

nozzles 15 to 21

passages 15

properties of 9 to 14

quality of 10

saturated or dry 9

specific heat of 10

specific volume of 10

superheated 9

tables 10

wet 9

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "Steam turbines; a treatise covering U.S. naval practice"

See other formats