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Full text of "The Flow Of Gases In Furnaces"

40

APPLICATION OF THE LAWS OF HYDRAULICS

VII. THE   APPLICATION   TO   HOT   GASES   OF   THE   THEORY   OF
HYDRAULIC  FLOW   OVER  THICK-CRESTED   WEIRS.

In a large reservoir from which there is a flow over a weir of
Q cu m of water per second there will be established at a constant
height H above the sill of the weir, a water surface which supplies
the hydraulic gradient necessary for the flow (Fig. 24). The



i i

FIG. 24.

depth of the water flowing over the weir will be determined by the
formula:

There is also the formula

Q = 0.356 V2gH*,

from which

CD)

in which b signifies the length of the weir.

This formula makes possible the determination of the depth
of the channel connecting two basins of water, and applies equally

to  the   depth   of  all  streams
whose  bed   presents  a  grade
sufficient to compensate for the
inevitable friction losses of flow.
Each reverberatory furnace
having a horizontal roof forms
the bed of an inverted stream,
FIG. 25.                       in which there flows, not water,

but hot gases (Fig. 25). Re-
verberatory furnaces, in order that they may function properly,
must be so designed as to take account of the following facts:

All of the material which is to be reheated in the furnace is
placed upon its hearth. Much heat will be lost in the reheating
of this material, as well as by radiation from the walls. The

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