FRICTION OF GASES FLOWING THROUGH BRICK
FLUES OR MAINS («
BY W. A. MOJAROW
IN the flow of gases beneath an inverted weir, or, as it may be
designated, inverted flow, the stream of gas may or may not fill
the flue or furnace to its full height; practically, it may be said
that in those cases where the stream of gases does not touch the
hearth or bottom of the flue, the depth or vertical thickness of the
inverted stream will be given by the formula developed by M. J.
Yesmann, Professor of Hydraulics at the Polytechnic Institute of
in which Q/ = the volume of gas flowing at the temperature t°;
J3 = the length of crest of the inverted weir, that is, the
width of the furnace or flue;
A — SL coefficient which is not constant and varies from
2.97 to 3.62 according to ht and B.
In order to arrive at the actual movement of the gases it is
necessary to take account of the drop in pressure and, likewise,
of the decrease in velocity which occurs at the different parts of
the furnace or flue.
These losses are caused by:
1. Changes in the direction of flow;
2. Changes in the cross-sectional area of the channel;
3. Friction against the walls of the channel.
Information regarding the first two losses and changes of
(1) Revue de laSoriett russe de M&tallurgie, /, pp. 835-371 (1913}. Extrait
de Revue de Metallurgie, XI bis, p. 320, mai 1914.