COMPOUND PIPES AND PASSAGES 



The corresponding expression for circular pipes is 



loss = 



91 



(2) 



Differentiating these expressions with respect to 0, the value of and 

 hence of b 3 or ?' 3 , giving minimum loss of head, may be obtained. As, 

 however, K varies with 0, the resulting expression becomes extremely 

 cumbersome, and the best value is more easily obtained by trial of a few 

 values of 6 and the corresponding values of K. Handled in this way a 

 solution is readily obtained. 



The following table shows values of 6 giving minimum loss of head in 

 such a pipe, along with the corresponding loss of head in the pipe, and 

 in a straight taper pipe of the same length and with the same initial 

 and final areas. 



By this method of construction the loss may be reduced in favourable 

 circumstances to about 90 per cent, (in rectangular pipes) and to about 



