LOSS OF HEAD IN TAPER PIPES 



85 



From these it appears that as is diminished from 180 the loss increases, 

 attains a maximum value for some value of 6 in the neighbourhood of 65, 

 and afterwards diminishes rapidly with until is about 5 30'. This 

 value gives a minimum loss of approximately 13'5 per cent. Any further 

 diminution in is accompanied by an increased loss owing to the large 

 value of the wall friction in pipes of the comparatively great length 

 accompanying such small values of 0. The value of giving rise to the 



0-5 



25 



1-0 1-5 2-0 



A ngle between diverging sides of pipe. 



FIG. 41. Loss of Head in Circular Taper Pipes. 



same loss as is experienced with a sudden change of section, varies from 

 41 to 60, being slightly greater for a given area-ratio the larger the 

 pipes, and, for a given mean diameter, increasing in an irregular manner 

 with the area-ratio. Its mean value over the range of ratios considered 

 is approximately 50, and where, in the design of hydraulic machinery, it 

 is necessary for this value to be exceeded, a sudden enlargement of section 

 gives a more efficient transformation of energy than does a uniformly 

 tapering pipe. For values of between 7'5 and 35 the loss may be 

 expressed with a fair degree of accuracy by the relationships 



loss = '01 10 1 ' 22 



feet, where is in degrees, 



