116 



HYDRAULICS AND ITS APPLICATIONS 



the following values of C v , for tubes having a length equal to about three 

 diameters : 



The value of C v was found to vary with the length of the tube approxi- 

 mately as follows : 



If suffixes ( ) and ( 2 ) refer to outlet and to vena contracts, since we have 



Fift. 63. 



no loss of head from the surface to the section at ( 2 ) we get 



Again, since the only loss of energy between section ( 2 ) and the 

 outlet, neglecting friction, is that due to the enlargement of section from 

 a f to a, i.e., 



