286 



HYDKAULICS AND ITS APPLICATIONS 



increase with the nozzle opening. The curves (Fig. 128) derived from 

 equation (6) of this article, show the kinetic energy (expressed as horse- 

 power) delivered from pipes of diameters 1*0 and 2 - feet, 1,000 feet long, 



under a head of 200 feet, with different values of the ratio . 



A 



The value 



of /has been taken at '005. In each case the maximum nozzle opening 

 for successful governing is that corresponding to the point E. 1 These 



woo 



900 



800 



0-4 0-5 06 07 



ratio of nozzle Co pipe area. 

 FIG. 128. 



OS 09 



1-0 



curves are worth study as denoting the great increase in available energy 

 with the larger pipes. 



While the above investigation is interesting, it is not usual, in a well- 

 designed pipe line, to come across a case in which the nozzle area is 

 greater than the maximum for successful governing since this would 

 entail a velocity of flow in the main much greater in general than that 

 (3 to 6 feet per second) adopted in practice. 



EXAMPLES. 



(1) Two reservoirs are connected by a pipe 500 yards long. For the 

 first 250 yards its diameter is 4 inches, increasing for the second 250 



1 For a further consideration of this subject see an article by Professor John Goodman in 

 Engineering, November 4, 1904. 



