﻿Orifices, and Entrainment of Air by the Issuing Jet. 987 



the case and is clearly brought out in fig. 9, which gives 

 the results obtained with channels all ot' the same diameter 

 but of different lengths. The effect is much less marked 

 in the case of the longer channel 5 C than in the case of 

 the shorter channel 5 B or 5 A. 



The absence of the effect at the lower pressures is 

 attributable to motion of the gas at such low pressures being 





ORIFICE LENGTH 



(CM) 

 5A 0-2789 

 5B 0-6731 A 

 5C 0-8788 & 









• 









^o 5C 













ScMfr^ 





5bV 







Fig. 9. 















5 10 15 20 



PRESSURE (CMS OF WATER) 



25 



in general so slow that little initial unstable turbulence is 

 impressed upon the stream, and any such turbulence, if 

 produced, is damped out before emergence of the jet from 

 the orifice. At the higher range pressures at which the 

 effect is absent, the passage of the air into the channel 

 approximates to stream-line motion, the air within the 

 reservoir immediately adjacent to the disk being practically 

 stagnant, so that little turbulence is produced by a sudden 



3 S 2 



