JETS FKOM NEEDLE-NOZZLE 



459 



AET. 126. JETS FROM NEEDLE-NOZZLE. 



The presence of the central needle in a nozzle provided with needle 

 regulation causes a reduction in the velocity of the central filament, 





and to this extent tends to reduce the efficiency of the jet. Fig. 208 

 shows the velocity obtained at different points in the cross section of 

 a jet obtained respectively from a plain conical nozzle, a ring nozzle 



