Mizuki Kito

Jet Flow from Resonance Nozzle and Flow Control by Notched Nozzle

The jet flow from an orifice nozzle shows a particular velocity profile with a large velocity gradient at the edge of the jet. Setting an orifice nozzle, second one, with a resonance room just after the first orifice nozzle the jet causes resonance phenomena and the resonance frequency depends on the jet velocity and the volume of resonance room. In this study, a notched nozzle was used as the second one to enhance the flow disturbance or fluctuation, and the effects of the notched nozzle on the mean and fluctuating velocities and the mixing or diffusion characteristics of the jet itself and with the surroundings were examined experimentally using a hot wire measurements. As a result, it was made clear that under a same operation power the flow rate near the nozzle exit of a notched resonance jet is larger than those of an orifice and resonance jets, for example, at x/d = 0.2 (x: distance from the nozzle exit to the downstream, d: nozzle diameter) it is about 2.5 and 1.3 times of theirs, respectively, and others.

Effects of nozzle contraction ratio on orifice free jet flow

The effects of the contraction area ratio CR of orifice nozzle on the flow characteristics of the free jet issued from the nozzle are examined. The large vortex structure of submerged orifice water jet is visualized by tracer method and examined the effects of CR on it. The mean and fluctuating velocities of orifice air jet are measured by a single probe and hot-wire anemometry and the effects of CR on them are also examined. CR was changed from 1.00 to 0.11. As a result, (a) the centerline maximum velocity u c/u m (u m: nozzle exit mean velocity) can be presented by u c/ u m=1.9 CR 3 -3.55CR 2+1.38 CR+1.53, and (b) the maximum of u c/u m=1.7 occurs at CR=0.27, and others were made clear.