A Study on Pulsating Jet. 3rd. Report, Effects of Jet-Exit Conditions on Vortex Formations.

The purpose of this experiment is to make clear the effect of jet-exit conditions on the vortex formations of pulsating jets. Three exit conditions, two kinds of nozzles and an orifice are used in the experiment. One of these nozzles has a long parallel section, and the other has a short one. The pulsating jets are generated by Scotch yoke mechanism. The flow is visualized by a hydrogen bubble method. Obtained results are as follows: The flow patterns are strongly affected by jet-exit conditions. For the nozzle jets, the fre-quency of vortex formation agrees with that of the jet pulsation. For the orifice jet, a large scale vortex caused by the pulsation and a lot of vortices due to the shear layer in-stability are formed, and the vortices coalesce. The vortices of the orifice jet move down-stream faster than those of the nozzle jets.