On Control Factors for the Oscillation of a Simplified Flip-Flop Jet Nozzle

Abstract

The authors experimentally investigate a self-excited oscillatory phenomenon of a two-dimensional confined jet with a cylinder as a downstream target, especially for the effect of a streamwise target size a. As a result, the authors find that the jet’s dominant frequency fD can be approximately predicted by the proposed empirical formula (Hirata et al., 2011), whenever the jet stably oscillates at various values of the non-dimensional streamwise target size a/b where b denotes the length scale of the jet’s breadth. The effect of a/b upon the occurrence of the stable jet oscillation is negligible for a/b ≤ 10. Then, the occurrence of oscillations can be predicted by the proposed empirical formula (Hirata et al., 2009). On the other hand, for a/b > 10, the a/b effect is not negligible. In addition, the authors conduct numerical analyses, which reveal the two-dimensionality of the concerning phenomenon.