Flow Sensitivity Analysis for the Feedback Loop Phenomenon of Subsonic Jet Noise Generation

In this study, the feedback loop phenomena caused by upstream propagating waves (guided jet waves) in a Mach 0.9 free jet are investigated. A point source is placed at the end of the potential core of a three-dimensional free jet as a noise source in the jet and the sensitivity of the flow field is measured. The results show that the case \(St_D=0.47\) has the highest sensitivity, which was consistent with the allowable frequency range of the guided jet wave. This result supports the idea that guided jet waves cause free shear layer instability waves.