Dynamics of round jet impingement

International audienceThe impingement of a round jet issued from a convergent nozzle is known to produce intense tonal noise. These tones are generated by a feedback process involving a Kelvin-Helmholtz instability wave and an upstream propagating wave. The frequency structure of these tones is experimentally explored by varying the jet Mach number from 0.7 to 1.5 and we observe evidence that neutral-upstream modes of the jet are active in the feedback process. Tone frequency predictions obtained using the intrinsic jet modes are compared to the standard model involving free-stream acoustic waves: the neutral waves model provides a convincing agreement with the experimental data