Aeroacoustic Properties of Supersonic Cavity Flows and Their Control

Abstract

A detailed experimental study of supersonic, Mach 2, flow over a 3D cavity was conducted using shadowgraph, particle image velocimetry (PIV), and unsteady surface pressure measurements. Large-scale structures in the cavity shear layer and visible disturbances inside the cavity were observed. The PIV data reveals the highly unsteady nature of the entire flowfield and the presence of a large recirculation zone with reverse velocities as high as 40 % of the freestream velocity. Supersonic microjets at the leading edge are used to control the cavity flow and suppress resonance in the cavity. Using minimal mass flux through the microjets, overall sound pressure level (OASPL) was reduced by greater than 9 dB with tonal reductions greater than 20 dB. The PIV data reveals that microjet injection modifies the cavity shear layer and results in a significant reduction in the unsteadiness of the cavity velocity-field.