Experimental study of the structural and hydrodynamic noise characteristics of jet-induced supercavities

In this paper, submerged gaseous jet-induced ventilated supercavity experiments were concluded in a closed-loop water tunnel. The study shows the impact of ventilation rates, nozzle area ratios, and modulated ventilation on cavity morphology and flow noise characteristics. The flow noise generated by the ventilated supercavity does not increase proportionally with the ventilation rates. The ventilated supercavity with vortex tube gas leakage structures induced noise haystacks in the 70-90 Hz band in both the self-noise and radiated noise spectra. When the gas input is large enough to foam a partially broken cavity (PBC), further increases in the ventilation rate result in a rapid deterioration in the self-noise performance. The nozzle area ratio influences the gas exit velocity, and therefore the interaction between the jet and the cavity. As the area ratio increases, the ventilation rate required to convert a supercavity from intact cavity (IC) pattern to PBC pattern increases, which improves its self-noise characteristics. Finally, the study conducted modulated ventilation in both foamy cavity and IC patterns. The results indicate that proper modulated ventilation can transfer noise energy from the low-frequency noise peak to the modulated frequency, reduce the low-frequency amplitude of the radiated noise, and improve the flow noise.