An Experimental Study of Travelling-Bubble Cavitation Noise

Abstract

High-frequency travelling-bubble cavitation noise generated on a Schiebe headform is analyzed with reference to several existing noise theories which are based on the collapse of a single spherical bubble. After normalizing the noise level by a bubble event rate, the normalized cavitation number based on the minimum pressure coefficient provides a reasonable scaling factor, for the noise level radiated per collapse. At frequencies above 10 kHz and for free-stream velocities between 9.1 and 12.2 mps (30 and 40 fps), the trend of noise level per collapse versus normalized cavitation number correlated well with noise theories and was constant with flow velocity for constant normalized cavitation number. The energy density spectra were flat from 10 to 100 kHz regardless of the cavitation number or free-stream velocity for the range of these experiments.