Acoustic Detection of Cavitation Inception

Abstract

Cavitation phenomenon can cause deterioration of the hydraulic performance, damage by pitting, material erosion, structure vibration and noise in fluid machinery, turbo-machinery, ship propellers and in many other applications. Therefore, it is important to detect inception of cavitation phenomenon. An experimental study has been carried out in order to investigate the noise radiated by various cavitating sources to determine the validity of noise measurements for detecting the onset of cavitation. Measurements have been made measuring the noise radiated by a number of configurations in a water tunnel at various operating condition to determine the onset of cavitation. The measurements have been conducted over a frequency range of 31.5 Hz to 31.5 kHz in one-third octave bands. The onset of cavitation was measured visually through a Perspex side of the working section of the water tunnel. Moreover, a theoretical estimate of the pressure radiated from the cavitation nuclei at their critical radii and their frequency was presented. Tests indicated that, generally, at the point of visual inception there was a marked rise of the sound pressure level in the high-frequency noise, whilst the low-frequency noise increased as the cavitation developed. This finding was supported by the theoretical estimate of the pulsating frequency of cavitation nuclei. The results illustrated that the visual observations of inception confirm the noise measurements.

Acoustic Analysis of Vortex-based Cavitation Devices: Inception and extent of cavitation

“…They only consider the overall sound pressure level obtained through frequency spectra and no detailed analysis of nature of spectra is reported. Hosien and Selim 35 carried out acoustic measurements in the range 31.5 Hz to 31.5 kHz using a one-third octave band analyzer. After analyzing the sound pressure at various frequency bands, they observed that there was a clear and marked increase in pressure level at 4 kHz at the time of inception.…”