Measurement and Analysis of the Cavitation Noise of Propellers

This paper investigates the cavitation and non-cavitation noises produced by propellers based on a water tunnel experiment. The power spectrum of the noise is first analyzed through digital signal processing technologies，where the frequency features and regular patterns of the cavitation noise signal are obtained for forecasting purposes. Particularly，the accelerometers are employed during the experiment to measure the mechanical vibration signal，which reveals its severe interference on the underwater acoustic signal. Thus，a noise reduction procedure is applied to reduce the external noise. The results show that at high frequencies，the sound power level under the cavitating flow condition is 20 dB higher than that under the non-cavitating flow condition. Aside from these observations，the cavitation behavior of the propeller is examined with the help of high-speed cameras，while the measuring system and methods are also discussed in detail.