A Comparison of Acoustic and Visual Determination of Cavitation Inception on a Model Propeller

Although acoustic detection of cavitation inception has been shown to agree relatively well with visual detection, acoustic methods have generally not been used to detect cavitation inception during cavitation testing of model propellers. In addition, it has been suggested that noise measurements on model propellers be made at high frequencies to more properly represent the full scale noise. In this thesis, three different methods of acoustic detection were investigated. Two of these methods, the measurement of high frequency one-third octave band levels and the analysis of the complete noise spectrum between 10 and 50 kHz, met with some success, but were not equivalent to the capability of a visual detection method. The third method used, the demodulated analysis of high frequency cavitation noise, gave excellent agreement with visually determined results. (Author)