An Expression of Inception Cavitation Number

The inception cavitation number a 1 and corresponding propeller revolutions RPM are essential parameters for the prediction of the propeller noise. While RPM and a depend on many factors, the thrust loading coefficient Te and pitch ratio P/0 are important. In this contribution a simple expression, which comes from classical Burrill ship trial cavitation chart and modern model noise experimental analysis is presented. Based on the expression the predicted results for the noise spectra (SPL, vs. 1/3 octave frequency) are acceptable.