Cavitation phenomena, propeller excited hull pressure amplitudes and cavitation scale effect

The cavitation research, described here and carried out with the laser-scattered-light-technique, demonstrates the large influence of the free air content on cavitation phenomena and propeller excited pressure fluctuations in a cavitation tunnel. Another result of this research, based on full scale investigations, is that in the free sea a large number of nuclei is always present. Therefore for equal propeller loadings substantial differences of the cavitation extent can apparently never occur in different sea regions.The experimental research was supported by theory, applied to hemispherical nosed bodies and model propellers.The comparisons between model and full scale cavitation phenomena which cause hull pressure fluctuations show remarkable differences. The reason is the scale effect of the cavitation due to different absolute pressures on the propellers in model and full scale.Other published model/full-scale comparisons considering this scale effect are discussed.