Unsteady cavitation characteristics and alleviation of pressure fluctuations around marine propellers with different skew angles

Cavitating flow around two marine propellers with different skew angles, a conventional propeller (CP) and a highly skewed propeller (HSP), operating in the non-uniform wake was simulated using a mass transfer cavitation model and the k-omega SST turbulence model. The numerical model reasonably predicted experimental data for the unsteady cavitation patterns as well as the oscillation amplitudes of the dominant pressure components. The results indicate that the effect of skew angle is very important on the cavitation characteristics as well as the pressure fluctuations and that the amplitudes of pressure fluctuations for the HSP are 50∼70% less than that for the CP. Therefore, the skewed propeller will reduce noise and vibration compared to the conventional propeller. Furthermore, the numerical model verified the relation between the hull pressures and changing cavitation patterns as the blades sweep through the high wake region. The results demonstrate that volumetric acceleration of entire cavity around a propeller blade is the main reason for the pressure fluctuations, which agrees with previous experiments.