Numerical analysis for the prediction of hull pressure fluctuation and underwater radiated noise induced by marine propeller cavitation

Abstract

In this study, viscous flow analysis by computational fluid dynamics (CFD) was performed on a five bladed conventional marine propeller in behind condition on the purpose of hull pressure fluctuation and underwater radiated noise (URN) prediction by propeller. The computation was conducted in model and full scale using the complete geometrical model of the propeller, hull and rudder for the direct comparison with the experiment and full scale measurement, respectively. The cavitation pattern and subsequent fluctuating pressure were investigated in model scale. A good agreement in cavitation pattern was found between the numerical analysis and experiment, yet the resolution of tip vortex cavitation needs to be improved. The tendency and amplitude of pressure fluctuation was reasonably predicted, especially for the 1st blade passing frequency (BPF). For the prediction of sound pressure level (SPL) in full scale, hybrid approach based on CFD and Ffowcs-Williams and Hawkings (FW-H) method is applied. In case of URN for full scale, SPL from the numerical computation was compared with the result from full scale measurement. SPL from numerical analysis is generally underestimated in comparison with the result of full scale measurement.