Numerical assessment of underwater noise radiated by a cruise ship

The present paper deals with a methodology for the prediction of propeller-induced acoustic pressures and associated ship response, having considered propellers as the main acoustic source onboard ships. Semi-empirical and numerical approaches have been coupled for the characterisation of the propeller and the determination of the radiated acoustic field, respectively. The boundary element method has been used for numerical analyses, and a commercial solver has been adopted. The procedure has been applied to a cruise ship, and numerical results have been compared to the available experimental measurements. Other two different ships have been taken into account in order to test the methodology. Results show that the influence of the structural finite element mesh of the ship on the computation is comparable to acoustic characterisation of the propeller. Furthermore, it is found that the reliability of semi-empirical methods is not completely satisfactory; nevertheless, they are currently used at an early design stage as common practice.