Prediction of the Propeller-induced Hull Pressure Fluctuation via a Potential-based Method: Study of the Influence of Cavitation and Different Wake Alignment Schemes
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The propeller-induced hull pressure fluctuation is one of the main sources of the noise and vibration on ships. It has two main contributors which are equally important: the pressure induced by the displacement of mass, including the blade thickness and the cavitation bubble, and the pressure induced by the blade loading. The work in this paper is a continuation of previous work which introduced a sequence of numerical methods, which, in combination, can efficiently predict the propeller-induced hull pressures given the hull/rudder/propeller geometries, the ship speed, and the propeller RPM. A hybrid BEM/RANS method is first used to evaluate the effective wake on the propeller plane. Then, a BEM solver is used to calculate the propeller-induced hull pressures. The importance of the proper wake alignment model on the accuracy of the predicted pressure field in non-cavitating situations, was addressed before. In this paper, the method is extended to cavitating propellers. First, the wake alignment model is adjusted and improved for cavitating propeller conditions. Then, the unsteady wake alignment model is used to predict the propeller-induced hull pressures. The results are compared to experimental data, and the influence of different wake alignment models on the results is investigated.