Analysis of the unsteady thrust pulsation and noise line spectrum of ship propellers

Unsteady thrust pulsation and induced noise of ship propeller under non-cavitating conditions is investigated. The main purpose is to check the validity of theoretical prediction method of unsteady thrust pulsation of propeller. The thrust pulsation in non-uniform flow conditions of propeller is calculated with potential-based panel method, and corresponding quantity is obtained by measurement using unsteady propeller dynamometer after the complete hull model in large cavitation tunnel. And then the time-dependent thrust data are used as sound source to predict the far-field noise line spectrum. The maximal discrepancy of the calculated unsteady thrust coemcient of the first blade passage frequency (BPF) with the test results is 29.3%, and the variance of the first BPF noise line spectrum is 3.0 dB. The investigation reveals that the prediction precision of propeller's thrust pulsation with panel method have reached higher accuracy, and the researches provide the physical base and significant parameters for prediction of ship propellers' low frequency noise line spectrum.