Predicting the dipole noises of the marine propeller with verifications by experimental measurements

Abstract

The objective of this paper is to predict the dipole noises caused by the marine propeller of an oceanography research ship, and compare the calculated results with the experimental data to verify the applied numerical method. As the propellers are of free-cavitation, such as those of submarines at diving depth and the surface vessels operating at cruising speed, the dominant noises are generated by the unsteady forces (i.e., dipole noise). Studies discussing the dipole noises generated by marine propellers are rare, and the measured results are always confidential for military purpose. In this paper, the unsteady forces were calculated by computational fluid dynamics (CFD), and transformed into the dipole strengths. The dipole strengths were then applied in the linear wave theory to solve the radiated noises. The scattered noises from the ship hull were computed by the iterating boundary element method. The experiments were carried out in the underwater anechoic chamber of the cavitation tunnel in National Taiwan Ocean University (NTOU). The results show that the comparisons between the numerical and experimental results are in good agreement.