Research On Numerical Predicting Method For Broadband Noise Of Marine Propeller Based On LES

The noise of propeller is one of the three most important sources of marine noise. It will not only disturb the crew and passenger on board, influencing the eco-environment, but also have direct impact on the acoustical performance of warship. Predicting method of noise is an important technological way to develop the acoustical performance of propeller. The numerical predicting method for the broadband noise is studied using the large eddy simulation method coupling with acoustical boundary element method in this paper.In order to establish numerical predicting method, firstly, the computational domain size and grid generation strategy are studied. The numerical method is verified by comparing with the experimental result. The numerical simulation of unsteady flow is accomplished by LES with dynamic Smagorinsky subgrid model and the pressure fluctuation on blade surface is studied.Secondly, based on pressure fluctuation obtained in the unsteady flow, the broadband noise of propeller is calculated with acoustical BEM. The influence of grid quantity, computing steps, time steps is studied. The sound pressure fluctuation characteristic, the sound radiation in circumferential and axial direction, the sound pressure contour and directivity are discussed and match well with the rule of sound radiation. The numerical predicting method for broadband noise is established.Lastly, the broadband noise in different conditions is calculated, and the spatial variation characteristic is studied. Numerical results are in good agreement with the experimental results in 1.25 k Hz~4k Hz frequency, verified the reliability of the predicting method.Through the study in the above, the 3D whole propeller numerical method for broadband noise is established in this paper, providing a reliable way in developing silent propeller.