Numerical study of flow-excited noise of a submarine with full appendages considering fluid structure interaction using the boundary element method

Large eddy simulation (LES) is applied to simulate the flow field around a submarine with full appendages. The predicted ship resistance, velocity distributions and surface pressures are validated by experimental data. Dynamic velocity responses of the structure are obtained by solving the fluid-solid coupling equations. The flow noise and flow-excited noise of the submarine are predicted using the boundary element method (BEM). Flow noise predicted by the BEM and the Ffowcs Williams-Hawkings (FW-H) equations are compared and discussed. The spectra of flow-excited noise are different from those of flow noise, and the sound pressure level of flow excited noise is larger than that of flow noise, especially when structural resonance occurs. Flow-excited noise rapidly decreases in the near-field and maintains a slow attenuation rate in the far-field. The influence of ship speed on flow-excited noise is investigated, and results show that the spectral characteristics of flow-excited noise of the submarine change greatly with different sailing speeds. To achieve noise reduction, different shell thicknesses and different numbers of longitudinal girders are investigated. It is found that increasing the shell thickness and the number of longitudinal girders can indeed reduce noise emission. It should be noted that the noise reduction effect might differ.