Numerical simulation for effects of submarine fairwater shape on flow-induced noise

A three-dimensional computation code is developed to predict the flow-induced noise during a submarine navigation. In this code, steady RANS flow field is firstly computed by using the SIMPLE method with multi-block grid, and then unsteady flow-field is solved with iterative time-marching method and the DES turbulence model. On the basis of the flow simulation results, the time history of sound pressure is obtained with the Lighthill acoustic analogy. Numerical simulations for a scale-up submarine model of SUBOFF and three modified models are performed by this procedure. The noise spectra at observation points are calculated for different submarine fairwater shapes. Moreover, the distributions of the fluctuating pressure level on the surface of typical submarine models are obtained. The computation results show that the swaying motion in the wake flow can be controlled when the rear edge shape of the fairwater is remodeled from rectangle into trapezia, and the submarine flow noise can be effectively reduced by 5 dB for the optimal submarine shape.