Flow-excited submarine structure acoustic prediction based on a refined integral algorithm

Based on the coupling CFD/BEM/FEM model of the Suboff submarine,the flow-excited submarine low-frequency vibration and underwater radiated noise were studied.Firstly,the transient flow of the submarine 3D fluid field was calculated via CFD tool,and the fluctuated exciting forces on submarine hull were abstracted and loaded onto the FE model via data projection for harmonic analysis.Then the flow-excited noise was calculated via a refined integration algorithm of sound field with the hull responses boundary condition.In this algorithm,the singular and near-field integral coefficients in HBIE were calculated via a self-adaptive quadrature scheme until converged at the error of 10-4 when the refined level up to 6.Results show that,both the sound power and sound radiation efficiency appear distinct peak value,and the line spectrum of the flow excitation induces hull compulsive vibration and enlarge underwater noise,while band spectrum induces structure resonance and stronger underwater noise.So,to reduce the flow-excited hull radiated noise,both the shape of the hull and its interior structures should be optimally designed to improve the wake of the hull and reduce the turbulent intensity,and the key point is to avoid resonance.