The Numerical Methods Research Of Coupled Vibration And Sound Radiation Of Underwater Structures

The vibration and sound radiation problem of a submarine is in fact a fluid-solid coupling problem. An excited underwater structure will vibrate and produce acoustic field in fluid, and the acoustic field reacts on the structure simultaneously. There is strong coupling between the structure's surface and water. Therefore, research on fluid-solid coupling is of engineering significance for evaluating the vibration and sound radiation performance of a submarine.Fluid-solid coupling problem is studied in both physics coordinate and mode coordinate with numerical methods in this paper.In physics coordinate, a new method based on finite element theory and boundary element theory is developed to compute the vibration and sound radiation of a underwater structure. Firstly, the structure's mass matrix and stiffness matrix is got by dealing with the structure with FEM software ANSYS. Secondly, the outer fluid field is treated with BEM,and the structure's additional mass matrix and additional damping matrix are computed by MATLAB program. Displacement response is then got by solving the dynamic equation taking account into additional matrices with program. Sound radiation is calculated by acoustic software SYSNOISE with the displacement response as boundary condition at last. The calculation tells that this method worth a further research.In mode coordinate, coupling modes of a cylindrical shell is calculated with numerical softwares in a new way and the modal additional mass is got. The relationship between the modal additional mass and vibration mode is studied too.Research in this paper is of some practical value and provides reference for a further research.