全附体潜艇流噪声数值计算

运用计算流体力学(CFD)和边界元(BEM)相结合的方法,预报全附体潜艇流噪声,得到特征点的总声级和潜艇声场指向性分布规律。首先建立具有全部附体潜艇的几何模型并对流场计算域进行全结构化网格空间离散,然后采用雷诺时均方法(RANS)计算潜艇定常流体特性,得到的艇体阻力和压力系数与文献提供试验值吻合良好。再以流场定常计算结果为初值,计算潜艇非定常流动特性,得到声偶极源项,作为边界元求解辐射声场的输入量。声场计算通过在频域中求解福茨.威廉姆-霍金斯方程(FW-H)方程来完成。计算得到了潜艇表面的辐射声源强度分布,验证了流动转捩区是主要的发声部位,并分析了不同频率下声指向性的变化规律。计算所得结果与一般声学规律较为吻合。

Numerical Calculation of Flow Noise of Submarine with Full Appendages

A method combined the computational fluid dynamics (CFD) with the boundary element method (BEM) was used to predict the flow noise of submarine with full appendages. The total sound pressure level at typical measured point and acoustic directivity of the submarine were obtained. Firstly, a geometric model was established for the submarine with full appendages and the flow field's computational region discretization was carried out by using structural grid. Then, the steady flow performance of the submarine was calculated by adopting Reynolds time-averaged method(RANS). The obtained resistance and pressure coefficient along the hull coincides better with the experiment data in references. After that, taken the calculation results for the steady flow as initial values, the unsteady flow performance of the submarine was calculated to obtain the sound dipole sources which were used as the input parameters of the boundary element calculation. Finally, the acoustic far-field was calculated by solving Ffowcs Williams-Hawkings(FW-H) equation in frequency domain. Through these calculations, the surface sound sources of the submarine and the sound directivities of the 3D sound field were analyzed. The results show that the greatest noise area comes from the transition region in flow.