水面舰船流噪声数值预报研究与应用

在梳理流噪声数值预报方法的基础上,采用流场大涡模拟（large eddy simulation,LES）和声学边界元（boundary element method,BEM）方法在频域内计算预报了船体流噪声谱曲线,求取了其等效声中心.LES计算时选用动力学Smagorinsky-Lilly（dynamic Smagorinsky-Lilly,DSM）亚格子应力模型,流噪声由船体壁面脉动压力和法向速度特性决定,声源节点和声节点变量传递采用一对一的守恒传递方式.结果表明：某型船在航速14 kn时,裸船体流噪声在20 Hz~2 kHz频段内总声源级为133dB;当计算有效频段扩展到20 kHz时,总声源级达143.3 dB.流噪声主要来源于兴波引起的涡量,且主要集中于100 Hz~10 kHz频段.球首尾流区和船体尾涡区对流噪声辐射量贡献明显,特别是球首尾流区,对全频段都有明显的贡献,为水面舰艇流噪声研究提供了一条新的途径.

Study on numerical prediction of surface ship flow noise

On the basis of summarizing the methods of numerical flow noise prediction,a ship’ flow noise spectrum and its equivalent acoustic source are determined numerically by combining the large eddy simulation（ LES） and boundary element numerical acoustics in the frequency domain. Dynamic Smagorinsky-Lilly Model（ DSM） is applied to subgrid-scale stress tensor in the process of LES simulation. The fluctuation pressure and normal velocity distribution on the hull surface are treated as flow noise source with conservative transformation to the acoustic nodes. It is shown that the total sound source level of flow noise reaches 133dB in 20Hz~2kHz frequency band and 143. 3dB within 20kHz broadband at the speed of 14 knots. The main source of flow noise comes from vorticity induced by the ship wave. And it concentrates mainly in 100Hz~10kHz band. Exactly,the vorticity of sonar shell and hull plays an important role in radiated noise. More attention is needed to pay to it in design. A new practical method is presented to measure the surface ship flow noise in the field of naval architecture.