水中板声辐射的声功率模态分析

由于水中结构的振动声辐射要考虑流体加载效应,因此水中结构声辐射的模态分析也与空气中的有所不同。基于辐射声功率的二次型表达式,采用有限元和Rayleigh积分耦合方法,对板结构的水下声功率模态进行了计算分析研究,通过辐射效率、模态振型和辐射声功率等探讨了其特点。结果表明以激励力为变量、考虑了结构阻抗的水下声功率模态具有各阶模态声辐射独立、低频时前几阶模态(特别是第1阶模态)的声辐射占主导地位、模态辐射效率峰值和模态振型物理意义清楚等特点,在水下结构振动声辐射的分析和控制方面有一定实用价值。

Acoustic power-mode analysis of sound radiation from underwater plate

Because of fluid loading, the modal analysis of sound radiation of underwater structure is different from that in air. The modal analysis of sound radiation from an underwater plate is carried out by using coupled finite element /Rayleigh integral method. The expressions of acoustic power modes are obtained based on the quadratic form of acoustic power. The characteristics of the acoustic power modes are compared in their radiation efficiencies, mode shapes and radiated power contributions. The numerical results show that the acoustic power modes expressed by the excitation force have the advantages in taking account of the structural impedance, no modal coupling of sound radiation between modes, the first few modes（especially the first mode） dominating the total sound radiation, direct physical explanations of the mode shapes and the peak values of the mode-radiation efficiency. So, the acoustic power-mode analysis is more favorable in analysis and control of sound radiation from underwater structure.