内部声激励下水下加筋圆柱壳声辐射特性研究

摘要

A method for calculating the outside sound radiation of an enclosure cylindrical cabin hous-ing machines which produce both internal noise and mechanical forces is proposed. According to Flügge theory and the Helmholtz equation, a ‘stiffened cylindrical shell-cavity-outside radiated sound field’ coupling equation is presented. To solve this coupling equation, the displacements of the cylin-der are expanded in a series of its eigenmodes. The displacements of the cavity are expressed by a-coustic modes. And the inside and outside sound pressures are treated as reaction forces on the shell. Then according to the orthonormal relations of modes of the shell, the solution method of the coupling vibration equations expressed by shell’s displacements is given. The sound radiation characteristics of a submerged stiffened cylindrical shell inspirited by harmonious exciting forces are reappeared. The results agree well with the relative reference papers, thus demonstrating the rationality of the theoretical method. Then the effects of the cut-off mode order numbers of the cavity on the calcula-tion accuracy are described. Finally, the influences of different positions of an interior source on a-coustic of the shell are obtained, and the comparisons of sound radiation properties of interior sources which have the same phases and different phases are carried out. The theoretical solution and the discussion are favorable for noise reduction of submerged stiffened cylindrical shells.%文章从Flügge薄壳理论和Helmholtz波动方程出发推导了有限长加筋圆柱壳受机械激励力和内部空气噪声激励时的耦合振动控制方程。为求解该封闭声腔-有限长加筋圆柱壳-外部辐射声场的耦合方程，将壳体位移形式沿周向和轴向用模态叠加的双级数展开，同时将圆柱型封闭声腔沿周向、轴向以及径向用三向级数展开，得到基于壳体位移的流固耦合振动方程。进一步根据模态正交性求解方程并与相关文献对比验证了理论方程的正确性。最后基于文中的理论推导，讨论了内部声腔截止模态阶数对求解精度的影响，进一步分析了内部声源不同位置、内部多个声源情况下的外场声辐射情况。分析结果对圆柱壳体结构的声学设计具有一定的参考价值。