有限长双层壳体声辐射理论及数值分析

Theoretical and Numerical Analysis on Sound Radiation of a Finite Double Shell

研究流场中有限长加筋双层圆柱壳受径向点激励的振动和声辐射性能。壳体的振动用 Flügge壳体方程描述 ,将加强构件等价为对内外壳体的支持力 ,采用 Helmholtz波动方程、壳体表面的边界条件和傅氏变换方法求解声压的表达式 ,然后将其引入壳体振动方程 ,最后求解双层壳体声 -流体 -结构耦合方程 ,计算结果用辐射声功率、表面振动均方速度级和辐射效率的形式表示。讨论了有限长单、双层壳体声辐射性能的差别以及双层壳体壳间连接形式和实肋板参数的变化对其声辐射性能的影响 ,得出结论 :当内壳受激振动 ,通过外壳向外场辐射噪声时 ,其主要通道为连接内外壳壳体的实肋板 。

The vibration and sound radiation from a finite stiffened double cylindrical shell driven by a point force on the shell surface in the radial direction are studied in this paper. The Flügge equation of thin shell is applied to describe shell motion. The effects of stiffeners are treated as reverse forces and moments on the cylindrical double shell. The expression of sound pressure is obtained by solving Helmholtz equation with the continuity conditions of the displacement on the interface of fluid structure and using Fourier transform, which induces the equation into the vibration equation. The vibration equation coupled by the sound fluid structure is sloved in the end. Theoretical results of radiated power, radial quadratic velocity and radiation efficiency are presented. The differences between the characteristics of sound radiation of the finite single shell and the double shell, the effects of the types of the connection between the inner shell and the outer shell, and the effects of the parameters of annular plates on the sound radiation are discussed based on numerical analysis. It is concluded that when the inner shell driven by a point force and the sound radiates to fluid through the outer shell, the main path is the annular plate connecting the inner shell and the outer shell, and the fluid medium in the shell is the next way.