不同介质中声辐射相似性

研究不同介质中声学相似条件,可为空气噪声实验数据推算相应条件水下辐射噪声,替代复杂水下实验提供依据。因此,首先运用了因次分析法对任意不同介质中的声辐射相似性进行了分析;然后,采用结构有限元耦合流体边界元理论,利用NASTRAN计算模型表面流固耦合振动;最后,通过FORTRAN边界元程序计算辐射声场;以加肋圆柱壳为对象在水和空气两种典型介质中进行了数值模拟验证。理论推导与数值计算的结果一致性表明:不同介质中两个几何相似、表面振动相似的系统间结构表面振幅与该系统几何尺度成正比、表面振动波波长与该系统传声介质中声波波长成正比时,两个模型的无量纲声压相等。

Study of similarity of sound radiation in different fluids

Based on the study of the similarity of sound and vibration in different fluids,the sound experiment data gained in air can be used to calculate underwater noise.Firstly,the dimensional analysis method is used to analyze the similarity of sound radiation in arbitrary fluid.Secondly,the FEM/BEM method and NASTRAN are adopted to calculate surface vibration.Finally,FORTRAN BEM program is applied to calculating the sound radiation and the sound pressure of ring stiffened cylinder in water and air,two typical fluids.The theoretical analysis and numerical calculation show that when the ratio of surface vibration equals the geometry scale ratio and the ratio of surface vibration wavelength equals the sound velocity ratio,the non-dimensional sound pressures of two systems are equivalent.