水下三弹性柱壳耦合声散射特性研究

为研究3个并排无限长弹性圆柱壳受垂直于柱轴方向的平面声波作用的声散射特性,采用Fourier级数展开法建立了圆柱壳声散射数学物理模型,考虑了三圆柱壳弹性振动声辐射和刚性声散射,建立了3个壳体辐射声场和刚性散射声场的耦合作用关系,比对了等效散射强度的刚性散射分量与弹性散射分量,并分析了三壳体等效散射强度特性。计算结果表明:当ka₂>40,在频率f=3000 Hz以上频段,弹性分量对等效散射强度变化趋势的贡献可以忽略。当ka₂>30,在频率f=2400 Hz以上频段,弹性散射分量对等效散射强度影响不超过3 dB;三壳与单壳的等效散射强度在0°入射角方位相当,其它方位三壳体等效散射强度明显大于单壳体。本文的理论公式可推广到任意数量阻抗柱的声透射和声反射问题。 

Sound scattering characteristics of three underwater paralleling flexible cylindrical shells

To investigate the sound scattering characteristics of three paralleling flexible cylindrical shells with plane incident wave,a mathematical model is established with Fourier series expansion method which involves the flexible vibration,sound radiation and rigid scattering of each shell and their coupling through the sound field.With the model,the difference between the flexible radiation term and rigid scattering term of the sound field of three combined cylindrical shells is calculated and analyzed,ais well as the scattering strength of the shells.The results demonstrate that the flexible radiation term is supposed to be ignored for ka₂>40(f>3000 Hz),and for the instance of ka₂>30(f>2400 Hz),the scattering strength error without the flexible radiation term is less than 3 dB.The scattering strength of three shells is approximately equal to the scattering strength of single shell while the incident angle is 0°or vicinity angle,whereas the scattering strength of multi-shells is higher than that of single shell for the distinct incident angle.The mathematical model in this paper could be easily extended to solve the problems of scattering and reflection of random number of resistant cylindrical shells.