加纵肋无限长圆柱壳声散射

Acoustic scattering from an infinitely long cylindrical shell with lengthwise ribs

本文通过理论方法研究了水中加纵肋无限长圆柱壳的背向散射特性。壳体振动采用薄壳理论的Donnell方程描述,纵肋振动采用相互独立的梁的纵振动和弯曲振动方程描述。在圆柱壳周向使用模态展开和周期条件导出圆柱壳径向振速,并导出远场声压的解析解表达式。将圆柱壳周向模态看作其对应的离散周向波数,数值计算得到离散周向波数频率谱和背向声场形态函数谱。基于离散周向波数频率谱和背向散射声压形态函数频率谱分析了壳体中弹性波的激发、共振和再辐射条件。研究表明,加纵肋后,纵肋对圆柱壳的反力激发了亚音速的弯曲波,弯曲波在周向形成驻波共振并通过纵肋与圆柱壳的衔接点再辐射到远场。

The sound scattering from a fluid-loaded cylindrical shell with lengthwise ribs was studied by the⁃oretical approach in this paper.The shell motion was described by the Donnell equations,and the lengthwise rib was modeled as an elastic beam whose motion was decomposed into longitudinal and flexural vibrations.The analytical expressions of the shell vibrations and backscattering pressure in far-field were obtained via a circumferential mode expansion based on the periodicity in the circumferential direction.By regarding the circumferential mode as discrete circumferential wavenumber,the discrete circumferential wavenumber spec⁃tra and backscattering form function spectra were obtained numerically.After the shell ribbed,the subsonic flexural wave can be excited by the reaction forces of the ribs to the shell and can only radiate through the at⁃tachments of the ribs to the shell.