双层周期加肋有限长圆柱壳声散射精细特征研究

Acoustic scattering from the finite periodically ribbed two concentric cylindrical shells

研究了双层周期性加肋有限长圆柱壳在水中的声散射特性.壳体振动用薄壳理论的Donnell方程描述,环肋振动用相互独立的薄板纯弯曲振动和平面应力状态下的振动方程描述,忽略弦间流体对环肋轴向力的作用.数值计算给出远场收发合置情况下的周向目标强度和角度-频率谱图,并据此进行机理分析.计算结果表明远场散射声场中除壳体弹性贡献外,弦间流体以及环肋与内外壳的相互作用对散射声场的贡献也是很重要的,并且在角度-频率谱中出现了舷间流体引起的流体附加波以及周期环肋引起的Bragg散射等回波精细特征,其中流体附加波是双层加肋圆柱壳声散射最重要的散射精细特征,是以往单层圆柱壳声散射所不具有的现象.最后通过实验对理论推导进行了验证,实验与理论基本符合.

Acoustic scattering from the submerged finite periodically ribbed two concentric cylindrical shells, insonified by an incident plane wave, is studied. Motion of the shell is described by Donnell equations, while the motion of the disks is described by thin plate motion equations and plane stress equations ignoring the effects of axial forces on the disks.Through angle-frequency spectra, besides the elastic waves of the shells, the contributions of the fluid between the inner and outer shells and the interaction of the inner and outer shells with the disks play an important role in the far scattering field. There are fine echo waves such as Bragg scattering and fluid-added waves excited on the angle-frequency spectra.Finally the theories are verified by experiments.