双层加肋球壳回波现象分析

Analyses on the echo phenomenon of ribbed double spherical shells

双层加肋壳体是水下目标的典型结构。实验观测到双层加肋球壳回波的频率-角度谱在角度域呈现强烈的周期性振荡,在2 kHz～10 kHz频率范围内,这种振荡从低频到高频越来越明显。为了解释所观测到的现象,利用修正的板块元算法(Modified PEM)计算了不同入射角、不同频率下双层加肋球壳的回波,并与实验结果进行了对比分析。结果表明,目标强度随入射角的周期性剧烈起伏主要是由壳间肋板声散射导致的。

Ring-stiffened double shells are typical structures of underwater targets. In underwater target experiments, periodic sharp fluctuation on the frequency-angle spectrum of echo from ring-stiffened double spherical shells （RSDSS） is observed when the incident angle changes linearly, and this phenomenon becomes apparent when the incident sound frequency changes from 2kHz to 10kHz. In order to explain the phenomena, the target strength of RSDSS at different incident angles and frequencies is calculated using a modified Planar Elements Method （PEM）. The theoretical and experimental results are compared. It is found that the periodic sharp fluctuation of echo from RSDSS is mainly attributed to acoustic scattering from rings between the two shells.