局部固体填充的水中复杂目标声散射计算与实验  

Acoustic scattering of a complex target with partially solid-filling immersed in water:numerical simulation and experiment

作　　者：张培珍[1,2] 李秀坤[1] 范军[3] 王斌[3] 

机构地区：[1]哈尔滨工程大学水声工程学院,水声技术重点实验室,哈尔滨150001 [2]广东海洋大学信息学院,海洋遥感与信息技术实验室,湛江524088 [3]上海交通大学,高新船舶与深海开发装各协同创新中心,海洋工程国家重点实验室,上海200240

出　　处：《物理学报》2016年第18期273-281,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51279033);黑龙江省自然科学基金(批准号:F201346);海洋工程国家重点实验室(上海交通大学)开放课题(批准号:1417)资助的课题~~

摘　　要：利用二维有限元方法研究水中局部填充的带球冠柱体目标声散射特性,所采用的数值方法可高效地实现精细化、宽带、复杂轴对称模型散射声场计算.根据数值结果解释壳体、填充物以及入射方位对目标散射远场的影响,确定复杂目标散射研究中所必须考虑的重要物理和几何构成.完成水中悬浮目标自由场声散射实验,收发合置条件下将目标旋转360?接收并测量不同传播路径回波到达时刻得到距离-角度伪彩色图像.以表面环绕波和"回廊波"产生理论为基础,解释内真空和局部填充模型正横入射时目标散射信号中几何回波和各种弹性波成分产生的机理.由于固体填充与弹性壳的耦合作用,频率-角度谱的正横方向两侧呈现外八字"碗"形共振曲线.通过对比,理论计算和实验得到的散射函数关键频谱峰值特性符合较好.Resonance peaks of spectral function transformed from echoes are the most important characteristics for distinguishing the different targets.So in frequency domain,response function is usually calculated with small interval in a wider frequency band to satisfy the demand of fast and high precision prediction in practical engineering.According to axis-symmetric model,we use 2 dimensional finite element method to solve the acoustic scattering problem efficiently,even when the scattering target has a large size and complex structure.This article focuses on the explanation of scattering characteristics of a special target,namely,a partially solid-filling cylinder with hemispherical cap and thin-shell.Supposing that the receiver and transmitter are in monostatic arrangement,we calculate scattering strength in far field in a frequency range of 50 Hz–10 k Hz,and give pseudo-color image represented by frequency-angle to describe influences of shell,filling and the orientation of the incident wave on scattering properties.According to the numerical results,the following conclusions are given： when the transmitter is facing the hemispherical cap（the cap has a vacuum inside,and the incident angle θ is equal to 0°）,the main contribution of scattered wave comes from the shell of target.Whenθ = 180°,the internal filling inhibits the elastic resonance of the shell,and plays an important role in the total scattering field.Because the acoustic impedance of the shell is much larger than that of the water,elastic resonance of the shell is more difficult to excite than that of the solid filling.While the material property of the solid filling is not significantly different from that of the water,so the elastic resonance of the filling fluctuates relatively fast,and the scattering function vibrates approximately with equal amplitude in a wider frequency band.When θ=90°,the sound wave is perpendicular to the axis of the cylinder,the shell and the filling work together on scattered waves.Once the incident angle deviates f

关 键 词：二维有限元 局部填充的带球冠柱壳 距离-角度时域回波 频率-角度谱 

分 类 号：TB56[交通运输工程—水声工程]