水下环形凹槽圆柱体散射声场空间指向性调控  

Manipulating spatial directivity of acoustic scattering from a submerged cylinder by means of annular grooves

作　　者：周彦玲 范军[1] 王斌[1] 李兵[1] Zhou Yan-Ling;Fan Jun;Wang Bin;Li Bing(State Key Laboratory of Ocean Engineering,Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学,海洋工程国家重点实验室,高新船舶与深海开发装备协同创新中心,上海200240

出　　处：《物理学报》2021年第17期125-132,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11774229)资助的课题.

摘　　要：本文提出一种具有深度梯度的环形凹槽结构,可用于调控水中有限长刚性圆柱体散射声场空间指向性.基于声学相位阵列理论分析了环形凹槽圆柱声散射空间指向性改变的机理,研究表明:凹槽深度方向相位延迟和凹槽间Bragg散射的相互作用使得平面声波垂直于圆柱方向入射其正横方向散射声波发生偏转.采用有限元方法讨论了凹槽结构参数如占空比、梯度等对圆柱散射声场空间分布特征的影响规律.多个不同深度梯度环形凹槽单元组合圆柱体散射声场数值计算和实验结果显示:具有环形凹槽结构圆柱体正横方向散射声波均匀偏转到预定的空间范围内,使得圆柱体声散射场空间指向性均衡化,改变了圆柱整体的散射特征,这为水下目标声隐身设计和声波定向传播提供了新的方法.An annular groove(AG)structure with depth gradient is proposed which can manipulate the spatial distribution of the acoustic scattering field for a finite rigid cylinder in water.An analytical analysis is given for better understanding the underlying mechanism of the abnormal scattered wave,which can be accomplished by using the phased array theory.When the plane acoustic wave is normally incident,the scattering acoustic wave in the transverse direction of the cylinder deflects,which is due to the interaction between the phase delay modulated by the AG structure with varying groove depths and the Bragg scattering of adjacent grooves.The finite element method is used to calculate the acoustic scattering field of a finite rigid cylinder with annular grooves and obtain the frequency and spatial distribution characteristics.How the structural parameters such as depth,gradient,and duty ratio of the annular grooves affect the acoustic scattering field is discussed in detail.The results show that the target strength in the transverse direction decreases linearly with duty ratio increasing while the target strength in the deflection direction of the acoustic wave increases with the duty ratio until δ=30%,after which it remains almost constant.When the incident acoustic wave is fixed,the acoustic scattering wave of the AG cylinder can be deflected by designing the gradient appropriately,and the deflection direction is independent of the frequency.Numerical and experimental results for a cylinder with multiple annular-groove units show that the spatial directivity of the scattering field of the grooved cylinder changes,and the target strength is enhanced at six pre-designed deflection angles.Meanwhile,the deflected acoustic wave has a certain width and the interference among periodic structures of the AG units exists,which makes the spatial directivity of the scattering field of the cylinder equalize and changes the scattering characteristics of the cylinder,thereby providing a theoretical basis for designing three-dimens

关 键 词：环形凹槽结构 声波偏转 圆柱体 声散射 

分 类 号：O42[理学—声学]