刚性圆柱声散射特性的边界元法求解  

Acoustic scattering characteristics of rigid cylinder solved by boundary element method

作　　者：马建 汪海宾 高莎 刘晓宙[1] 刘杰惠[1] 何爱军[2] Ma Jian;Wang Haibin;Gao Sha;Liu Xiaozhou;Liu Jiehui;He Aijun(Key Laboratory of Modern Acoustics,Ministry of Education,and Institute of Acoustics,Nanjing University,Nanjing,210093,China;School of Electronic Science and Engineering,Nanjing University,Nanjing,210023,China)

机构地区：[1]近代声学教育部重点实验室南京大学声学所,南京210093 [2]南京大学电子科学与工程系,南京210023

出　　处：《南京大学学报（自然科学版）》2018年第5期875-886,共12页Journal of Nanjing University（Natural Science）

基　　金：国家重点研发项目(2016YFF0203000);国家自然科学基金(11774167);国家质检总局2017年科技计划项目(2017QK125);声场声信息国家重点实验室开放课题(SKLA201809)

摘　　要：声散射在检测声学和医疗成像诊断中是一个重要的现象,被检测物体外部形状的复杂性以及内部的缺陷或病变等会引起复杂的散射场.首先介绍了经典的无限长刚性圆柱在平面波入射下的声散射理论,引入了边界元法(the boundary element method,BEM),并且构建了模型计算边界元的声散射与理论解作对比.然后采用边界元法计算有限长刚性圆柱以及连线垂直于入射方向的两个刚性圆柱和不同轴长比的椭圆柱的声散射.计算结果表明,当无因次参量ka值比较小时,圆柱的尺寸比值以及双圆柱的情况对散射场分布的影响不大;当ka值比较大且圆柱的长度与半径比L/r值比较大时,无限长圆柱与有限长圆柱的散射场可以近似等效;增加双圆柱之间的距离,散射场的声压幅值和旁瓣的数目都会增加;椭圆柱的散射声场在轴长比a/b=2时声压较小.研究圆柱的散射问题具有丰富的意义,可以为目标物体的识别、缺陷的识别和定位等提供一定的理论依据.Acoustic scattering is an important phenomenon in the detection of acoustic and medical imaging diagnosis.The external complex shape and the internal defects or lesions of an object can lead to complex scattered fields,which may cause some difficulties in industrial and medical applications.This paper first gives the expression of scattered acoustic pressure by introducing the classical scattering theory for infinite rigid cylinder with the plane wave incidence,and the boundary element method（BEM）is utilized in acoustic scattering model and compared with the theoretical solution under different frequencies.Then the boundary element method is used to calculate the acoustic scattering of finite rigid cylinder,two rigid cylinders which is normal to the incident direction and ellipticcylinder under different rate of axis length.The calculation results show as follows.When the non-dimensional parameter kais relatively small,the size ratio of cylinder and the distance of two cylinders have little influence on the scattered field distribution.When the ratio of cylindric length and radius and the value of ka are relatively large,the scattered acoustic pressure in circumferential direction under different ka and in axial direction under the same ka shows the scattered field of infinite long cylinder can be approximately equivalent with that of finite long cylinder.By increasing the distance between the two cylinders,the amplitude of acoustic pressure of the scattered field and the number of side lobe will increase,which means the scattering effect becomes stronger.The scattered field of elliptic cylinder behaviors differentiation under different rates of axis length.The scattered acoustic pressure decreases first and then increases,and has a smaller value under the rate of axis length a/b=2.The study of the scattering problem for a cylindrical class is of rich significance,which can guide some scattered field analysis of similar workpieces and provide some theoretical basis for object recognition,identification and po

关 键 词：刚性圆柱 声散射 边界元法 散射场分布 

分 类 号：O426.2[理学—声学]