利用声辐射模态重构任意目标的散射声场

水下目标散射声场的重构可以作为水下目标散射特性的研究基础。本文主要利用声辐射模态对水下目标进行散射声场重构研究。首先,在借助声传递矩阵给出的任意结构声辐射模态的流体域求解方法基础上,通过理论证明了目标的散射声压与声辐射模态具有函数关系。其次,借助声场分布模态的概念,同时考虑到声场分布模态病态及声压测量易受噪声污染,提出基于声辐射模态的正则化散射声场重构算法。仿真结果表明,波数越低,重构所需声辐射模态阶数越少,在较高波数时仅需总模态数的大约20%即可对声场进行重构。与基于边界元的声场重构算法相比,计算量减小了至少80%,且克服了赫姆霍兹积分方程最小二乘法仅对球壳结构的重构效果较好而不适用于长条形结构重构的缺陷。

Acoustic scattering field reconstruction for arbitrary targets using acoustic radiation modes

The acoustic scattering field reconstruction of underwater targets can be taken as the basis of the underwater targets scattering characteristic research. Applying acoustic radiation modes (ARM) to the acoustic scattering reconstruction of underwater targets is the main focus of the paper. Firstly, based on the ARM solving method of arbitrary structures in fluid domain, which is with the aid of acoustic transfer matrix (ATM), it was theoretically demonstrated that there was functional relationship between scattering pressure of targets and ARM. Secondly, by means of the concept of the acoustic field distribution modes and due to the ill-conditioned property of acoustic field distribution modes and the noisy contamination of acoustic pressure measurements, the regularization reconstruction algorithm of acoustic scattering field based on ARM was proposed. Simulation results show that the order number of ARM needed for reconstruction is smaller for the lower wavenumber and that only about 20% of the total modes number can complete the reconstruction for the higher wavenumber. Hence, compared with the BEM based reconstruction algorithm, the computational amount of the ARM based one is reduced to at least four-fifths. And the drawback of Helmholtz equation-least squares (HELS) which has a better construction results for spherical structures but not for strip shaped structures has been overcome.