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中文核心期刊

近底悬浮弹性球声散射机理分析

Analysis of acoustic scattering mechanism of a near-bottom suspended elastic sphere

  • 摘要: 基于二维周向分解方法进行了总场非轴对称背景下近底目标三维散射声场的数值快速计算, 研究了近底悬浮弹性球目标声散射机理。根据海底及目标耦合四路径模型的射线声学叠加原理, 给出了近底轴对称目标的二维有限元模型散射远场声压计算表达式。计算得到因界面引入的附加回波共同作用下的弹性球体目标散射频率−角度谱和频率−高度谱, 给出了耦合散射声场明暗交替干涉条纹的精确预报公式。通过数值计算及实验分析了目标在掠射角和悬浮高度变化时目标镜反射、弹性目标体内激发的弹性波与海底反射波相互耦合的传播规律及其对总场的影响, 讨论了因悬浮高度和掠射角变化产生的目标散射声场强度起伏机理。结果表明, 增大掠射角和悬浮高度均会使目标频谱相邻共振峰峰值间距减小, 并且利用海底与目标耦合作用声场的干涉条纹计算公式可以较好地对目标散射频谱信息进行预报。

     

    Abstract: Based on the two-dimensional circumferential decomposition method, this study focuses on the efficient numerical calculation of the three-dimensional scattering sound field for a near-bottom target in a non-axisymmetric background field. The method is applied to study the acoustic scattering mechanism of a near-bottom suspended elastic sphere target. The expressions for calculating far-field sound pressure in the two-dimensional finite element model of the near-bottom axisymmetric target are provided based on the ray acoustic superposition theory of the four-path coupling model between the seabed and the target. Taking into account the combined influence of the additional echo introduced by the interface, the frequency-angle spectrum and frequency-height spectrum of the elastic sphere target are computed, and an accurate predictive formula for the bright-dark alternating interference fringes of the coupled scattering sound field is presented. Through analysis of both numerical and experimental results, the propagation law of target mirror reflection, elastic waves excited in the elastic target body, and seabed reflection waves coupling with each other, as well as their influence on the total field, are explained when the glancing angle and suspension height of the target change. Moreover, the mechanism of intensity fluctuation in the target scattering sound field caused by changes in suspension height and glancing angle is discussed. The results indicate that increasing the grazing angle and suspension height will reduce the spacing between peaks of adjacent resonance peaks in the target spectrum, and that the interference fringe calculation formula for the sound field coupled between the seabed and the target can better predict the target scattering spectral information.

     

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