有限波束作用下掩埋球体的散射声场计算

Scattering of buried sphere insonified by a finite-beam source

计算并分析了海底掩埋物体的三维散射声场。采用"等效垂直线列阵"方法来进行有限波束的建模,并将浅海波导中点声源散射声场的波数积分计算方法,推广到有限波束作用下海底掩埋物体的散射场计算,本文导出了物体位于沉积层中的散射声场计算公式。计算结果表明,在波导中垂直面内的散射声场,与沉积层中点源形成的声场非常相似;当距离较远时,散射声波呈柱面波衰减。文章还分析利用海面反射以提高散射能量的可能性,表明波束指向性及波束宽度对散射声场有较大影响。

Calculation and analyses of the 3-D scattering field from a buried soft sphere is addressed. The concept of ＂equivalent vertical line array directivity pattern＂ is adopted to generate a finite beam. Based on the spectral approach for scattering in the waveguide, the paper derives a formulation for scattering of buried target insonified by a finite-beam source. Numerical example shows that, the scattering field of the waveguide in a vertical plane is similar to the field radiated from a point source in the sediment, and that the scattered wave behaves like a cylindrical wave at large ranges. The possibility to improve scattering strength by reflects the beam by the sea surface is discussed; it is shown that the beam directivity and beam width have great impact on the scattering field.