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建立一种基于虚源法和物理声学方法计算浅海波导中目标回声的射线声学方法。入射声线经过两个界面的多次反射有无限多条,每条入射声线由目标反射后又会产生无限多条到达接收点的声线。将各种组合的散射声场求和得到总的回波声场。用射线声学方法计算了Pekeris波导中半径10 m的绝对软球的回声随距离的变化。与已有文献中波动声学方法的计算结果对比,两者在平均值和下降趋势上符合。计算表明,波导中球和一些圆形目标的等效目标强度(ETS)与自由空间中目标强度(TS)差别很小。而像圆锥形这类目标的等效目标强度与自由空间中目标强度差别较大,导致传统的声呐方程误差较大。与波动声学方法相比,射线声学方法不但具有明确的物理意义,而且可以对浅海信道中复杂形状目标回声进行计算。
A ray acoustics method based on virtual source method and physical acoustic method for calculating target echo in shallow sea waveguides was established. There are an infinite number of multiple reflections of the incident sound ray through two interfaces, and each incident sound ray is reflected by the target and an infinite number of sound rays reaching the receiving point are generated. The combined echo fields are summed to obtain the total echo field. By using the ray acoustics method, the change of the echo of the absolute soft sphere with radius of 10 m in Pekeris waveguide with distance was calculated. Comparing with the calculation results of the wave acoustic method in the existing literature, the two are in agreement with the average and the downward trend. The calculated results show that there is little difference between the equivalent target intensity (ETS) and the target intensity (TS) in the free space of the waveguide and some circular targets. However, the equivalent target intensities such as conic are quite different from the target intensities in free space, resulting in large errors in the traditional sonar equations. Compared with the wave-acoustic method, the ray-acoustic method not only has a clear physical meaning, but also can calculate the echo of a complex shape target in a shallow sea channel.