Analysis of Wave Field Composition and Characteristics in Shallow Sea
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摘要: 为更好地认识和利用浅海波导中的声场,该文对浅海中声源激发的波场成分及特性进行了研究。提出了能给出浅海中声场全波解的理论研究方法,给出了声场的复积分表达式,并在复平面上利用围道积分对声场复积分式进行求解,得出了浅海中声源激发出的声场组成部分;同时应用高阶交错网格有限差分法对浅海中声场进行数值模拟,呈现出了不同海水深度、声源频率和声源深度下浅海波导中的波场结构和空间能量分布。研究表明:浅海中声场由离散谱部分和连续谱部分组成;其中离散谱部分包括各阶简正波和Scholte波,连续谱部分包括侧面波;简正波和Scholte波的振幅与水平传播距离的开方成反比,而侧面波的振幅与水平传播距离的平方成反比;海水越浅、声源频率越小、声源深度越大,都会导致海水中的能量越少,越有利于Scholte波的激发,此时声源辐射的能量主要以Scholte波的形式传播出去,能量更多地集中在海底界面处。Abstract: To better understand and utilize the acoustic field in shallow sea, a theoretical method that can give the full-wave solution is proposed, then the complex integral expression of the acoustic field is given. The complex integral fraction is solved in the complex plane, and the components of the acoustic field in shallow sea are obtained. The high-order staggered grid finite difference method is also used to numerically simulate the acoustic field in shallow sea, showing the wave field structure and spatial energy distribution. Results show that the acoustic field in shallow sea includes discrete spectrum and continuous spectrum; The discrete spectrum includes normal waves and Scholte wave, and the continuous wave includes lateral waves; The amplitudes of normal waves and Scholte wave are inversely proportional to the root of horizontal propagation distance, and the amplitude of lateral wave is inversely proportional to the power of horizontal propagation distance; The shallower the sea water, the lower the frequency and the greater the depth of the sound source, the less energy in the sea water will be. The energy radiated by the acoustic source is mainly propagated in the form of Scholte wave, and the energy is mostly concentrated at the seabed interface.
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Key words:
- Shallow sea acoustic field /
- Full-wave solution /
- Discrete spectrum /
- Continuous spectrum
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表 1 浅海波导模型中的介质类型及其声学参数
介质类型 纵波速度cp(m/s) 横波速度cs(m/s) 密度ρ(kg/m3) 海水 1500 0 1000 砂岩海底 3500 1800 2300 -
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