浅海负跃层波导中声场仰角特性分析
Characteristics of the elevation angle in shallow-water negative thermocline waveguide
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摘要: 浅海负跃层波导中各阶垂直波数随深度变化, 基于等声速波导构建的模态仰角结构模型不再适用。为此根据波束位移射线简正波理论构建了适用于浅海负跃层波导的模态仰角结构模型, 并给出了声场仰角的分布特性。浅源声场仰角结构的峰值分布在自由模态区域, 深源相应的峰值分布在陷波模态区域; 声场仰角结构分布的集中程度随频率的增加而增加; 声场仰角结构的峰值位置随距离变化较小。仿真及海试数据处理结果验证了上述规律, 并利用海试数据验证了声场仰角特性用于目标分类的可靠性。Abstract: The modal elevation angle structure model constructed based on the Pekeris waveguides is no longer applicable since the vertical wavenumber varies with depth in the negative thermocline waveguide. According to the beam-displacement ray-mode theory, a modal elevation angle structure model suitable for the shallow water with a negative thermocline is constructed. The distribution characteristics of the elevation angle are revealed based on the model. The peak of the elevation angle structure for the surface source sound field is in the free mode region, while it is in the trapped mode region for the submerged source. The concentration of elevation angle structure distribution increases along with the frequency, while the peak position of the elevation angle structure hardly varies with range. These conclusions are verified by the simulation and sea trial results. The reliability of using elevation angle characteristics for target classification is confirmed using sea trial data.