水平分层低马赫数运动介质中的声传播

Sound propagation in low-Mach-number layered moving medium

针对海流对水声传播的影响,基于高斯波束追踪方法,利用高频近似的低马赫数亥姆霍兹方程,建立了三维低马赫数运动介质下的声传播模型,并将该模型应用于浅海与深海水平分层介质下的声传播问题。仿真结果表明,海流能定性定量地改变声传播模式。浅海环境下,声速梯度大于流速梯度,导致顺逆流声线反转点的差别随着距离增加而增大;此外声线到达结构也会发生较大改变。深海环境下,流速梯度大于声速梯度,顺流方向表面声道消失,使得表层顺逆流传播损失相差10 dB以上,同时水平分层环境中也会产生三维声传播效应。因此在流速梯度与声速梯度相当甚至更大时,海流对声传播的影响不能被忽略。

A three-dimensional sound propagation model in low Mach number moving media has been established based on the Gaussian beam tracing and the wave equation for high-frequency sound wave in a moving media with low Mach number.The model has been applied to horizontally layered medium in shallow and deep water.The simulation results show that ocean currents can qualitatively and quantitatively change the sound propagation mode.In shallow water,the sound speed gradient is greater than the flow velocity gradient,which results in the difference of convergence zone position of the upstream and downstream increasing with the propagation range,and the arrival structure of rays changing significantly.In deep water,the flow velocity gradient is greater than the sound speed gradient,causing the surface duct to disappear in the downstream direction,resulting in a difference of more than 10 dB in the propagation loss of the upstream and downstream.In addition,there is three-dimensional sound propagation effects in the horizontally layered environments caused by the currents.Therefore,while the flow velocity gradient is comparable to or greater than the sound speed gradient,the impact of ocean currents on sound propagation cannot be ignored.