次声波在非均匀运动大气中非线性传播特性的研究

基于有限时域差分方法将大气中近似到二阶的非线性波动方程进行离散化,得到了数值模拟所采用的差分方程. 在此基础上,对线阵列辐射的脉冲声波在非均匀运动大气中的垂直和斜向传播进行了二维数值模拟,模拟了武汉地区(114:20°E, 30:37°N)在夏季和冬季UT=29000 s时开始传播的脉冲声波在不同时刻的声压分布. 模拟时通过采用Msise00和HWM93 两个大气模型,考虑了由于大气温度和密度变化以及大气风场存在所引起的大气不均匀性和运动性. 通过研究上述两季有风与无风条件下的声压差值p_r,可以发现:风场对次声波在传播中声压分布的影响较大;由于不同季节和不同传播距离上"有效声速"的不同,导致了两季p_r分布波形存在差异;风场对声波非线性传播的影响要远大于其对线性传播的影响. 关键词： 次声波传播 非均匀运动大气 有效声速

Properties of infrasonic wave nonlinear propagation in the inhomogeneous moving atmosphere

A difference wave equation is obtained by discretizing a nonlinear acoustic wave equation in atmosphere in the second-order miniterm approximation based on the finite-difference time-domain method. And the pulsed infrasonic wave radiated by a linear array vertical or oblique propagation in moving inhomogeneous atmosphere is numerical simulated in the two-dimensional space, and sound pressure distribution after the different propagation times is investigated in the Wuhan(114 ∶20°E, 30 ∶37°N) of China and the initial time UT=29000s of summer and winter. The atmospheric inhomogeneity caused by the change of temperature and density, and the atmospheric motion caused by the presence of wind is considered by using the Msise00 and HWM93 models. The pressure difference p_r obtained by subtracting no-windy pressure from the windy-pressure in above two seasons indicates that the wind has more influence on the sound field in the infrasonic propagation. The distribution waveform of p_r is dependent on season because the "actual acoustic velocity" depends on season and propagation distance; The influence of wind on the nonlinear propagation is bigger than on the linear propagation.