水下目标对幅度高斯相关海面环境噪声场扰动特性的研究

Perturbation characteristics of ambient sea noise field caused by submerged object

理论探讨了水下目标受海面环境噪声场激发产生的散射场对海洋环境噪声场的扰动特性,基于幅度高斯型相关海面噪声源模型,利用任意声源分布声场的积分表达式和单极子源半无限空间格林函数的球面波展开式,获得了刚性球目标在海面单极子和偶极子源海洋环境噪声"照射"下的直达噪声场、散射噪声场、总噪声场,以及二接收点直达、散射和总噪声协方差的理论表达式,表明总噪声场除了和目标阻抗特性、接收点的方向有关外,还受到海面噪声源相关特性,以及直达与散射噪声场之间干涉的较大影响。数值计算结果给出较近距离范围内,刚球目标声学可见度约为4～5dB,并指出在海洋环境噪声场中,刚球目标散射的方向特性明显不同于平面波入射。

Based on the source model with Gaussian-correlation amplitude, using the integral expressions for any source distribution and the spherical wave expression of Green function for a monopole in a half-infinite space, the perturbation characteristics of ambient sea noise field caused by scattering of the object is discussed theoretically. For a rigid spherical object under the irradiation of monopole and dipole sources, the expressions of direct-arrival noise field, scattering field, total field, and the covariance between the direct-arrival noise fields, the scattering noise fields and the total noise fields at two receivers are obtained, and the numerical results of scattering directional patterns of rigid spherical object and the visibility are given. It is shown that the total noise field is affected not only by the impedance characteristics of object, the direction of receiver, but also by the correlation between surface sources, and the interference between direct-arrival and scattering fields greatly. The results show that the sound visibility of rigid spherical object is about 4-5dB in near range and the scattering directivity characteristics of rigid spherical object under the irradiation of surface sources are different from plane wave incidence.