舰船尾流气泡层散射相位函数及其后向散射信号特性分析

Analysis of Scattering Phase Function and Backscattering Signal Characteristic of Bubble Films in Ship Wake

根据实测舰船的尾流气泡分布模型,利用米氏理论计算得到尾流气泡层的散射相位函数,并将其应用于尾流气泡层后向散射光接收信号的Monte Carlo仿真分析中,以便为实际海况下的舰船尾流气泡层后向散射光探测的实验设置与信号预测、分析提供可靠的依据。通过对不同距离处尾流气泡层的散射相位函数及后向散射光接收信号特性的分析,可以得出:尾流中气泡层散射相位函数的变化不明显,且对接收信号的影响较小;气泡数密度的变化导致的多次散射效应和气泡层衰减系数的变化是引起后向散射光强度变化的主要原因,数密度越大,散射光信号中的多次散射光成分越大;当气泡层厚度达到一定倍数的衰减长度时,继续增加气泡层厚度对后向散射接收信号的影响较小。

Scattering phase function of wake bubble films is obtained based on Mie theory and the distribution model of ship wake bubbles. Using the function the backscattering signal of bubble films is simulated by Monte Carlo method, which is useful to detect and analyze the backscattering signals of ship bubble wakes in situ measurement. The analyzsis of the scattering phase function and the backscattering signal characteristic in different regions of ship wake, shows scattering phase functions of bubble films in different wake region change little and affect the signal tinily; the variety of bubble density which causes the variety of multiple scattering and the bubble attenuation coefficient is the dominating reason influencing the backscattering intensity. Multiple scattering intensity becomes stronger when the bubble film is thick. When the thickness of bubble film is larger than a given times of attenuation length, the backscattering signal changes little with the increase of bubble film thickness.