尾流气泡激光散射的测量

Measurement on the Angular Scattering Properties of Wake Bubbles

采用收发分置的光学结构实现了尾流气泡对532 nm激光在散射角5°～175°内的散射测量,同时测量了水的激光散射。散射角度的改变是通过发射系统不动而转动接收系统来实现的。解决了散射信号大动态范围的压缩问题,讨论了接收视场内散射体积随散射角的变化。分析了气泡散射的信号特征,并提出了气泡散射信号的功率谱密度处理法。将实验结果与米氏理论结果进行了对比,发现尾流气泡的激光散射强度及其随散射角的变化趋势与米氏理论结果吻合得很好,与水的散射相差近一个数量级。研究结果表明利用激光可以将气泡和水的散射区别开,即利用激光探测尾流气泡的存在具有可行性。

Laser scattering by bubbles over a range of scattering angles from 5° to 175° is achieved using the bistatic optical geometry. In the meantime, laser scattering by water is measured. The scattering angle is changed by moving the receiving system on the condition that the transmitting ,system is fixed. The compress of the large dynamic range for the bubble scattering signal is solved and the change of the scattering volume with scattering angles in the receiver＇ s field of view is discussed. Then, the characteristics of the bubble scattering signal are analyzed and the power spectral density estimation method is put forward to process this signal. The experimentally measured and theoretically calculated results are compared, which show that both results are agreed and bubble scattering is about one order of magnitude higher than water scattering without bubbles. Results indicate that bubble scattering can be distinguished from water scattering, and thus bubbles can be detected by laser.