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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。
The optical structure of the transmitting and receiving devices is used to measure the scattering of the 532 nm laser beam in the scattering angle of 5 ° ~ 175 ° with the wake of the bubble and the laser scattering of water is also measured. The change of the scattering angle is realized by rotating the receiving system by the transmitting system. The problem of compressing the large dynamic range of the scattering signal is solved, and the variation of the scattering volume with the scattering angle in the receiving field of view is discussed. The signal characteristics of bubble scattering were analyzed, and the power spectral density method of bubble scattering signal was proposed. The experimental results are compared with the results of Mie theory. It is found that the laser scattering intensity and the variation trend with the scattering angle of the wake bubble agree well with the Mie theory, and are nearly an order of magnitude different from the scattering of water. The results show that the use of laser can be bubble and water scattering can be distinguished, that the use of laser to detect the existence of wake bubble is feasible.