应用单色光的三维激光测速系统

本文发展了一种采用单色激光器的三维激光测速系统。四束入射光布置成等腰直角三角形,用一个前透镜聚焦。这种光学布置光能利用率高,并能适用于近壁处流速测量。当实验模型具有多层不同性质介面时,入射光仍能保持相交。为了分离三维速度分量,采用了频率分离和偏振分离技术。特别考虑了光轴分量的测量精度,提出了提高测量精度的一些方法。应用此系统测量了斜切尾钝体后部的三维平均速度和湍流度分布。

A 3-D LASER DOPPLER VELOCIMETRY SYSTEM WITH THE SINGLE COLOR LASER

A 3-D LDV system for measuring three velocity components by using a He-Ne laser has been presented. Four incident beams were arranged to be an isosceles triangle with a right angle and focused by a single front lens. Such a beam arrangement has been examined as a most efficient form of the light energy utilization. It is also well suited to measure the velocity profiles close to a wall even in the situations in existing two different layers which the incident beams have to penetrate through, In order to separate the three velocity components, both the frequency and polarizing separation techniques were used. The accuracy of on-axis velocity component was particularly considered both for mean and turbulent velocity measurements. Some methods for improving the measured accuracy were suggested. The 3 D mean and turbulent velocity distributions behind a bluff body with a slanted base were also obtained simultaneously by using this system.