超声速光学头罩流场的PIV研究

在马赫数Ma-3．8超声速风洞中，采用PIV（Particle Image Velocimetry，粒子图像测速）技术测量了超声速光学头罩流场的速度分布。PIV技术应用于超声速流场时，对系统的硬件配备、示踪粒子的跟随性以及PIV算法的精度有很高的要求。本文PIV系统选用高精度的同步控制器和高能量激光器；以纳米级粒径的粒子作为示踪粒子，通过斜激波响应实验分析了其在超声速流场中的跟随性；并采用多种高精度速度场算法对粒子图像进行处理。实验结果表明，示踪粒子在超声速流场中有很好的跟随性，采用的高精度速度场算法能够很好地反映超声速光学头罩流场的速度分布。

PIV study of supersonic flow around an optical bow cap

Velocity field of supersonic optical bow cap was studied using PlV （Particle Image Velocimetry） in Ma=3.8 supersonic wind tunnel. The application of PIV to supersonic flow demands good performance of PIV hardware, fine flow-following ability of tracer particle and high accuracy of PIV algorithms. Synchronizer with high accuracy and high energy laser were chosen for the PIV system in this paper; tracer particle with diameter at nanometer scale was selected and its performance in supersonic flow was assessed through measurements of particle lag downstream of a two-dimensional oblique shock wave; several high-accuracy PIV algorithms were used for particle image processing. The results revealed that the tracer particle performed very well in supersonic flow, and the algorithms yielded the velocity field of the supersonic optical bow cap faithfully.