一种二维瞬时粒子图像速度粒度同时测量的新技术

基于灰度统计判别原理,提出了一种可以对二维平面内粒子图像的速度和粒径实现实时同时测量的新技术.基于灰度统计判别的查询算法在运用自相关运算获得速度大小的同时,根据两次曝光粒子图像的能量差异判别记录顺序,解决了数字粒子图像测速(DPIV)中粒子图像运动方向的二义性问题.利用图像处理技术实现了对粒子图像粒径的同时测量.以模拟的DPIV粒子图像为研究对象,开发了相应的查询算法,编制了二维粒子图像速度粒度实时同测的相应软件,并利用模拟粒子图像对查询算法进行了单区域和全区域的分析检验.结果表明,灰度统计判别解决了方向二义性问题,查询算法能够很好地处理各种模拟粒子图像,查询软件能够实现二维粒子图像速度、粒度的同时测量,运算时间满足实时测量的需要.

A New Simultaneous Measuring Technique for the Velocity and Size of Planar Particle Image in Real-Time

Based on grey-scale statistic classification,this paper presented a new simultaneous measuring technique for the velocity and size of planar particle image in real-time,called PIVS(Particle Image Velocimetry & Sizer).The velocity magnitude of particle images is determined by the similar auto-correlation operation,and the record time series of particle images is indicated by the energy difference between the two laser sheets.Therefore,the directional ambiguity is resolved by the grey-scale statistic classification inherently in a rather simple experimental system.The size of particle image is determined at the same time by image processing technique.The interrogation algorithm and its software were developed and tested by the simulated particle images of single interrogated cell as well as of full field.The results show that the method of grey-scale statistic classification of PIVS can solve the directional ambiguity.The interrogation algorithm can get high definition for all kinds of simulated images.The software works well and realizes the required functions of PIVS,and the relevant runtime can meet the demand of real-time operation.