基于粒子图像叠加方法的微柱群绕流流场测量

Velocity measurements for flows around micro-cylinder array based on image overlapping

分析了相关深度对Micro-PIV速度场测量的影响,说明采用低密度粒子图像叠加技术能够有效减小相关深度,提高速度测量的准确性。将该方法应用于微柱群绕流流场的分层测量,雷诺数分别取0.8~3.6,在此基础上计算了空间平均速度。将分层速度场和平均速度廓线与采用平均相关技术获得的结果进行了比较。结果表明,采用低密度粒子图像叠加方法获得的全场绕流速度分布更为合理,通道底部和顶部近壁区的平均＂伪滑移速度＂分别减小了22.7%和17.2%,通道中心平均速度峰值增加了5.2%。

In this study,the influence of depth of correlation（DOC）on the micro-PIV measurement is analyzed.The method of image overlapping under the low particle density condition can decrease DOC and improve the velocity measurement accuracy.This method is applied to the velocity measurements on multiple fluid planes for the flow around a micro-cylinder array under eight Reynolds numbers from 0.8to 3.6,and the spatial averaged velocities（SAVs）are calculated based on the velocities.In order to analyze the measurement accuracy,the velocities and SAVs resulting from the method of image overlapping are compared to those obtained by the method of average cross-correlation.The results indicate that of the image overlapping is a more reasonable method under the low particle density condition.The average pseudo-slip velocity decreases by22.7%for the bottom surface and 17.2%for the top,respectively,and the average peak velocity increases by about 5.2%.