基于光流算法的粒子图像测速技术研究

光流测量技术作为一种新的空气动力学实验技术,以其像素级分辨率的矢量场测量优势获得广泛的应用。光流测量技术使用光流约束方程,配合平滑限定条件,可以进行速度场测量,获得高分辨率的全局矢量场。首先通过研究积分最小化光流测速理论和算法,采用C++编写光流速度测量程序,然后通过3种典型人工位移图像对光流计算程序进行验证,并将结果和标准位移分布进行比对分析,以指导如何在实际应用中获得高精度光流速度场,最后进行小型风洞后向台阶实验,利用高速相机拍摄示踪粒子图像,使用光流计算程序获得速度矢量场,同采用互相关算法的粒子图像测速计算结果进行比较,体现出光流计算方法像素级分辨率的矢量场测量优势。

Research on particle image velocimetry based on optical flow

As a new aerodynamics experimental technique,optical flow test technique gradual-ly attracts more and more attention due to its advantages in vector field measurement with pixel scale resolution and strong smoothness ability.By means of scalar constraint equation combined with smoothness constraint condition,optical flow test technique can measure global velocity vec-tor field with high space resolution.In this paper,the integration minimization optical flow ve-locimetry theory and algorithm were firstly studied and programmed by C++;then,in order to verify the accuracy of the optical flow algorithm,three groups of grayscale images shifted by giv-en displacements were used for processing by the optical flow algorithm program and the result can be used to guide how to obtain high-precision optical flow calculation result in the actual measurement applications;at last,backward step verification experiment,in which tracer parti-cle images were acquired by high speed camera and velocity vector field was calculated by optical flow algorithm,was completed in a small wind tunnel.The result calculated by optical flow algo-rithm was compared with the result calculated by PIV′s cross-correlation algorithm,which shows that optical flow test technique possesses the advantages of pixel scale resolution.