基于表面波纹特征的PIV明渠表面流速测量方法研究

Research on Surface Velocity Measurement Method of PIV Open Channel Based on Surface Corrugation Characteristics

在流场显示测量技术中,粒子图像测速(Particle Image Velocimetry,PIV)技术占有相当重要的地位。简要介绍了粒子图像测速的基本原理,提出了一种基于快速傅里叶变化(FFT)的互相关改进算法,以多帧连续互相关和窗口迭代缩小的方法,来实现互相关函数的运算,使得结果更加贴合实际、分辨率更高。首次提出了将测量监视图像与实际空间尺寸一一对应转换的全局标定法,结合改进后的算法,可在河渠场流速测算中得到较好的应用。计算所得流速场速度与实际水流流速的相对误差可保证在6%以内。

For the flow field display measurement technology,the particle image velocimetry technology occupies a very important position.The basic principle of particle image velocimetry is briefly introduced,and an improved cross-correlation algorithm based on fast Fourier transform(FFT)is proposed.The calculation of the cross-correlation function is realized by using the method of multi-frame continuous cross-correlation and window iterative reduction,and the result is more realistic and has a higher resolution.A global calibration method for the one-to-one conversion between the measurement monitoring image and the actual space size is proposed.Combined with the improved algorithm,it can be well applied in the flow velocity measurement of the canal field.The relative error between the calculated velocity field velocity and the actual flow velocity can be guaranteed to be within 6%.