PIV血流场显示测速技术

Particle image velocimetry techniques used in blood flow field analysis

通过分析多普勒测速技术与粒子图像测速技术的区别,从一个新角度把PIV全流场测速技术应用于血液流场的研究中。用激光片光源照亮血流粒子场,再计算确定实验系统光学参数,以获得最佳流场图片。对流场分析常用的互相关算法进行改进,辅以曲面拟合和误差修正,获得了亚像素级的全流场速度的大小和方向,并进一步计算出血流场的涡量分布和剪切率分布。为了验证改进的算法,对日本视频协会提供的PIV-STD序列标准图像进行仿真计算和误差分析,与原算法相比其速度矢量图的误差降低了2个百分点,流场速度值的平均误差小于±1%。该结果表明文中建立的方法是有效的,并可推广用于其它的流场分析。

Through analyzing the difference between velocity detecting techniques based on Doppler principle and Particle Image Velocimetry (PIV), PIV full field velocity showing and diagnostic technology have been applied to study of blood flow field from a new aspect. The blood flow particle field is illuminated by a laser light sheet and optical parameters of the experimental system are selected to obtain the optimal flow field pictures. Through improving cross-correlation algorithm commonly used for analysis of flow field and curved surface fitting and error correction, the magnitude and direction of blood flow velocity with sub-pixel level is obtained. Vorticity distribution and stress rate distribution of blood flow field are further calculated. In order to demonstrate the improved algorithm, simulation and error analysis based on PIV-STD serial standard image provided by Nihon Video Association is carried out. Compared with the original algorithm, the error of speed vector diagram has been reduced by 2% and average speed error of flow field is less than 1%. The results show that the method proposed effective and can be extended to other flow field analysis.