基于三维速度场构建的微流量测量方法研究

采用微流体粒子图像测速仪(microscale particle image velocimetry,micro-PIV)对200μm宽、60μm深的长直通道三维速度场进行了非接触定量可视化测量,并在此基础上计算了通道内的微流量。实验采用二维分层速度场测量方法,将通道沿物镜景深方向划分为11个流体层,通过高精度的位移平台实现流体跨层粒子图像采集。分别针对64×64像素和32×32像素2种判读域,采用micro-PIV系综相关算法对流体层二维速度场进行分析,获得三维全场速度分布,在此基础上利用截面速度离散积分原理计算出截面微流量。实验结果表明,基于微流体粒子图像测速仪的三维速度场分析能够实现对微通道流量的精确测量。对于64×64像素判读域,输入流量在2.481～5.788μL/min范围的测量结果精度较高,最大相对误差为3.87%;对于32×32像素判读域,输入流量在3.307～8.269μL/min范围内均有较高测量精度,最大相对误差为3.69%,表明采用32×32像素判读域的流量测量精度总体上优于64×64像素判读域。

Study on micro-flow rate measurement method based on construction of three-dimensional velocity

The microscale particle image velocimetry(micro-PIV) is used for the non-intrusive,quantitative and visualized measurement of 3D velocities in a straight microchannel of 200 μm width and 60μm depth.On this base the micro-flow rates in the microchannel are calculated.The measurement method of 2D velocities on the fluid layers is employed in this study;the flow in the microchannel is divided into 11 layers along the direction of the depth of field of microscopic objective.The particle images of various fluid layers are acquired with a high precision displacement platform.The micro-PIV ensemble cross-correlation algorithm is used to evaluate the 2D velocities in the interrogation windows of 64×64 pixels and 32×32pixels in various fluid layers;so the 3D velocities are obtained and the flow rate of the microchannel is calculated from the discrete integration of the velocity on the cross-section of the microchannel.Experiment results show that accurate flow rate measurement can be achieved using micro-PIV technique.For the interrogation windows of 64×64 pixels,the measurement precisions are good within the flow rate range between 2.481~5.788 μL/min and the maximum relative error is 3.87%;for the interrogation windows of 32×32 pixels,the measurement relative errors of 7 flow rates within the flow rate range between 3.307~8.269 μL/min have high precision and the maximum relative error is 3.69%,which indicates that the flow rate measurements in the interrogation windows of 32×32 pixels are better than that of 64×64 pixels.