单圆柱微通道内流动特性实验研究

Experimental study on flow characteristics in a microchannel with a single cylinder

采用Micro-PIV实验系统和压差测试系统,研究了含有单个微圆柱的通道内去离子水在10<Re<430范围内的流动特性,得到了通道不同高度流层的流线、无因次速度场、湍流强度分布以及压降。结果表明,微圆柱绕流的第一、第二临界Re分别在10和430左右;尾流区漩涡内流体存在垂直流动方向的速度,漩涡三维特征明显;当Re较低时,压降及漩涡长度随Re增加较为缓慢,黏性阻力所占的比重较大,随着Re的增加漩涡发展,形状阻力占据的比重增加,压降随Re增加幅度上升,当Re达到400左右压降随Re变化曲线斜率增大,此时尾流区流动向着漩涡脱落过渡。

In this paper,a micro-PIV system and differential pressure measurement system is used to study the flow characteristics of deionized water in a channel with a single microcylinder in the range of 10<Re<430.The streamlines,dimensionless velocity field,turbulence intensity distribution of different flow layers,and pressure drop are obtained.Results show that the first and second critical Reynolds numbers of the flow around the microcylinder are approximately 10 and 430,respectively.The fluid in the wake vortex has a velocity component that is perpendicular to the flow direction,and the three-dimensional characteristics of the vortex are obvious.When Re is low,the pressure drop and the length of vortices increase slowly with Re and the viscous resistance accounts for a larger proportion.With increase in Re,the vortex gradually develops simultaneously with the increase in the proportion of shape resistance,and the pressure drop increases faster with Re.When Re=400,the slope of the pressure drop curve rises and then gradually transforms into vortex shedding.