水平PDMS微通道内气-液弹状流特性观察

Experimental observation of slug flow in horizontal PDMS micro-channel

对以空气、甘油为工作流体在水平聚二甲基硅氧烷(polydimethylsiloxane,PDMS)微通道内产生的弹状流进行了可视化实验研究。实验结果表明,微通道中弹状流的气柱速度随着体积含气率增大而阶梯状减小。气柱长度在体积含气率小于0.06时几乎不发生变化;当体积含气率大于0.06时,随体积含气率的增大而呈线性增大。气柱间距随体积含气率的变化与气柱长度相反。气柱和微通道壁面之间存在稳定的薄液膜,当地薄液膜压力稳定,气柱流经当地时所造成的压力波动很小;当地静压随体积含气率的增大而减小。

An experimental investigation was conducted to explore two-phase flow and pressure characteristics in a horizontal PDMS micro-channel with a rectangular cross-section of 100 μm ×100 /μm. Pure glycerine and air were used as working fluids. The variation of slug velocity presents a scalariform form and the velocity suddenly declined at the transition points. When the volumetric void fraction is greater than 0.06, the length of slug linearly increase with the volumetric void fraction approximately, When the volumetric void fraction is smaller than 0.06, the distance between two slugs decrease rapidly. There is a steady thin liquid film between slug and wall, which makes the local pressure of the micro-channel very stable. The average local pressure exhibit a gradual decline with the increase of the volumetric void fraction.