模拟孔喉构型变径通道中微气泡流动特性研究

为了了解微泡沫驱中微气泡在多孔介质中的渗流特性，设计制作了一种集成T型通道和变径通道的微流控芯片，采用基于显微成像的微流控系统观察了液相分别为去离子水和0.02%吐温20水溶液时，微气泡在变径通道内的流动特性，并采用CFD方法分析了微气泡融合、变形过程中速度和压力变化情况。研究结果表明，以去离子水为液相时，随着气体压力和液相流速的变化，微气泡在流经变径通道时出现融合和不融合两种行为；以0.02%吐温20水溶液为液相时，微气泡在流经变径通道时会依次通过；微气泡在“喉—孔”处融合时，表面张力促使微气泡变形导致周围流体速度波动较大，形成“涡流”；融合后的气泡再次进入“喉道”时，“孔道”内压力增大。本研究有助于进一步认识微泡沫驱的渗流特性及驱油机理。

Research on the Flow Characteristics of Micro-bubbles in a Simulated Pore Throat Channel

In order to study the percolation characteristics of microbubbles in porous media, a microfluidic chip integrated with T micro channel and reducing channel was designed. Flow characteristics of microbubbles formed by "deionized water + air" and "0.02% Tween 20 solution + air" were studied by microfluidic system based on micro imaging. The fluid velocity and pressure changes in the microchannel during bubble fusion were analyzed by CFD method. Experimental results show that when the liquid phase is deionized water, with the change of gas pressure and liquid velocity, the microbubbles will fuse and not fuse when they flow through the reducing channel. The microbubbles generated by "0.02% Tween 20 solution + air" will pass through the reducing channel in turn and will not fuse. When the microbubbles are fused, the surface tension causes the microbubbles to deform, which leads to the large fluctuation of the surrounding fluid velocity, forming velocity "eddy current". When entering the "throat" again, the pressure in the "pore" increases. The experimental study is helpful to further understand the percolation characteristics and displacement mechanism of micro foam flooding.