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中文核心期刊

Y型微通道两相流内部流动特性

TWO-PHASE FLOW CHARACTERISTICS IN Y-JUNCTION MICROCHANNEL

  • 摘要: 利用显微粒子图像测速技术、高速度数码显微系统及数值模拟方法研究了Y 型微通道内液滴的形成. 主要考虑了Y 型角度(45°,90°,135°,180°)、两相流量大小等因素的影响. 发现在挤压机制中,Y 型微通道内分散相液滴的形成主要受到来自连续相的剪切作用,Y 型角度越小,分散相所受到的剪切作用越大. 在液滴生成过程中,连续相速度剖面呈非对称抛物线型分布. 当Y 型角度小于180°时,角度的变化对液滴直径大小影响较小,但角度的减小会加快液滴的生成时间. 当Y 型角度为180°时,生成的液滴体积最大且生成时间最长. 毛细数对液滴直径和生成时间的变化同时产生影响,连续相毛细数的增大使得连续相在两相交汇位置处对分散相的作用力更集中,导致分散相更易破裂.

     

    Abstract: Droplets formed in different Y-angles (45°, 90°, 135°, 180°) and flow flux of two-phase in Y-junction microchannels are studied by making use of micro-PIV, high speed digital microscopic system and numerical simulation in this paper. It is found that the shearing action impels the formation of dispersed phase droplet in the squeezing mechanism, and the smaller Y-angle results in the bigger shearing action suffered by dispersed phase. The continuous phase velocity profile is asymmetric parabolic distribution in droplet generation process. When Y-angle is less than 180°, it does not affect the droplet diameter size but will speed up the droplet generation as it decreases. The droplet size and generated cycle will be the largest in the case of Y-angle being 180°. It is indicated that Capillary number affects droplet size and generation time simultaneously. The increasing capillary number of continuous phase will make the acting force from continuous phase to dispersed phase more intensive in the junction of the two phases in the in-plane velocities in the continuous phase and lead to dispersed droplet rupture more easily.

     

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