微细圆管及扁平管内液-液Taylor流动特性的数值研究

微细通道内Taylor流动广泛应用于能源化工领域，为分析其相界面及阻力特性，利用相对坐标系的方法，研究了竖直圆管及扁平管内的液-液Taylor流动，讨论了通道宽高比、Reynolds数（Re）及分散相体积分数对液膜厚度和两相压降的影响。结果表明：圆管内液滴头部和尾部可以膨胀至近似球形，而扁平管内壁面的限制作用较强，液滴呈现扁平状。随Reynolds数增大，两相界面逐渐收缩，液膜厚度逐渐上升。圆管内液膜厚度比较均匀，扁平管内液膜在通道顶部较薄，而圆弧部分较厚。两相压降随Re和宽高比的增大而增大，随分散相体积分数的增大而降低。相比连续相和分散相压降，界面压降所占的比重最高，并依据模拟结果，提出了圆管及扁平管内液-液Taylor流动的压降预测公式。

Flow characteristics of liquid-liquid Taylor flow in mini channels with circular and flat cross-sections:a numerical study

Taylor flows in mini tubes have been widely adopted in energy and chemical industrials. In order to study characteristics of two-phase interfaces and frictional pressure drops, the liquid-liquid Taylor flow in mini channels with circular and flat cross sections are studied numerically using the moving frame reference method. Effects of Reynolds number, ratio of width to height, and volume fraction of the dispersed phase on two-phase interfaces, liquid film thickness, and pressure drops are analyzed. The numerical results show that the dispersed droplets in circular tubes are consist of spherical nose and tail. The dispersed flows in flat tubes are confined by the channel wall, leading to flat droplets. The two-phase interfaces shrink with increasing Re for all tubes, leading to a higher liquid film thickness between interfaces and channel walls at a higher Re. The liquid film thickness is uniformly distributed along the circumferential direction in circular tubes, while the liquid film in flat tube is much thinner at the flattened part compared with the arc corner. Two-phase pressure drops increase with increasing Re and ratio of width to height, while they decrease with increase in droplet volume fraction. Three components contribute to the two-phase pressure drops, which are the continuous pressure drop, the dispersed pressure drop, and the interfacial pressure drops. Compared with the other two, the interfacial pressure drop contributes more to the total pressure drop. A new correlation to predict the pressure drops in circular and flat tubes is developed.