Experimental and numerical studies of liquid-liquid slug flows in micro channels with Y-junction inlets

The immiscible liquid-liquid two-phase flows in microchannels with 4 different inlet angles (30°, 60°, 90°, 120°) were analyzed using numerical and experimental methods. Silicone oil was used as the discrete phase, and distilled water containing 0.5 wt% SDS was used as the continuous phase. The influences of two-phase flow rates and inlet angles on droplet lengths were analyzed in detail. The two-phase pressure and the velocity vectors of the continuous phase vary periodically during the formation of droplets. Droplet length increases with increasing volume flow rate of the dispersed phase and the ratio of the volume flow rate of the dispersed phase to the continuous phase, and decreases with increasing volume flow rate and capillary number of the continuous phase. The smallest droplets are generated with 60° inlet angle at the same flow rate. Based on the multiple regression analysis, the correlation equation for the prediction of dimensionless droplet length was proposed using the ratio of dispersed phase to continuous phase volume flow rate, the capillary number of continuous phase and the inlet angle as parameters.