TWO-PHASE FLOW CHARACTERISTICS IN Y-JUNCTION MICROCHANNEL

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.