Droplet and bubble dispersion in step T-junction microchannel
【Abstract】A high-speed camera was used to study the dispersion of droplets and bubbles in a stepped T-junction microchannel embedded in a capillary. The effects of two-phase flow, viscosity, and surfactant on the flow pattern and the size of droplets and bubbles were investigated. The results show that for the droplet dispersion system, the flow pattern is determined by the concentration of the surfactant and the continuous-phase flow rate. The flow pattern changes from dripping flow to jetting flow as the two factors increase. For the bubble dispersion system, only the squeezing and dripping flow patterns exist. Addition of the surfactant has almost no effect on the bubble dispersion. The droplet and bubble size can be much smaller than the channel size. The mathematical models for predicting the dispersion size in different systems are established, and the models have good prediction performance.
【Keywords】 microchannels; microfluidics; multiphase flow; microdispersion; flow pattern;
(Translated by WANG YX)
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