An optical measurement system and video camera were used to investigate gas-liquid two-phase flow characteristics in a circular microchannel of 100 μm diameter. By cross correlating the signals from two pairs of optical fibers and infrared photodiodes, void fraction and the lengths and velocities of gas slugs and liquid slugs were measured. The data were obtained using a T-junction with the same internal diameter as the microchannel but the lengths of the gas and liquid injection lines between the T-junction and flow control valves were quite different. The presence of a large compressible gas volume upstream of the T-junction had a significant effect on the two-phase flow characteristics in the microchannel, typified by the void fraction data. The two-phase flow characteristics in the absence of a compressible gas volume were analysed to obtain the liquid slug length and velocity data. The liquid slug velocity was found to be dependent on the slug length, since longer slugs experienced greater friction effects and moved with much slower velocities than the shorter liquid slugs.
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