| Research Abstract |
Air-water and steam-water two-phase flow characteristics have been observed visually using 20, 25, 50, 80 and 100 microns i. d. tubes made of either silica or quartz. The optical system used in the present work consists of a microscope magnifying the images up to 150 times, a high-speed video camera and a personal computer. The spatial resolution of the whole system was 0.4 microns. Following conclusions have been drawn from the present work.
1) More than several two-phase flow patterns were observed in micro-channels of diameter smaller than 100 microns, including bubbly, slug, Iiquid lump flows, Iiquid ring, annular film, and mist flows. Specifically, the liquid ring flow is one of our new findings.
2) It has been confirmed that surface conditions such as surface contamination and the wettability are dominant effects in two-phase flows in micro channels. A very interesting observation is That, in a very clean system both physically and chemically treated, several gas slugs were connected by a gas stem just like "Yakitori". We named this newly found two-phase flow pattern as skewered slug flow.
3) We proposed a two-phase flow pattern transition map for a 20-micron tube.
4) It has been confirmed that the cross-sectional average void fraction and pressure drop are well Correlated by the Armand correlation and the modified Chisholm correlation, respectively.
5) Based on our experimental observation and numerical simulation, we have proposed a bubble dynamic model taking into account two interaction forces exerting between the bubbles.
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