Abstract
Microscopic structure of forced-convective air-water two-phase flow was experimentally investigated. In the experiment, setting the flowrates of water and air at several values, bubbly and slug flows were realized in a vertical circular tube of 19.7mm I.D. The holdup sensor was used to measure the time variation of instantaneous cross-sectional area-averaged void fraction about 1m downstream from the two-phase mixer. The void data were analyzed by means of the discrete Fourier transformation (DFT). The analytical results showed that the change from bubbly to slug flows are rather continuous. It was considered that the bubble clusters formed in the transition regime between bubbly and slug flows play important role in the present experiments.
