Abstract
Quasi-equilibrium radial position of a single bubble in turbulent upflow in a vertical tube were experimentally investigated. The liquid phase was water of several temperatures and the range of bubble size was 0.35-3.8mm. It was suggested that the bubble whose diameter is approximately smaller than 1mm is more probably located in the center part in the tube, while the bubble approximately larger than 1.5mm migrates towards the wall; we call these bubbles coring and sliding bubbles, respectively. The critical bubble size for the transition from coring to sliding bubbles increased with the increase of liquid flowrate but it was not significantly affected by the water temperature. A qualitative explanation in terms of lift force and drag force was given for these results.
