Dynamics of Two-Phase Flows

ISBN Print: 0-8493-9925-4

CHARACTERISTIC STRUCTURE OF UPWARD BUBBLE FLOW

DOI: 10.1615/0-8493-9925-4.170
pages 359-377

Resumo

Structural characteristics of bubble flow were investigated by experimenting with nitrogen gas-water bubble flow in a square duct and a circular pipe using a laser Doppler anemometer and a double-sensor conductance probe system. Bubble size at constant gas and liquid flows was reduced by changing the gas injection method and by adding a surfactant to water. Coring, sliding, or uniform bubble flow occurred according to the bubble size. Results of the experiment show that each bubble flow exhibits characteristic behavior in the main flow; its turbulence and bubble motion depend on the size and distribution of bubbles. Moreover, it is found that coring bubble flow has a peculiar tendency for turbulence and that sliding bubble flow, with a specific saddle-type phase distribution, has turbulent suppression. Secondary flow in bubble flow exhibits essentially similar properties to that in single-phase flow, but its velocity tends to decrease in the region where bubble concentration is highest.