INVESTIGATION OF FLOW STRUCTURES IN VERTICAL SLUG FLOW

The flow structure of gas-liquid slug how in a vertical tube has been investigated experimentally and numerically. A photochromic dye activa tion method was used to obtain two-dimensional liquid velocity profile s around a Taylor Bubble rising in stagnant kerosene in a vertical 25. 6 mm I.D. pipe. A numerical simulation of the flow was conducted using a Volume-of-Fluid approach to predict both the shape of the Taylor Bu bble and the velocity profiles in the liquid phase. In order to test t he hypothesis that a trailing bubble can accelerate, catch up and coal esce with a leading bubble because of lateral motion and reduced drag force, a second experiment was performed using a solid Taylor Bubble p laced in a steady downward flow of liquid. The measured drag force sho wed significant reduction as the bubble was moved from the tube axis t owards the wall, giving support to the hypothesis. (C) 1997 Elsevier S cience S.A.