Simulations of air-water two-phase flow in an inclined pipe

Abstract

Flow patterns depend on the mass flux and phase composition of the flow and also on the inclination angle of the tube. This work analyses the different flow patterns taking place in an inclined tube at 30 numerically. Both upward and downward flows are considered. The simulations of air-water flow in a pipe of diameter 0:051m and length 2m have been carried out using one-fluid model. The simulated flow patterns are slug, plug, stratified and bubbly flow. The calculated flow regimes are compared with data taken from the well-known Barnea flow pattern map. ANSYS-FLUENT 16.0 is used to solve the mass and momentum equations using second-order upwind scheme. The model takes into account the influence of gravitational force and the surface tension on the flow. A piecewise linear interface reconstruction based on Youngs's VOF is used. The simulation is carried out for the following combinations of superficial air velocities and superficial water velocities of (0.05, 0.1), (1.0,0.5) and (0.5,9.0) at an inclination angle of 30 and of (1.0, 0.1), (12,5) and (1.0,8.0) at an inclination angle of 􀀀30 . The volume fraction is predicted. To the authors’ knowledge, it is the first time that air-water flow as predicted by Barnea flow pattern map is being reproduced numerically and used to validate the VOF method. The results from FLUENT are compared with the experimental data from the well-known Barnea flow pattern map. The model predictions showed good agreement with experimental data obtained at both angles of inclination.