CFD Simulation of Turbulent Flow Structure in Stratified Gas/Liquid Flow and Validation with Experimental Data

Abstract

Abstract Although two-phase stratified flow pattern commonly occurs in petroleum industry the understanding of it, in terms of structure of the wave interface and the ensuing interaction between the two phases, is limited compared to single phase flow. Also, most of the studies have not taken the velocity profile across the pipe cross-section into account, rather just focused on the average velocity of each cross section. This paper will provide a unique insight into these velocity profiles, which are critical for frictional pressure drop calculations and prediction of phenomena such as wall effects of multiphase flow, erosion, corrosion, hydrate formation, wax deposition, etc. The objective of this paper is the analysis of this gas-liquid flow pattern in a horizontal pipe utilizing Computational Fluid Dynamics (CFD) simulation and comparison of the results with experimental data. The scope also includes the investigation of turbulent flow structure beneath gas-liquid interface by calculating the stream-wise velocity profile. Experimental studies have been conducted to investigate gas-liquid stratified flow in horizontal pipe. A unique experimental facility was constructed with a 4-in ID PVC pipe and measurements were performed utilizing air-water. Liquid level at the center of the pipe is measured by ultrasonic proximity sensor at different superficial velocities of gas and liquid. Along with experimental tests, CFD simulations for the same test conditions have been performed using a commercial CFD code. For tracking the two-phase interface, Volume of Fluid (VOF) method was applied. The numerical simulation was obtained with the Realizable k-epsilon model of turbulence. Comparing the CFD simulation results and liquid hold up measured experimentally revealed a good agreement (discrepancy<±15%). The experimental data also show that at constant superficial liquid velocities, the liquid level increases with decreasing superficial gas velocities. The validation of the CFD results with experimental data indicates that, CFD simulation has the potential to be used for facility design and scale-up processes in petroleum industry.