CFD simulation of multiphase flows and erosion predictions under annular flow and low liquid loading conditions

Abstract

For many industrial applications dealing with gas-liquid flow, transporting gas and liquid simultaneously causes many challenges. Prediction of erosion in multiphase flow is a complex problem due to lack of accurate models for calculating particle impact velocities in multiphase flow. Computational Fluid Dynamics (CFD) studies of annular flow are being conducted to investigate annular flow behavior and particle impact characteristics. Volume of Fluid (VOF) method was employed for air-water flow simulation with high gas velocities and low liquid rates. Simulation results are compared with results obtained with Eulerian-Eulerian with Multi-Fluid VOF approach with the same flow rates. CFD simulations of annular flow were also compared and validated with experimental data previously obtained with wire-mesh sensors. The liquid film thickness in bends can significantly affect erosion, therefore the simulation results of liquid film thickness trends are also investigated based on the gas and liquid flow rates.Particle tracking along with flow simulations have been solved simultaneously, and the maximum values of mass removal calculated with current erosion models were recorded in order to calculate the maximum erosion magnitudes. Particle impact characteristics including particle impact velocities, particle impact angles as well as particle impact number distribution along the bend were studied in several cases with different superficial gas and liquid velocities. Predicted erosion ratios are compared with available experimental data and show very good agreement.