Experiments and CFD simulations of erosion of a 90° elbow in liquid-dominated liquid-solid and dispersed-bubble-solid flows

Pipeline erosion in the production of oil and gas often occurs in elbows, tees, valves, pipes, chokes and other pipe geometries that cause a rapid change in flow direction. Liquid-dominated flows are of importance in mining and many oil fields and transportation lines carrying oil and gas including those in deep water subsea flowlines. In this study, experimental data for wall thickness losses were measured with an ultrasonic transducer in a 50.8 mm standard elbow. Experiments were conducted with multiphase flows with water, air and 300 µm average sand particles and with liquid-sand flows. Wall thickness losses were measured on the outer radius of elbows at 63 locations and for several different flow conditions. Computational Fluid Dynamics (CFD) simulation was performed using the Euler-Lagrange approach with the Reynolds Stress Model (RSM) for turbulence and Eulerian Multiphase model for multiphase flow cases. Different flow regimes were investigated in liquid-sand and multiphase flows. It was observed that maximum erosion increases as the mixture velocity increases. In addition, for liquid-sand and dispersed-bubble-sand flows the Euler-Lagrange and Euler-Euler-Lagrange approaches used in the CFD simulations were able to predict the observed maximum erosion rates, erosion locations and erosion patterns.