Analysis of sand erosion mechanism of horizontal pipe bend under dispersed bubble flow

The work aims to reveal the erosion mechanism of horizontal pipe bend under dispersed bubble flow. A gas-liquid-solid multiphase flow erosion experimental loop was constructed to study the flow state in the pipe bend and the three-dimensional erosion rate of the pipe bend. Microscopic analysis was used to study the erosion morphology of pipe bend. An erosion simulation method based on the coupling of VOF model and DPM model was proposed. Experiment and simulation were combined to analyze the influence of gas-liquid distribution and particle motion on the erosion morphology of the pipe bend. The most severe erosion area of the pipe bend appeared at the exit of the elbow (θ=90°), and the most severe erosion location occurred in the two positions of the section at φ=45° and φ=90°. The simulation results indicated that the edge of the sever erosion area showed a more uniform parabolic shape. The effect of sand on the pipe bend erosion was mainly based on impact deformation and micro-cutting friction. The direct impact collision of the sand caused dense erosion pits on the surface of the sample, and there were lips formed by the outward turning of the base material around the erosion pits. The solid particles in the dispersed bubble flow were mostly entrained in the liquid phase. The stagnation zone at the elbow made the cross-section liquid content and particle content of the cross section at the elbow larger than that at the cross section of the upstream and downstream straight pipes. The presence of gas changed the movement of the sand in the pipeline, greatly increasing the erosion of the pipe bend. The severe erosion area and erosion profile of the horizontal pipe bend under dispersed bubble flow are directly related to the gas-liquid distribution inside the pipeline and the sand movement. Multiphase flow erosion transient simulation can accurately predict pipeline erosion. © 2019, Chongqing Wujiu Periodicals Press. All rights reserved.