A numerical procedure for estimating the sand erosion of elbows in annular flow with the complete thickness distribution of the liquid film

摘要

A numerical procedure is carried out to forecast the penetration rates of metal elbows caused by silica sand particles under air-water annular flow conditions. The procedure aims at overcoming the disadvantage of the existing numerical methods, which oversimplified the thickness distribution of the liquid film flowing through the elbows. The numerical procedure contains the steps of solving the flow field, tracking the particle response and calculating the collision damage. The core mixture in the pipe is taken as one homogeneous phase when solving the flow field. The drag force and turbulent dispersion force are calculated when tracking the particles in the core region. When tracking the particles in the liquid film, the specific film thickness at every given position of the elbow is introduced into the calculation. After calculating the particle-wall impact information, the penetration rate of the elbow is obtained by introducing the correlation which can calculate the collision damage of various metal materials. The numerical procedure is verified through the comparison between the typical experimental data and the predicted results. Several empirical and semi-empirical erosion prediction models are compared with the present procedure on the accuracy. The effects of the main factors on the penetration rate are investigated in the parametric studies. The thickness distribution and velocity of the liquid film considerably influence the effective collision intensity of the particles. By using the complete thickness information of the liquid film, the present procedure shows good accuracy in estimating the erosion of elbows under annular flow conditions.