竖直弯管中含固体颗粒分散泡状流冲蚀预测

目的研究竖直弯管在含固体颗粒分散泡状流下的冲蚀规律,探究管内气液分布、颗粒分布及三维冲蚀形貌之间的关系。方法提出基于VOF模型和DPM模型的瞬态冲蚀数值计算方法,利用Oka等人提出的冲蚀模型及Grant和Tabakoff提出的颗粒-壁面碰撞模型计算管壁冲蚀速率。结果基于VOF和DPM模型的CFD冲蚀计算结果与经验模型及简化CFD模型的计算结果相比,更接近实验值。分散泡状流中,固体颗粒大部分分散在液相中,管道不同截面处的含液率与颗粒粒含量相关性较大,下游直管段和弯头处固体颗粒的粒含量大于上游直管段。含固体颗粒弯管在分散泡状流作用下,冲蚀区域较大,冲蚀最严重位置出现在弯头出口处附近。结论含砂分散泡状流冲蚀条件下,竖直弯管冲蚀形貌与管内气液固分布直接相关,多相流冲蚀瞬态仿真方法可较准确计算气液固分布并预测管道冲蚀。

Numerical Predictions of Solid Particle Erosion of Vertical Pipe Bend under Dispersed Bubble Flow

The work aims to investigate the erosion regularities of solid particles in the pipe bend under dispersed bubble flow and study the relationship among the gas-liquid distribution, solid particles trajectories and 3D erosion morphology. A transient state erosion simulation method based on VOF model and DPM model was proposed to calculate the erosion rate of pipe wall by the erosion model proposed by Oka et al. and the particle-wall rebound model proposed by Grant and Tabakoff. The results calculated by the CFD erosion model based on the VOF model and DPM model models were closer to the experimental value than those by the empirical model and the simplified CFD model. In dispersed bubble flow, solid particles were mostly dispersed in liquid phase. The liquid holdup in different cross sections had a close correlation with mass concentration of particles. The mass concentration of particles in the downstream straight pipe and in the elbow was higher than that in the upstream straight pipe. The area of the severe erosion region around the pipe bend containing solid particles was relatively large. The serious erosion location occurred at the outlet of the elbow.The erosion morphology of the vertical pipe bend under dispersed bubble flow is directly related to the gas-liquid-solid distribution inside the pipe. Multiphase flow erosion transient simulation can accurately calculate the gas-liquid-solid distribution and predict pipe erosion.