颗粒形状对弯管冲蚀磨损影响的数值模拟研究

Numerical simulation research for the effect of particle shape on the erosion wear in elbow

为了研究输气管内不同形状固体颗粒对弯管冲蚀磨损特性的影响,预测弯管内壁受到冲击后磨损分布情况,采用计算流体动力学(CFD)来计算气体流动,采用离散单元法(DEM)来计算颗粒运动,其中非球形颗粒采用超椭球模型进行建模,并用切向撞击能量磨损模型(SIEM)来计算弯管磨损。模拟结果表明,在相同气速条件下,尽管不同形状颗粒在管中的运动状态差别不明显,但是对应的管道内壁磨损情况却有很大差异:颗粒越接近方形,造成的弯管最大磨损率越高,磨损严重范围也随之增大,但最大磨损率的位置会趋于稳定;弯管内长椭球颗粒发生滑动摩擦概率更高,扁椭球颗粒发生滚动摩擦的概率更高,这导致了长椭球颗粒对弯管总磨损率高于扁椭球。比较不同气速下颗粒形状对弯管磨损程度的影响,发现升高气速仅会均匀增大弯管磨损,最大冲蚀位置并不会改变。

In order to study the effect of solid particles of different shapes in the gas pipelines on the erosion wear characteristics of the elbow and predict the wear distribution of the inner wall of the elbow after being impacted,computational fluid dynamics(CFD)is used to calculate the gas flow.The discrete element method(DEM)is used to calculate the particle motion,and the non-spherical particles are described by the super-ellipsoids model.The shear impact energy model(SIEM)is used to calculate elbow wear.The simulation results show that,under the same gas velocity,although the difference of the movement of particles of different shapes in the elbow is not evident,the corresponding wear condition of the inner wall of the elbow is significantly different from each other:the closer the particle shape is to the square,the higher the maximum wear rate in the elbow,and the wider the range of serious wear.But the position of the maximum wear rate will tend to be stable.The probability of sliding friction of prolate ellipsoid particles in the elbow is higher,while the probability of rolling friction of oblate ellipsoid particles is higher,which causes the total wear rate of prolate ellipsoid particles on the elbow to be higher than that of the oblate ellipsoid.Comparing the influence of particle shape on the wear of the elbow under different gas velocities,it can be found that larger gas velocity only homogeneously increases the wear of the elbow and the maximum erosion zone will not change.