基于DDPM的螺旋离心泵磨蚀特性分析

Analysis of erosion characteristics of screw centrifugal pump based on DDPM

应用雷诺涡黏模型、DDPM(density discrete phase model,稠密离散相模型)及颗粒直径Rosin-Rammler分布方法,以黄河含沙水为介质,对一台100LN-7型螺旋离心泵内固液两相流动进行全三维数值模拟,并与基于Mixture混合多项流模型的泵内两相流动数值模拟结果进行对比分析,得到不同粒径和固相体积分数对应的泵过流部件的磨蚀规律及磨蚀强度.结果表明:颗粒混合状态不同会形成不同的粒径分布,混合粒径中平均粒径增大导致叶片进口边及工作面轮缘线附近磨蚀强度增大,平均粒径为1mm时整台泵过流部件磨蚀率达到最大值,平均粒径继续增大磨蚀率反而降低;固相体积分数的增大使整台泵过流部件的磨蚀强度显著提高,叶片背面较其他部位磨蚀强度大;Mixture模型下固相体积分数较高部位与稠密离散相模型下颗粒磨蚀部位相对应,局部区域存在较高体积分数的固相颗粒增加了过流部件表面发生磨蚀的几率,但DDPM模型数值模拟表明只有部分颗粒参与局部区域的塑性磨蚀.

Taking the Yellow River silt-laden water as medium and using Reynolds eddy viscosity model,dense discrete phase model(DDPM),and Rosin-Rammler particle size distribution method,the full threedimensional numerical simulation of solid-liquid two-phase flow in screw centrifugal pump was carried out and the result from Mixture model was compared with that from DDPM and analyzed.The erosion pattern and intensity of flow-passage components of pump was obtained for the case of different particle mean diameter and volume fraction.The result showed that various distribution of particle diameter might be formed due to the difference of Mixture condition and the erosion intensity at inlet edge of blade and near wheel edge line on pressure side of blade would achieve its increase with mean particle diameter of the mixture and erosion rate of all flow-passage components of the pump maximum in the case of the mean diameter being equal to one millimeter.Further increase of it would make the erosion rate decreased,instead.With the increase of solid-phase volume fraction,particle erosion intensity of all flow-passage components would rapidly grow and the key erosion position would be concentrated on suction side of blade.Highervolume-fraction position of solid-phase in Mixture double-fluid model would correspond to particle erosion position with high-volume-fraction in dense discrete phase model.The solid-phase particles with higher volume-fraction at local zone would make the probability of erosion generation on the surface of flow-passage components increased but only aportion of particles would be involved in the plastic erosion at local zone.