| Centrifugal pump is the key equipment of hydraulic transportation.It is widely used in solid-liquid two-phase flow transportation in mining,chemical industry,metallurgy,electric power and other industries.The existence of solid particles not only affects the hydraulic performance of centrifugal pump,but also easily causes the erosion of the flow parts,which affects the service life of centrifugal pumps.In-depth study of the solid-liquid two-phase flow in the centrifugal pump and the erosion mechanism of particles on the flow parts are the key to solving the above problems.This article is funded by the "Six Talent Peak Project of Jiangsu Province"(ZBZZ-016),using computational fluid dynamics(CFD)and discrete element model(DEM)coupled calculation method,combined with Oka and Archard erosion model to calculate the elbow Internal solid-liquid two-phase flow and the erosion of wall beacause of particles.Based on this,the numerical calculation of the solid-liquid two-phase flow in the centrifugal pump was carried out,and the influence of the impeller structure parameters on the solid-liquid two-phase flow and the erosion of the flow parts was analyzed.Based on the response surface method,the efficiency and average erosion rate are taken as the optimization targets,and the inlet angles,outlet angles and wrap angles of the blades are optimized.The main work and results of this paper are as follows:1.Research status of domestic and foreign scholars on the solid-liquid two-phase flow characteristics and the erosion of flow parts in centrifugal pumps are summarized,the advantages and disadvantages of different multiphase flow models are compared,the advantages of DEM method for processing particles are analyzed,using the CFD-DEM coupling method to calculate the solid-liquid two-phase flow in the centrifugal pump is determined.2.Based on the CFD-DEM coupling method,the Oka erosion model and the Archard erosion model,the solid-liquid two-phase flow in the elbow is studied.Comparing the calculated results with the previous ones,it verifies the accuracy of the simulation method and erosion model used in this paper.3.Based on the CFD-DEM coupling method,the solid-liquid two-phase flow in a centrifugal pump with different impeller structure parameters is simulated.The influence of blade inlet angles,outlet angles and wrap angles on the flow field,particle distribution and motion trajectory,average erosion rate,and the contact force and number of contacts between the particles and the wall are obtained.The results show that:(1)When the outlet angle increases from 18° to 35°,the low-velocity area of the suction surface gradually decreases,resulting in a gradual decrease of low-velocity particles on the suction surface,which in turn reduces the area where the suction surface is severely eroded.(2)When the inlet angle increases from 10°～19° to 27°～35°,the low-velocity area of the suction surface gradually increases,resulting in a gradual increase of low-velocity particles gathered in the middle of the suction surface,which in turn causes the severely eroded area to extend from the middle of the suction surface to the inlet side.(3)When the wrap angle increases from 110° to 160°,the low-velocity area of the suction surface gradually decreases,resulting in the gradual decrease of low-velocity particles gathered in the middle of the suction surface,and the severely eroded area of the suction surface gradually decreases.4.In this paper,the average erosion rate and efficiency are the optimization goals,the blade inlet angle,outlet angle and wrap angle are determined as the optimization parameters for response surface test design,and CFD-DEM coupling simulation is performed on 17 design schemes.The optimal structural parameters of the impeller are obtained.After optimization,the efficiency of the model is increased by 1.5%,and the average erosion rate is reduced by 70%. |
