Study On The Motion Law And Wear Characteristics Of Particles In Centrifugal Pump Based On CFD-DEM

Centrifugal pump as a kind of general power machinery,widely used in the process of national production,and compared with the transport of a single medium,in the transport of solid substances,centrifugal pump internal flow conditions change,and a part of the liquid energy is used to transport solid substances,so the internal and external characteristics will be affected.In a long time of operation,the solid material will cause serious wear on the flow parts,which will lead to the change of the internal flow field and external characteristics of the centrifugal pump.Although the pump in the study of solid-liquid two-phase flow has a long history,and many scholars have conducted a lot of theoretical analysis,numerical calculation and experimental research work,but the inside of the centrifugal pump solid-liquid two-phase flow mechanism has not been very good revealed that centrifugal pump internal motion of solid particles is not clear,particle composition characteristics of centrifugal pump wear law also is not clear,therefore very necessary for centrifugal pump solid-liquid two-phase flow conditions to study the internal flow.For the numerical study of solid-liquid two-phase flow in centrifugal pumps,most of the previous studies used spherical particles with single size or single density,and did not consider the volume effect of particles,particle-particle,particle-fluid interaction,which is far from the engineering practice.Based on a specific speed centrifugal pump of n_s=93 as the research object,under the framework of the Euler-Lagrange CFD-DEM coupling method for centrifugal pump inside solid liquid two phase flow problems are numerically simulated,solid particles will adopt a multicomponent particle and multicomponent density particle diameter,study its inside a centrifugal pump wear properties of motion and flow components.Based on the inlet and outlet Angle of the impeller in the original model,the inlet Angle and outlet Angle of the blade were respectively changed to explore the influence of the change of the inlet and outlet Angle of the blade on wear.The research results are summarized as follows:(1)Under the multi-component diameter condition,large-diameter particles collide with the blade inside the impeller for many times and flow out close to the wall inside the volute,while small-diameter particles collide less in the impeller and move close to the inside of the wall,and the motion trajectory changes greatly after the collision.(2)The effects of particle diameter and density on particle motion are similar,and both of them are ultimately reflected by particle mass.For the design conditions,the distribution of small diameter particles in the impeller is more uniform,while the distribution trend of large diameter particles near the blade working face is more obvious.Small diameter particles are evenly distributed along the axial direction of the vane wheel.The closer to the rear cover plate,the more large diameter particles.(3)With the increase of flow rate and rotating speed,the distribution of large diameter particles tends to spread to the back of the blade.The distribution of liquid in the impeller is close to the blade profile.However,there is a great difference between particle velocity and fluid velocity,and there is a large Angle between the impeller and the blade working face.(4)Different shapes of particles have the same wear sites on the flow parts,while spherical particles have the least wear on the wall surface.The wear sites are mainly concentrated on the blade head,the outlet of the working face,the back cover near the impeller head,the volute tongue and the maximum radius of the outer wall surface of the volute.(5)Under the condition of different particle size proportions in the same inlet mass flow particles,the wear parts are basically the same,but the larger the proportion of large diameter particles,the more serious the wear on the flow parts,and the wear area is expanded.(6)Changing the inlet and outlet Angle of the blade will affect the external characteristics and wear of the centrifugal pump.