Numerical Simulation Of Solid-liquid Two-phase Flow And Wear Experiment Of Centrifugal Slurry Pump With Small Blades

Centrifugal slurry pump is often applied to conveying fluid containing a large number of solid particles,which is widely used in ore mining,metal smelting,petrochemical and other industry fields.During the operation of the slurry pump,the wear of impeller is the most serious,which will affect the normal operation of the pump system.To solve this problem,it is necessary to investigate the wear mechanism of slurry pump.The 25MZ centrifugal slurry pump was taken as the research object in this research,and the Euler-Euler multiphase flow model was used to study the influence of different impeller structures on the wear characteristic of the slurry pump.Based on the solid volume fraction and solid velocity,the wear condition of the flow components of the slurry pump was qualitatively analyzed.Finally,the accuracy of the numerical simulation results was verified by the experiment test.The main research work and conclusions are as follows:1.Based on the particle heterogeneous flow model originated from the Euler-Euler method,the internal flow characteristics of the impeller inlet section,impeller,and volute under the conditions of 0.6Q_BEP,1.0Q_BEP,and 1.5Q_BEPwas analyzed.The results show that the fluid in the inlet section of the impeller presents the prewhirl characteristics,and the direction of rotation is the same as that of the impeller.In the flow part,through the study of the solid volume fraction and solid velocity,it is found that with the increase of the flow rate,the area with the larger solid volume fraction on the pressure surface of the blade moves from the leading edge of the blade to the trailing edge of the blade.The area where the volume fraction of the solid phase on the wall of the volute is larger moves from the area close to the shroud of the volute to the area close to the hub.The head of the pump increases with the increase of the rotation speed,and decreases slowly and then rapidly with the increase of the volume concentration of the solid phase.Consequently,the corresponding head value can be reached by adjusting the pump speed at the working point,so as to reach the rated operating point of the slurry pump.2.The influence of different impeller structures on the hydraulic performance and wear characteristics of the slurry pump was analyzed by setting small blades at the outlet of the impeller hub.In the steady calculation,the pressure field,vortex structure,turbulent kinetic energy and entropy production were mainly studied.The results show that:under small flow conditions,obvious leading edge vortex and trailing edge vortex can be seen at the blade inlet and outlet.At the outlet of the impeller,the turbulent kinetic energy is larger.The flow loss inside the impeller mainly occurs at the inlet and outlet of the blade,which results in the entropy loss in this area.In unsteady calculations,it is found that small blades can suppress the diversion and outflow at the blade outlet,making the flow pattern inside the impeller more stable and the pressure fluctuation coefficient smaller.The radial force distribution of the impeller is quadrangular.3.In order to verify the correctness of the theoretical analysis and the accuracy of the numerical simulation results,the wear test of No.1 pump and No.2 pump was carried out,and the method of equal flow control and impeller weight loss measurement was used to study the wear of the impeller.The solid particles were brown corundum.The results show that the blade inlets of the No.1 and No.2 pumps were worn severely,and it was more obvious near the hub.The hub of the No.2impeller was worn out near the impeller inlet,and the failure was serious.The side of the blade outlet near the hub is severely worn.The main reason is that after the solid particles enter the impeller,they move toward the hub due to inertia force,resulting in serious abrasion at the junction of the impeller inlet and the hub.After the solid particles enter the impeller flow channel,the radial velocity and circumferential velocity of the particles gradually increase,and the solid velocity reaches the maximum at the blade outlet,so that the wear is serious.