Research On The Characteristics Of The Solid-liquid Two-phase Flow Of Coarse Particles In A Two-stage Mixed Flow Pump Based On The CFD-DEM Method

In the process of developing deep geothermal energy resources,the two-stage submersible pump as the main liquid lifting device will have more serious wear on the two-stage pump because the liquid to be transported contains sandstones of different sizes and shapes.Based on the CFD-DEM coupling method,the numerical model,calculation method and model setting are verified.Based on the model,the motion of particles in the two-stage mixed flow pump under different shapes and volume fractions is analyzed.By summarizing and summarizing the flow characteristics of the particles and the areas and forms that are more likely to collide with the impeller and the vanes,it provides theoretical support for the design of wear-resistant submersible pumps designed to transport coarse-grain two-phase flow.The main research work and innovations of this paper can be summarized as follows:(1)This paper summarizes the severe tests currently faced by geothermal energy development and the problems faced during the operation of geothermal pumps.In addition,by analyzing the theoretical results of domestic and foreign experts and scholars on the movement of solid-liquid two-phase flow in the pump,in view of the current research on the transportation of coarse particles in the pump and the research on the wear of the hydraulic components of the pump,the CFD-DEM coupling method is used to simulate the motion law of the coarse particles in the pump and the force on the hydraulic components.(2)In order to investigate the irregular shape and large particle size of the particles in the environment,the Euler-Lagrangian method is used to calculate the motion of solid-liquid two-phase flow,and gravity,buoyancy,drag,Magnus force,Safman lift force,collision between particles and the effects of particle spins are considered in the calculation of particle motion.(3)Based on the experimental results of gas-solid two-phase flow visualization,the results of the visualization of solid particles inside the centrifugal pump and the experimental results of the wear at the elbow,the feasibility of using the CFD-DEM method is simulated and verified.The accuracy of the motion and the accuracy of the wear in the pump arecompared with the experimental results,and the model parameters such as the reasonable dynamic domain calculation model and the simulation time step are obtained,and a suitable method for simulating the solid-liquid two-phase flow in the pump was established.(4)In this paper,the particle model with different shapes is constructed as the research object,and the motion law under different flow and particle volume fraction conditions is studied.In addition,by comparing and analyzing the difference of the force of different sphericity particles on the surface of the hydraulic components in the pump,the main reason of the force and distribution scale of the two-stage mixed flow pump is analyzed.(5)This paper studies the wear phenomenon of spherical particles on the first-stage hydraulic components of the two-stage pump,analyzes the main wear position,and summarizes the relationship between the wear position on the hydraulic components and its force,and proposes to reduce the hydraulic components.The cumulative force is used as an optimization goal to improve wear in the pump.In this paper,the CFD-DEM method is used to study the flow and wear characteristics of solid-liquid two-phase flow inside the two-stage mixed flow pump,which provides some reference and guidance for the development of high-efficiency and wear-resistant two-stage mixed flow pump.