Numerical Simulation And Optimization Design Of Solid-Liquid Two-Phase Flow In Fluoroplastic Centrifugal Pump

Fluoroplastics pump is an ideal corrosion-resistant chemical pump at present.Although it solves the problem of corrosive liquids in many industries,the rotor parts are made of fluoroplastics,when conveying solid-liquid two-phase media,the wear resistance is poor.In this paper,the efficiency and wear performance of fluoroplastics centrifugal pumps are taken as objective functions,the main geometric parameters of impellers are taken as independent variables,and the relationship between objective functions and significant factors is established by response surface method.The multiobjective optimization design of centrifugal pumps is carried out by genetic algorithm in the optimization toolbox of Matlab,so as to improve the comprehensive performance of fluoroplastics centrifugal pumps.The main research work and conclusions are as follows:(1)For fluoroplastics centrifugal pump,the suitable turbulence model,particle model and fluid calculation domain of solid-liquid two-phase flow were selected.According to the solid-liquid two-phase flow state and the interaction between phases in the flow field,the comprehensive forces acting on particles in the flow field are analyzed.Based on Navier-Stokes formula,the particle motion equation is obtained.The calculation model is determined to be Euler-Lagrange particle trajectory model,and the turbulence model is a realizable k-e model.The 3-D model of SJB300-250-400 fluoroplastics centrifugal pump is built by UG.The water domains are imported into ICEM for meshing.Then start the calculation after processing the interface mesh size of each domain and setting the boundary conditions.(2)The effects of different working conditions and physical properties of solid particles on the solid-liquid two-phase flow field in fluoroplastics centrifugal pump were systematically analyzed.According to different flow conditions,the influence of solid volume fraction and particle size on the distribution of pressure,solid concentration,slip velocity and resistance coefficient of blade surface was numerically simulated and analyzed.It was found that the change of particle size had little effect on the flow field inside the pump,and the external characteristics of the pump had no obvious change under different particle size.The wear resistance of impeller decreased with the increase of particle size.The research results show that the efficiency decreases with the increase of flow rate,and the change of volume fraction has little effect on the efficiency when the particle phase is sparse and the concentration is low.With the increase of solid volume fraction,the wear resistance of impeller decreases.Compared with different particle sizes,the change of volume fraction has little effect on the wear resistance of impeller surface.Optimizing the main geometric parameters of the impeller and improving the comprehensive performance of the fluoroplastic centrifugal pump.(3)A multi-objective optimization design method was proposed to optimize the main geometric parameters of the impeller and improve the comprehensive performance of the fluoroplastic centrifugal pump.Because of the many geometric parameters of the impeller,this paper firstly uses the PB test design method to determine the significant degree of influence of each parameter on the optimization index.Then,through the Taguchi method,the importance of the sub-significant factors to the optimization index is determined and the best combination of sub-significant factors is determined.Finally,The response surface method is used to establish the relationship between each objective function and significant factors,and the multi-objective function is unified by the genetic algorithm in Matlab toolbox to solve the optimal parameter combination of significant factors.The impeller is processed according to the optimization result.Experiment on the external characteristics of plastic two-phase flow pump.The research results show that the optimized fluoroplastic centrifugal pump efficiency is increased by 8.98%,the wear rate is decreased by 6.64%,and the expected optimization target is achieved.The research conclusions of this paper provide an important basis for the optimization design of large-scale fluoroplastic centrifugal pumps,and have certain hydraulic design reference value.