Test And Numerical Simulation On Square Particles Solid-Liquid Two-Phase Flow In A Multistage Pump

As an important equipment for solid material transportation,solid-liquid twophase flow pump has been widely used in many fields,and the conveying medium is complex and diverse.Therefore,the research on solid-liquid two-phase flow in the pump has always been a research hotspot in the industry.At present,although scholars have made great progress in the research of solid-liquid two-phase flow in the pump,the related research mostly focuses non-spherical particles,and the research on solidliquid two-phase flow of on spherical particles in the pump is relatively scarce.In practical engineering,the particles in the solid-liquid two-phase flow in the pump are mostly non-spherical particles.Therefore,this paper takes square particles as an example to study the non-spherical particle-solid two-phase flow in the pump,and explores the movement characteristics of the square particles in the pump.The main work and results of this paper are as follows:1.This paper introduces the research progress in the design theory,test and numerical simulation of solid-liquid two-phase flow pump,and points out the shortcomings of solid-liquid two-phase research in the pump and the future development trend.2.The force types and calculation methods of particles in solid-liquid two-phase flow were analyzed,and the force differences between spherical and square particles were compared.The force balance equation and momentum equation are simplified by comparing the force level of particles.3.A solid-liquid two-phase flow test platform was built to test the energy performance of the pump under clear water condition and two-phase flow condition(spherical particles and square particles),and the energy performance changes of the pump when conveying spherical and square particles were analyzed.The test results indicate that: with the increase of particle volume and density,the head and efficiency of the pump show a gradually decreasing trend.The head and efficiency of the pump in spherical particle solid-liquid two-phase flow condition are lower than the corresponding water flow rate,and the maximum reduction are 0.32 m and 2.92%,respectively.The head and efficiency of the pump in square particle solid-liquid twophase flow condition are lower than the corresponding water flow rate,and the maximum reduction are 0.40 m and 3.18%,respectively.4.The high-speed photography test method was used to test the movement of spherical and square particles in the guide vane of the pump.The movement trajectory of the spherical and square particles in the guide vane was obtained,and the influence of particle shape on the movement trajectory and collision law of particles was analyzed.The test results indicate that:(1)The length of the particle trajectory in the guide vane is greatly affected by the position where the particle enters the guide vane.As the position of particles entering the guide vane approaches the back of the guide vane,the length of particle trajectory increases gradually.The trajectory of square particles in the guide vane is longer than that of spherical particles.(2)The particles mainly enter the guide vane channel from the back of the guide vane,and the proportion of square particles entering the guide vane from this position is higher than that of spherical particles.(3)The collision position between particles and guide vane is mainly concentrated in the guide vane head and guide vane working face,and the collision probability of square particles and guide vane head is lower than that of spherical particles.5.The square particles solid-liquid two-phase flow in the pump was numerically simulated by Fluent-EDEM coupling calculation,and the flow field and particle motion characteristics in the pump,as well as the particle velocity,position distribution and particle collision information were obtained.The numerical simulation results indicate that:(1)The velocity of square particles in the pump is mainly distributed in 1m/s ～6m/s.With the increase of particle density,the proportion of low velocity particles increases gradually,and the average velocity of particles decreases gradually.(2)The distribution of square particles at the impeller inlet is relatively uniform,and the velocity of particles flowing to the impeller outlet gradually increases and approaches the blade working face.The particles in the guide vane channel have the movement trend of the guide vane working face,and flow out along the working face after collision with the guide vane working face.(3)The collision of square particles in the pump mainly occurs between particles and particles and between particles and guide vanes.With the increase of particle density,the proportion of collision between particles gradually increases,and the proportion of collision with guide vanes gradually decreases.