Research On Flow And Wear Characteristics Of Dense Fine Particles Solid-liquid Two-phase Flow In Centrifugal Pump

The main function of centrifugal pump is to transport fluid,and it is widely used in industrial production and daily life.When transporting fluid,there are solid particles in the pump,and changes in particle characteristics will not only lead to changes in the performance of the centrifugal pump,but also lead to changes in the wear of overcurrent components in the pump.Therefore,it is important significance to research the effect of particle characteristics on the performance and wear of centrifugal pump for the improvement of pump transport capacity and structure optimization.In this manuscript,the hydraulic model of centrifugal pump was established,and Euler multiphase flow and RNG k-ε turbulent model was used to simulate the flow of particles in the centrifugal pump on steady or transient state,respectively.The distribution of pump pressure and particle concentration under different conditions of the solid phase particle size(0.05 mm,0.10 mm,0.18 mm,0.30 mm)and volume fractions(10 %,20 %,30 %,40 %)and analyzed.The external characteristics of the centrifugal pump was measured by the flow experiment platform,and the effect of the characteristics of the solid particles on the external characteristics of the centrifugal pump was discussed.Then,a wear model was added to dense discrete phase model to simulate the transient flow in the pump,and research the position and rate of the wear in the pump when the solid particle characteristics was changed.Selecting Euler multiphase mixture model and sliding grid model simulate the transient state flow in the pump.The changes of flow field in pump with different particle size and volume fraction was analyzed.It was found that when the particle size increased,the flow performance of fluid decreased and the distribution uniformity of particle concentration decreased in the pump.The particles migrated from the backside to the working side of blades in the impeller passage.The particle concentration in the area near the wall of the volute increased.When the particle volume concentration increases,the particle concentration in the pump increases,while the position distribution of particles is nearly unchanged.The external characteristic was obtained based on the steady state simulation on the centrifugal pump model.Combining with the solid-liquid two-phase flow experiment of pump,the external characteristic under the conditions of different particle size,volume fraction was furtherly analyzed.The results indicates that when the particle size,volume fraction increases,the pump hydraulic and efficiency is lower,the deviation between simulated results and experimental results increases.The dense discrete phase model(DDPM)was used to simulate the transient wear of the centrifugal pump and the wear on the flow components under different particle characteristics was analyzed.It was found that the wear degree on the back side of the blade and the side near the back side of the front shroud decreases with the size of particles increases,while the wear degree on the head of the working face and the side near the head of the front shroud increases.When the volume fraction increases,the wear location of the centrifugal pump components has no effect and the wear rate increases.The particles enter the impeller passage first collide with the impeller head,then,part of them rebound to the back of the blade,another part flow out along the passage.There are backflow particles locates at the tongue.