Numerical Calculation And Experimental Test On Solid-Liquid Two-Phase Flow In A Double Blade Pump

Solid-liquid two-phase flow pump are widely used in electric power, environmental protection, food and mining et al. Along with the development of deep-sea mining and reclamation island and other fields, the traditional research on fine particle solid-liquid two-phase has been unable to meet the design requirements of coarse particle pumping system. Therefore, it is necessary to strengthen the research on the fine particle solid-liquid two-phase flow in the pump, at the same time, carrying out the research on the coarse particle solid-liquid two-phase flow. So as to further enrich and improve the design method and theory of solid-liquid two-phase flow in the pump.In this paper, a specific speed ns =111 double blade sewage pump as the research object. The solid-liquid two-phase flow mechanism of fine particles and coarse particles in the pump were made in a comprehensive and systematic way. The particle properties influence on particle trajectory, particle distribution and the hydraulic performance of the pump were preliminarily revealed. In view of the advantages and disadvantages of numerical calculation and experimental test, in this paper, the CFD calculation method was used to study the fine particles solid-liquid two-phase flow in the pump and the motion of the coarse particles in the pump was studied by high-speed photography. The main research conclusions as below:1. The double blade pump, the numerical calculation of solid-liquid two-phase flow in pump and the experiment of coarse particles solid-liquid two-phase flow at home and abroad were concluded systematically.2. On the basis of force analysis of particles in double blade pump, kinematics equations of fine particles and coarse particles in the pump were established respectively, and the difference between the two equations were compared and analyzed.3. The unsteady solid-liquid two-phase flow in a double blade pump was numerically simulated by using combination of the standard k-ε turbulence model and the Mixture multiphase flow model.The influences of two-phase flow rate and particles properties, namely diameter, density and volume fraction, on the pressure fluctuation and radial force of a double blade pump were analyzed. The main conclusions are following:(1)The effect of the addition of particles on the pressure fluctuation is obvious. The average pressure pulsation of the volute circumference has an increasing trend with the increase of particle density or particle volume fraction.Selecting the appropriate particle size, appropriate particle density or appropriate particle volume fraction can contribute to weaken the pressure pulsation when transporting solid-liquid two-phase flow.(2)The peak value of the impeller radial force and the peak to peak radial force in solid-liquid two-phase flow condition are larger than that of the corresponding water flow rate,and the maximum increase are 7.82% and 8.21%, respectively.4.The synchronous test bench to measure hydrolic performance of the double blade pump and coarse particle motion was built.By using the test bench, the hydrolic performance, single particle motion, particle distribution, particle collision and particle through performance were test synchronously.The main conclusions are following:(1)The particle parameters have less influence on hydraulic performance of the double blade pump.(2)The larger the particle diameter or particle density, the tendency of the relative movement to the blade pressure surface is more obvious.(3)The particle group is mainly distributed near the blade pressure surface in the impeller, and the difference of the particle group distribution in each volute section is obviously.(4)The impact location of particle with density 1.09g/cm3 is mostly on the left side of the tongue, while impact location of particle with density 1.75g/cm3 is mainly on the top and the right side of the tongue.(5)With the increase of particle density, the average time of the particles pass through is gradually getting shorter. The time of the particles pass through has been shortened by 22.7% in the density increase process.