Analyses On Water Resistance For A Still Mixed-flow Pump Vaned Diffuser

Loss is inevitable when the energy is transferred by Mixed-flow pump. Therefore, in the special application environment, the high efficiency is required in the high dynamic of mixed-flow pump. Besides, the water resistance coefficient of mixed-flow pump is required as soon as possible when the pump is still.Mixed-flow pump with specific speed about500was taken for example in this article. The FLUENT software was adopted to simulate mixed-flow pump internal flow field distribution and water resistance coefficient changes in static state with establishing the time-averaged continuity equation with relative coordinates and the N-S equation for the flow channel, using standard k-ε equation with turbulence model, unstructured tetrahedral network and SIMPLE algorithm. And applying the principle of hydrodynamic, the flow channel of mixed-flow pump was simplified ordinary hydraulic piping. Use the friction loss formula to calculate pump water resistance coefficient with the existing hydraulic piping. Try to find out that the quantitative optimization for mixed-flow pump water resistance coefficient and the pump geometry parameters are directly related. Shows that:1The still mixed-flow pump vaned diffuser is in downtime, its water resistance coefficient is minimum, when the angle between outlet blade edge of impeller and inlet edge of vaned diffuser is22.5degrees. So this position is the finally position when the still mixed-flow pump vaned diffuser is in downtime.2When the mixed flow pump is shut in static state, under different working conditions of the flow of pump CFD analysis, found that the flow within the pump in the drag square zone, local resistance coefficient in the channel does not vary with flow Reynolds number change, only with the pump geometry size, and the hydraulic loss occurred mainly in the impeller and the guide vane body part two. The total water resistance coefficient of pump average under eight load cases is32.56, the average water resistance coefficient of the impeller blade19.35, average water resistance coefficient is16.23, the upper and lower floating value is2.3%.3According to the principle of fluid mechanics, the mixed flow pump impeller is simplified into a space elbow, calculate the water resistance coefficient of local resistance coefficient of the existing formula, and the calculated results were found with the numerical simulation results of difference, should according to increase its coefficient test value. It also shows that the flow of pump body is not a simple pipeline flow, hypothesis complexity and formula of the flow mechanism is not consistent, need to revise it.4The mixed-flow pump guide vanes to simplify the proposed two schemes, found simulation results close to the program calculation results and numerical calculation results, and plan two and the results of numerical calculation is large. So, not to guide vane flow passage and a water outlet pipe flow calculation of its water resistance, only two comprehensive consideration, can be located in the outlet pipe on the entrance section of uniform flow assumption is removed, which is closer to real flow guide vane body.