Investigation of Multiphase Unsteady Flow in a Double-Channel Pump by CFD Simulation and PIV Measurement

The multiphase unsteady flow fields in a double-channel pump have been investigated both numerically and experimentally for the design condition and also off-design conditions. Three-dimensional, unsteady Reynolds-averaged Navier–Stokes equations are solved on high-quality unstructured tetrahedral mesh with the shear stress transport turbulence model by using the CFD code Fluent 6.4. Furthermore, PIV measurements are successfully conducted in the impeller, in order to capture the complex flow with abundant measurement data and to validate the CFD results. The main conclusions include: 1) The velocity field changes according to the blade orientation. When the impeller channel is near to the outlet of volute, the velocity distribution is relatively regular than when the impeller channel is far from the outlet of volute. 2) At the tongue of the volute, the fluid discharged from the impeller mixes with the re-circulating fluid in the volute, which contributes a lot to the impeller-volute interaction. 3) The pressure vibration in the volute is very obvious, pressure fluctuation on monitors far from the volute outlet is more obvious than those near to the volute outlet, and becomes stronger as drawing near the tongue. 4) The sand volume fraction distribution is extremely inhomogeneous in both impeller and volute. Particles mainly flow along the pressure surface and hub of the impeller; Particles mainly accumulate in the region near to the exit of volute, and the largest sand volume fraction is observed at the tongue. 5) Particle diameter has great influence on the particle distribution, and particles tend to accumulate on the pressure surface of the balde with the increase of particle diameter. 6) The total pressure difference of the pump declines with the increase of inlet sandy volume fraction or particle diameter. 7) PIV measurement results correspond well with the CFD simulation results, which in turn gives a good validation of the simulation accuracy. This work offers a good data set to develop the comprehension of the unsteady multiphase flow in the double-channel pump.