Analysis of Unsteady Flow in a Radial Diffuser Pump

Three-dimensional, unsteady Reynolds-averaged Navier-Stokes equations are solved by the CFD code CFX-10 in a radial diffuser pump. The turbulence is simulated by the

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based shear stress transport turbulence model. To validate the CFD results, two-dimensional Laser Doppler Velocimetry (LDV) measurements have also been conducted. Both the phase-averaged velocity field and the turbulence field have been analyzed in detail. A comparison of the phase averaged velocity fields at the radial gap for both methods shows a very good agreement for the global periodic flow field. The analysis shows that a jet-wake structure is observed near the impeller outlet, and the diffuser flow strongly depends on the relative impeller positions which provide different inflow conditions for the downstream diffuser. The effects from the impeller rotation to the diffuser flow become very small at the diffuser outlet.