Influence of prewhirl angle on a centrifugal pump with inlet guide vane running at turbine mode

Abstract

The prewhirl regulation by inlet guide vanes (IGVs) has proved to be an effective method for optimal operation of the centrifugal pump. Pump as turbine (PAT) is a simple approach for small hydropower generation. The energy performance of centrifugal pump with IGVs running in turbine mode is investigated by numerical simulations under different prewhirl angles and flow rates. It is found that the best efficiency point (BEP) shifts towards large flow rate. The efficiency with GVs in turbine mode is slightly lower than that without GVs. The average efficiency decline is 0.46% with the appropriate prewhirl angle. With the installation of GVs, the shaft power is even somewhat improved, which indicates that PAT with GVs can recover the energy from fluid more effectively. The investigation of internal flow field shows an obvious vortex downstream GVs due to the strong rotation behind the impeller, and appropriate prewhril angle of GVs is helpful to reduce the vortices strength.