Predicting Turbine Performance of High Specific Speed Pumps Using CFD

A pump with a specific speed of 12000 was chosen to operate as a turbine (PAT) for a micro-hydro site having 5 m of head. Turbine performance of the pump was unavailable so it was simulated using CFD. The CFD model was first verified by comparison of simulated pump performance and manufacturer data. Simulated PAT performance covered a range of flow rates, from one to three times that of pump best efficiency point (BEP), for blade angles of 0 and ± 4°. The PAT BEP was located at a flow rate of 1.4 times that of pump BEP and a head of 1.6 times. For the specific site this corresponded to a shaft power of 32 k W and a flow rate of 770 1/s. The PAT was found to have an extended range of good efficiency, > 60%, for up to 3 times the pump BEP flow rate.