Prediction of Pump Performance as Turbine and Splitter Blades Effect

Pumps are used in reverse direction as hydraulic turbines due to their simple structure but use of a pump as a turbine changes its characteristics. In this study reverse operation of a centrifugal pump is numerically investigated so Best Efficiency Point (BEP) and performance diagrams are obtained. Splitter blades as a passive flow control were used in many turbo machineries and are suggested in this study for pumps as turbines. Governing equations including continuity and momentum equations were employed in time-averaged form due to turbulent behavior of flow. Source term of momentum equation was used to consider rotating effect of impeller such as Coriolis acceleration and centrifugal force. Proposed numerical method uses k-ω SST turbulent model with standard wall function .To simulate the flow in rotating and stationary parts of the turbo machine, Multi Reference Frame (MRF) analysis was employed along with Frozen Rotor technique. Results showed that efficiency was improved and BEP tends to occur at higher flow rates in splitter bladed impellers, which results in higher energy production. On the other hand cavitation risk is reduced by means of splitter blades.