Improving Centrifugal Pump Performance under Low Flow Rates by Adding Designed Cylindrical Disks at the Impeller Inlet

Enhancing the performance of centrifugal pumps requires a thorough understanding of the internal flow. Flow simulation inside the pump can help understand the rotatory motion induced by the impellers, as well as the flow instabilities. The flow inside a centrifugal pump is three dimensional, disturbed and accompanied by tributary flow structures. When a centrifugal pump operates under low flow rates, a secondary flow known as recirculation starts to begin. The separation of flow occurs which creates vortices and decreases local pressure which induces cavitation. This phenomenon of recirculation will rise the Net Positive Suction Head Required (NPSHR). This work aims to improve the pump efficiency under low flow rates by adding multiple cylindrical disks at the pump inlet section to suppress the flow recirculation.

In this study, a numerical simulation is carried out to investigate the influence on the pump internal flow by adding multi cylindrical disks. The research presents the performance of seven different impeller designs, each consisting of two cylindrical disks at the impeller inlet. It is assumed that these modifications will help suppress the recirculation phenomenon. The turbulent flow within the centrifugal pump was analyzed by applying the κ-ϵ equations for turbulence modelling. The computational domain consists of the inlet, impeller, diffuser and outlet. Analysis of ΔP, torque and pump efficiency will be reported. The application of CFD solvers to forecast pump performance resulted in reduced prices for testing as well as pump development time. The numerical simulation concluded that placing cylindrical disks at the impeller inlet section improved the centrifugal pump performance under low flow rates.