Performance Comparison of Reverse-Engineered and Newly Designed Impellers in a Centrifugal Pump Operating in Pump and Turbine Modes

This study compares the hydraulic performance of two centrifugal-pump impellers operating in pump and pump-as-turbine (PAT) modes: a reverse-engineered impeller obtained from a commercial pump by 3D scanning and an impeller developed through a preliminary analytical sizing procedure. Both configurations were evaluated under the same computational framework using OpenFOAM, the Multiple Reference Frame approach, and the k- omega SST turbulence model. Hydraulic performance was assessed through efficiency, pressure, velocity, and turbulent-dissipation fields, complemented by velocity-triangle and parametric sensitivity analyses. The reverse-engineered impeller achieved efficiencies of 90.50% in pump mode and 67% in PAT mode, compared with 79.17% and 50%, respectively, for the analytically designed impeller. Internal-flow analysis indicated that the reverse-engineered geometry produced more uniform velocity and pressure distributions and less extensive turbulent-dissipation regions. Velocity-triangle analysis indicated that its inlet blade angle increases the incidence mismatch in pump mode but reduces residual tangential velocity in PAT operation, favoring angular-momentum transfer. Sensitivity analysis indicated that the dominant geometric parameters depend on the operating direction. The analytical procedure is therefore interpreted as a preliminary sizing approach rather than a validated dual-mode optimization method. Overall, the results indicate that reversible impeller design should consider both operating directions and subsequent CFD-based refinement.