Optimized Foil-Based Impeller Design for Enhanced Power Recovery in Pump-as-Turbine Applications

A pump operating as a turbine (PAT) is a type of hydraulic machine capable of functioning both as a pump and as a turbine by reversing the flow direction. The pump-as-turbine (PAT) approach presents an effective method of hydropower generation, particularly suitable for addressing the increasing global energy demands in rural and remote areas. In addition to its adaptability, PAT-based micro-hydropower systems typically incur lower operating costs than conventional hydrodynamic turbines, despite requiring higher initial investment. Recent research has focused on integrating PATs into pipe distribution systems to harness untapped hydraulic energy. This study presents the development and performance evaluation of a novel pump operating as a turbine (PAT) impeller, designed to enhance hydropower recovery in water distribution systems. A three-dimensional (3D) impeller model was created using Catia software, integrating airfoil (hydrofoil) geometries into the blade profile to improve the efficiency of power extraction during turbine operation. Unlike conventional designs, the new impeller configuration generates additional force components aligned with the rotor’s direction of rotation, thereby increasing the moment about the axis and enhancing angular velocity. Computational fluid dynamics (CFD) simulations performed in ANSYS Fluent confirmed that the redesigned PAT significantly improves both performance and efficiency, demonstrating superior power recovery compared to the original design. The results highlight the potential of integrating PAT systems with optimized blade geometries into water distribution networks, offering a viable solution for energy recovery and head reduction during periods of low demand.