Electromechanical and CFD-coupled analysis of deflector-guided savonius pico-hydro turbine with quarter-circular blade rotors
Global electricity demand continues to rise, increasing dependence on fossil fuels and accelerating greenhouse gas emissions that contribute to climate instability. Small-scale hydropower offers a clean alternative, particularly for distributed and space-constrained applications where conventional hydropower systems are difficult to implement. Among available concepts, the Savonius Pico-Hydro Turbine (SPHT) is attractive because of its simple structure, low production cost, and good self-starting capability. However, previous studies have mainly focused on mechanical performance, while the combined evaluation of mechanical response, electrical output, generator efficiency, and hydrodynamic flow behavior remains limited. The novelty of this study lies in the use of a quarter-circular blade profile instead of the commonly used semi-circular Savonius blade, combined with experimental electromechanical testing, CFD-based flow visualization, and deflector-angle variation. Two- and four-blade SPHT configurations were examined under realistic loading conditions, while CFD simulation was employed to clarify velocity distribution, pressure loading, momentum exchange, and deflector-guided flow patterns. The results showed that the four-blade rotor produced higher torque and a stronger electrical response than the two-blade rotor. CFD contour analysis supported these findings by showing stronger momentum exchange and more distributed pressure loading around the higher-solidity rotor. The deflector investigation further indicated that a 30° deflector angle provided the most effective flow redirection and pressure distribution among the evaluated cases. Overall, the proposed experimental and numerical framework provides a practical basis for optimizing quarter-circular SPHT design through blade configuration selection and deflector-angle tuning, supporting compact and reliable pico-scale clean energy generation for remote and low-infrastructure applications.