The aerodynamics of a Savonius blade

Faced with the energy crisis and global warming, renewable energies are emerging as a key response, particularly wind power. Among these various technologies, vertical axis wind turbines (VAWTs) present a promising energy source in rural areas. The Savonius rotor, a drag-driven device, one of the famous vertical axis wind turbine designs, offers many advantages such as easy installation and fast automatic start-up. However, its efficiency is limited by negative torque on the return blade. Research aims to improve this rotor by optimizing many factors as the overlap ratio and blade shape, while integrating technologies such as end plates and deflectors to minimise the negative torque and increase energy production. The power factor of a conventional Savonius rotor extends from 0.12 to 0.18, but improvements could increase it to 0.52. This article provides an in-depth analysis of performance and power enhancement technologies for Savonius rotors, suggesting future prospects. In addition to examining proven solutions, the article highlights new avenues of research that could strengthen the role of this rotor in the future energy mix.