Introducing the toroidal blade concept to small-scale horizontal axis wind turbine: A CFD study

This study evaluates the toroidal blade concept in horizontal-axis wind turbine design compared to conventional shapes. Both designs utilize the NACA 4412 airfoil, with the toroidal rotor featuring elliptical geometry. Three-dimensional transient CFD simulations using URANS equations and advanced turbulence models were conducted in ANSYS Fluent. Multiple Reference Frame and sliding mesh techniques captured dynamic vortex phenomena and turbine behavior. Parametric analysis identified 0.50 as the best looping ratio. The study emphasizes flow separation, tip vortices, and power efficiencies at a low Reynolds number regime (7 m/s). Validated against theoretical and experimental data, results suggest that the toroidal blade enhances the power coefficient, mitigates tip-vortex strength, and stabilizes unsteady flows. Specifically, the power coefficient increased by 22.5% over the conventional turbine at the optimum tip-speed ratio. These findings advance toroidal blade fluid dynamics and offer design guidelines for efficient wind energy harvesting.