Parametric Analysis of Conventional Semicircular and Newly Developed Parabolic Rotors for Savonius-Style Wind Turbines: Three-Dimensional Numerical Simulations

Abstract Savonius-style wind turbines (SSWTs) are known for their simplicity and cost-effectiveness, making them ideal for small-scale power generation. While performance can be improved through augmentation techniques, these often add complexity. A promising approach is the use of innovative blade profiles, such as a parabolic design, which has shown improvements in two-dimensional (2D) numerical studies. However, three-dimensional (3D) analysis is crucial for more accurate insights. This study addresses this need by employing 3D numerical simulations to evaluate the performance of the newly developed parabolic rotor. The analysis is performed at a Reynolds number of 0.892 × 105 using a 3D shear stress transport (SST) k–ω turbulence model, and the results show that the novel rotor design increases the torque coefficient by 33% at a tip speed ratio (TSR) of 0.4, 20% at TSR 0.6, 11% at TSR 0.8, and 7% at both TSR 1.0 and TSR 1.2. The highest power coefficient (Cpmax) is observed at a TSR of 0.8, where the newly developed rotor achieves a Cpmax value of 0.217, compared to 0.196 for the traditional semicircular rotor. Additionally, the parametric study analyzes the influence of aspect ratio (AR) and wind speed effects on turbine performance, and the 3D numerical results show the semicircular rotor performs best at an aspect ratio of 1 and 8 m/s wind speed, while the parabolic rotor achieves optimal performance at an aspect ratio of 1.1 under the same conditions.