Renewable Energy Technology: Transient 3D CFD and Experimental Electrical Evaluation of a Cycloidal-Enhanced Rotor Versus a Savonius and Gorlov-Savonius Rotor with Blade Rotation Angle

This study presents a numerical and experimental analysis of vertical-axis Cycloidal rotors (RC) versus Savonius rotors (RS), with and without coupling to a Gorlov rotor (RG), designed to operate under low wind speed conditions of 2.5 m/s. Using transient Computational Fluid Dynamics (CFD), numerical mesh stability was evaluated as a function of rotor power, achieving convergence with 8,199,923 nodes and a stable angular momentum after 10 s. In the experimental phase, electrical characterization was conducted by coupling the rotors to a direct current generator, allowing for the determination of the optimal electrical load as a function of rotational speed (RPM). The results show that electrical power output and power coefficient (Cp) increased with rotational speed, reaching a maximum of 39.22 mW and Cp = 0.126 for the Cycloidal rotor (RCθR45), which exhibited the best overall performance. When coupling a Gorlov rotor with a torsion angle of 90° (RGθG90), maximum power of 52.45 mW and Cp = 0.168 were obtained for the hybrid configuration RC,θR0-RGθG90, confirming the aerodynamic and electrical performance improvement due to geometric coupling compared to a standalone Savonius rotor. The comparison between the numerical and experimental results showed consistent trends in Cp values, with slight deviations attributed to friction and alignment effects during physical testing. This study proposes an integrated methodology in renewable energy technologies that combines 3D transient CFD simulation with experimental characterization under variable electrical load conditions to determine the optimal operating power of novel Cycloidal rotors for low-wind-speed applications.