Power optimization of twin two-stage Savonius rotors based on Taguchi method: 3D study

The efficiency of twin Savonius vertical axis wind turbines (VAWTs) is studied by optimizing specific configuration parameters: distance between the turbines (S), their configuration angle (φ), and their combination of rotational directions (RD). The Taguchi method is utilized to systematically refine these parameters for optimal performance. The 3D unsteady and incompressible flow model of the system is solved numerically and validated. An orthogonal array (OA) L16 (4 3 ) is constructed for these factors and their four levels, presenting 16 arrangements. The best arrangement in OA increases the average power coefficient by 11.18% at a rated TSR of 0.8. The findings suggest that the power efficiency is primarily influenced by the configuration angle, with the rotation direction and turbine spacing following suit. The optimum arrangement increases the coefficient of power by 11.58% in comparison to the single turbine. Further analysis is conducted on the flow fields, pressure, and TKE distribution of the best and optimum arrangements.