Aerodynamic synergy through cooperative vortex control in Savonius turbine clusters

Improving the performance of drag-type vertical axis wind turbines under low wind speed conditions has long been a key focus in wind energy research. However, most existing numerical studies adopt prescribed rotational speeds, which fail to accurately reflect the true dynamic response of wind turbines in natural wind environments. To address this limitation, a numerical simulation framework coupling wind-induced rotation with bidirectional fluid-structure interaction was developed to systematically investigate the aerodynamic behavior and cooperative vortex control-induced aerodynamic synergy of a three-turbine clustered Savonius system under various spatial arrangements. A combined approach integrating numerical simulation, Taguchi experimental design, and prototype testing was employed. The results indicate that radial distances and azimuthal angles have significant effects on both power output and startup performance. The simulation results show that the energy capture efficiency of the numerically optimized turbine cluster increased markedly from 0.0701 (isolated turbine) to 0.2858. Comparative analyses of velocity fields, pressure distributions, and vortex structures reveal that cooperative vortex control enables the cluster to suppress unfavorable vortex shedding, promote beneficial vortex attachment, and redistribute pressure fields, thereby sustaining higher torque throughout the rotation cycle. Wind tunnel experiments confirmed agreement with the simulation outcomes, providing theoretical guidance and engineering references for the deployment of clustered Savonius turbines in low-wind urban environments and distributed energy systems.