Flow control techniques to improve the aerodynamic performance of Darrieus vertical axis wind turbines: A critical review

Vertical Axis Wind Turbines (VAWTs) have attracted considerable attention in recent years due to their potential for harvesting wind energy in urban areas and low wind speed environments. However, they suffer from inherent aerodynamic limitations such as low power coefficient and poor self-starting capabilities. To address these challenges, numerous flow control techniques have been proposed and investigated. The purpose of this review paper is to provide an overview of the various flow control techniques, including passive and active methods, that have been employed to improve the performance of Darrieus VAWTs. The concept of each flow control technique to suppress/delay separation and increase the lift-to-drag ratio is described. In addition, the effectiveness of each method is assessed based on its impact on key performance parameters. Moreover, the limitations of each technique are critically discussed and areas for further research and development are identified. Overall, this review provides valuable insights into different flow control techniques for improving Darrieus VAWTs and serves as a guide for future research in this area.