Numerical Study of a Vertical Axis Wind Turbine with an Inner Cylindrical Deflector

Climate change demands innovative renewable energy solutions, with wind energy emerging as a key resource. Vertical-axis wind turbines (VAWTs) are particularly suited for low-speed, turbulent wind environments due to their ability to capture wind from all directions. However, VAWTs face aerodynamic difficulties, especially at the downwind, where problems like negative torque and decreased efficiency are frequent. This study explores a novel solution for enhancing VAWT performance by incorporating an inner cylindrical deflector aimed at optimizing airflow around the blades. Using computational fluid dynamics (CFD) simulations, the study focuses on a three-bladed H-type VAWT with an airfoil profile of NACA0018 at a turbine diameter of 1 m. The simulations begin by evaluating a bare turbine arrangement, which shows negative torque beginning at an azimuth angle of about 165 degrees onwards. When a cylindrical deflector of different diameters is introduced, the torque coefficient and overall performance are greatly enhanced by a 0.3-meter diameter. The cylindrical deflector’s effectiveness is demonstrated by the 15% increase in power coefficient C pthat results from its inclusion. These results highlight how an inner cylindrical deflector could be a useful addition to VAWTs, resolving significant inefficiencies while preserving a positive angle of attack. This strategy offers a way forward for more effective VAWT designs in renewable energy systems in addition to increasing energy output. To enhance the efficiency of vertical-axis wind turbines (VAWTs) for both urban and rural applications, future research could investigate different configurations and empirically confirm these findings.OPEN ACCESS Received: 21/01/2025 Accepted: 10/03/2025 Published: 20/04/2025