A systematic study on the aerodynamic performance enhancement in H-type Darrieus vertical axis wind turbines using vortex cavity layouts and deflectors

The advantages of vertical axis wind turbines (VAWTs) have increasingly been recognized as effective turbomachines. Nonetheless, significant challenges remain regarding their efficiency and operational range. One promising approach to enhance their aerodynamic performance is the integration of vortex cavities, which can contribute to improved operational efficiency. This study utilizes computational fluid dynamics (CFD) to analyze the placement of vortex cavities systematically. The research investigates different configurations, such as suction side layout (SSL) and pressure side layout within single, double, triple, and quadruple arrangements to forecast their effect on H-type Darrieus VAWT aerodynamic performance. The findings show that the optimal configuration, with a concentration of 0.2 and 0.8 C in SSL, led to a 25% increase in power coefficient (Cp) at the tip speed ratio (TSR) of 3.3. Conversely, the suboptimal configuration, with a concentration of 0.2 and 0.4 C in SSL, resulted in a substantial 54% decrease in Cp at the same TSR due to issues with flow separation and lack of flow attachment after the vortex cavity. To optimize efficiency within the high-TSR range, a double, top, and bottom deflector configuration has been developed. Findings indicate that incorporating the double deflector has broadened the rotor's operational range from TSR 3.5 to 4.2 and concurrently elevated the rotor efficiency to 86%.