Performance Improvement of Hybrid Vertical Axis Wind Turbines Equipped With J-Shaped Blades

Vertical axis wind turbines (VAWTs) are emerging as a promising solution for urban wind energy harvesting, owing to their omnidirectional capability. Hybrid VAWTs, which combine Savonius and Darrieus turbines, have shown improved power performance, yet their commercialization remains limited by challenges in self-starting ability and operational range. The present study introduces a novel hybrid configuration using J-shaped Darrieus blades with a NACA 0021 airfoil profile, to improve self-starting ability, power production, and operational range. The rotor has a diameter of 1 m, and numerical simulations using the computational fluid dynamics (CFD) method with the SST k-ω turbulence model were conducted to evaluate aerodynamic performance. Various opening ratios of 30%, 50%, 70%, and 90% were analyzed, revealing that the 30% opening ratio produces the highest power output across a broad range of tip speed ratios (TSRs). Specifically, using J-shaped Darrieus blades with a 30% opening ratio enhances power output by 50% at TSR = 1.5% and 14.4% at TSR = 2.5, compared to the baseline model. These findings highlight the potential of J-shaped blades to optimize hybrid VAWT performance for practical applications, offering enhanced efficiency.