Experimental Study on the Influence of Aspect Ratio and Triangular Dimple on Blades of H-Darrieus Wind Rotor on Self-starting Capability

This study investigates the impact of altering the aspect ratio and introducing a triangular-shaped dimple on the airfoil of H-Darrieus wind rotors, commonly known as H-Darrieus rotors, with a focus on their self-starting characteristics under low wind speed of 4 m/s. In a wind tunnel environment, standard H-Darrieus rotor configurations and rotors with triangular-shaped dimples on the blade profiles were systematically analyzed, specifically examining the effects of varying aspect ratios by modifying the diameter of the rotor for two configurations. The findings reveal that an aspect ratio (AR) of 1.0 yields optimal characteristics for both the standard H-Darrieus rotor and the rotor with a dimple on the blade profile, while aspect ratios of 0.8, 0.9, 1.1, and 1.2 result in lower performance at a wind speed of 4 m/s. Furthermore, the turbine with a dimple on the blade profile demonstrates superior self-starting ability, achieving a higher static torque coefficient ( \({C}_{ts}\) ) of 0.084. This represents a significant improvement of 18.3% compared to the maximum \({C}_{ts}\) of the standard rotor, which stands at 0.071. The study underscores the efficacy of utilizing aspect-ratio adjustments and incorporating triangular dimples on blades as effective strategies to enhance the self-starting characteristics of H-Darrieus rotors, particularly in low wind speed conditions.