Experimental Study on Influence of Aspect Ratio and Auxiliary Blade Profile on the Performance of H-Type Darrieus Wind Rotor

The performance of H-type Darrieus wind rotor (known as H-rotor) can be significantly influenced by altering its aspect ratio and incorporating an auxiliary airfoil. However, there is still a lack of comprehensive studies on the effects of these alterations. To address this gap, the present study aims to investigate the performance characteristics of H-rotors under low wind speed conditions (4–8 m/s) by using standard and auxiliary H-rotor configurations in a wind tunnel environment. A systematic analysis was conducted to examine the effect of altering the aspect ratio by changing the rotor diameter on both rotor configurations. The results of the study suggest that an aspect ratio of 1.0 provides the best performance for both standard and auxiliary H-rotors. The use of aspect ratios of 0.9 and 1.1 results in lower performance across all tested wind speeds. Moreover, the auxiliary H-rotor exhibits superior self-starting capability with a maximum static torque coefficient (Cts) of 0.119, which is 80.3% higher than the maximum Cts of the standard H-rotor (0.066). Additionally, the auxiliary H-rotor has a broader operating range of tip speed ratio (TSR) of 0.35–2.2 compared to the standard H-rotor TSR range of 0.4–1.9, suggesting that the auxiliary H-rotor can function dependably in diverse wind conditions. Furthermore, the auxiliary H-rotor achieves a nearly 5% increase in maximum power coefficient (Cp, max) compared to the standard H-rotor. The study emphasizes that the use of aspect ratio and auxiliary blades can effectively boost the efficiency of H-rotors in low wind speed conditions.