Effects of the influence of triangular dimple and aspect ratio on NACA 4412 airfoil on the overall performance of H-Darrieus wind rotor: An experimental investigation

Abstract

This study examines how adjusting aspect ratio (AR) and adding triangular dimples to the airfoil can enhance H-type Darrieus wind rotor (H-rotor) performance under low wind speeds (4, 6, and 8 m/s) using wind tunnel testing. Results show optimal performance at an AR of 1.0 for both standard and Triangular dimple airfoil H-rotors, with variations at different wind speeds for other aspect ratios. Triangular dimple-equipped H-rotors demonstrate improved self-starting capability and a wider operational range of tip speed ratio (TSR) compared to standard rotors, ensuring reliability across diverse wind conditions. Moreover, the triangular dimple rotor achieves a nearly 13.6% increase in maximum coefficient of power ( $C_{p,max}$ ) compared to the dimple-free H-rotor at 4 m/s wind speed. This study underscores the efficacy of adjusting AR and integrating triangular dimple blades to enhance H-rotor performance, particularly in low wind speeds.