Influence of leading-edge tubercles on the aerodynamic performance of a horizontal-axis wind turbine: A numerical study

Leading-edge tubercles on the humpback whale pectoral fin are known to have aerodynamic benefits, particularly in the post-stall regime. In this research, a horizontal-axis wind turbine blade was modelled with tubercles distributed on its leading edge to mimic the humpback whale pectoral fin. A parametric study of the effect of tubercles on the reference NREL Phase VI wind turbine was conducted via computational fluid dynamics. Three parameters—amplitude, wavelength, and tubercle location along the blade span—were varied. The results showed that tubercles have negative effects on the turbine performance at wind speeds (V∞) ≤ 7 m/s. However, when tubercles are placed over 60% of the blade span, the backflow area can be eliminated at V∞ = 10 m/s. It is found that the vortices in the stable-flow zone over the suction surface can be reduced when tubercles of a relatively small amplitude-wavelength ratio are employed, thereby maintaining turbine performance. Compared with the reference blade, tubercles provided benefits at higher wind speeds. The generated vortices due to the presence of tubercles, leading to both blockage effects and stall delay. The results revealed that the pressure on the suction surface of the tubercled blade decreases, thereby increasing lift and enhancing the turbine performance. •Three parameters are considered in defining a sinusoidal (tubercle) leading-edge.•The new-type blade shape shows beneficial aspects under off-design conditions.•The blade with tubercles is proved to be unfavorable under on-design conditions.•The peaks of leading-edge tubercles are responsible for delaying separated flows.•The spanwise-flow of blades beyond stall is suppressed at high wind speeds.