Effect of Single and Multiple Protuberances on the Aerodynamic Performance of a Wind Turbine Blade

Wind energy currently contributes to nearly 5% of our global electricity production and plays a vital role amongst other renewable energy resources. This work aims to numerically investigate the aerodynamic performance of a NACA 634-021 blade with single and multiple spanwise leading-edge protuberances. Different configurations of protuberances viz. continuous and equally spaced intermittent profiles are evaluated for aerodynamic performance. The numerical simulations showed that stall onset is preponed by the protuberance, however, the performance is improved in the post-stall regime. At 27° angle of attack, the continuous protuberances led to the performance improvement of 44%, whereas intermittent protuberances enhanced the blade performance by 37%. Negligible improvement was observed with a single protuberance. Subsequent studies demonstrated that the formation of counter-rotating vortex pair and their interaction with the retarding boundary layer imparts much-needed momentum and plays a significant role in controlling the stall inception. At higher post-stall angle of attack, the continuous protuberances supersede all other cases.