Bio-inspired design of leading-edge tubercles on wind turbine blades

As global CO2 emissions continue to rise, the demand for renewable and sustainable energy resources rises in conjunction. One such method for producing renewable energy is wind turbines, which convert kinetic energy into useful electrical energy. As the world's biggest offshore wind energy market, the UK has been investing in green energy to mitigate the impacts of climate change. As part of the 2050 vision for net-zero emissions, the UK aims to boost the total installed offshore capacity by four-fold to 40GW by 2030. The energy conversion efficiency is primarily determined by the aerodynamic performance of the wind turbine blades. By optimising the blade design, the maximum attainable energy can be produced. Biomimetics may aid in this optimisation by emulating the Humpback whales flipper morphology for aerodynamic applications. It has been hypothesised that leading-edge tubercles can increase the post-stall lift and reduce the induced drag. This paper analyses the aerodynamic characteristics of a NACA-0021 aerofoil with leading-edge tubercles. The analysis is conducted in the Northumbria University low-speed wind tunnel, aiming to compare the tubercle aerofoil's pressure distribution, lift, and stall angle against the smooth aerofoil. The results indicate that leading-edge tubercle blades can enhance post-stall lift by 115%, thus indicating a reduction in induced drag in the post-stall region.