A comprehensive review of the application of bio-inspired tubercles on the horizontal axis wind turbine blade

The airfoil shape in the turbine blades is responsible for lift generation in horizontal axis wind turbine (HAWT). However, the main problem is the occurrence of stalls on the blade after a certain angle of attack. It is noticed in the literature that vortex generator, tubercle, micro cylinder, spherical ball, etc., can enhance the momentum transfer in the wind turbine blade and can help in increasing lift production. Simultaneously, these modifications help in delaying the stall occurrence on the blade. In the present study, an attempt is made to review the different modifications done on the leading edge of the HAWT blade using tubercles and their effects on aerodynamic performances. From the study, the following significant findings are summarized with respect to the performances of HAWT with leading-edge tubercles: (i) blades with tubercles on the leading edge will have superior performance in the post-stall regime, (ii) tubercles with a smaller amplitude and lower wavelength will produce higher lift and lower drag in the low wind speed condition, whereas, at higher wind speed, tubercles with higher amplitude and larger wavelength perform better, and (iii) tubercle blade will have a stable and smooth performance in varying wind speed conditions, producing higher torque and power at low wind speed. Finally, some crucial scopes for future research for further developing the HAWT with tubercle blades are delineated.