Jet flow control at the blade scale to manipulate lift

The turbulent atmospheric boundary layer in which wind turbines are implemented is strongly inhomogeneous and unsteady. This induces unsteady mechanical loads at different characteristic time scales from seconds to minutes which limits significantly their life time. Different control strategies have been proposed in the framework of the French ANR SmartEole project to alleviate the impact of these upstream fluctuations at the farm, wind turbine and blade scales (i.e. characteristic time scales from seconds to minutes). The present work, which is part of this ANR project, focuses on the flow control strategies at the blade scale, to manipulate lift and thus alleviate fatigue loads. The design of a NACA65(4)-421 airfoil profile has been modified to be able to implement jet control. Slotted jet and discrete jet configurations were implemented numerically and experimentally respectively. Results show the ability of both configurations to increase the lift by up to 30% using a significant redistribution of the mean shear. Efficiency seems to be more important using slotted jets, which however needs to be confirmed from 3D simulations.