A Study of Morphing Trailing Edge Flaps Applied on Offshore Wind Turbine
Wind turbines are operating in a highly unsteady flow environment which causes dynamic load fluctuations relevant to the overall wind turbine design. Fatigue loads play an important role in the aeroelastic rotor development and contribute significantly to the turbine costs as blade loads cascade down through the entire turbine system. A reduction of fatigue loads can thus have a positive influence on the rotor weight, costs and system reliability or allow a further increase of the rotor diameter. Active trailing edge flaps (ATEFs) represent a very promising approach for the reduction of fatigue and also ultimate loads. By adapting the deflection angle it is possible to adjust to the current inflow situation and reduce load fluctuations. The present study investigates the influence of three-dimensional aerodynamic effects on a wind turbine rotor blade with trailing edge flap by means of CFD. Different flap extensions in chord and radial direction can be analyzed on rotor blade. The study shows that to 2D airfoil simulations at mid flap position shows that vortices which develop at the flap edges have a significant influence on the aerodynamic characteristics. They reduce the lift increase or decrease caused by the flap deployment and thus the flap effectiveness. As compared to 2D, 3D effect shows reduction in lift variation.