Study of the influence of oscillating trailing edge flaps on the AVATAR rotor using CFD simulations

In the present paper the effect of an oscillating trailing edge flap on the wind turbine blade loading and performance is investigated. Two CFD Unsteady Reynolds Averaged Navier-Stokes (URANS) solvers along with a simpler engineering Blade Element Momentum (BEM) model are used to simulate sinusoidal trailing edge flaps with a length of 10% chord and 10 degrees maximum deflection, centered at 75% span and extending at 15% of the blade radius. The predictions reveal significant 3D effects on the hysteresis, as well as the location and magnitude of the maximum amplitude of loading. The increase of flapping frequency from 1P to 3P results in lower amplitude and larger hysteresis. A stronger influence of the flap is observed at the negative flap angles. The effect of increasing the flap length on the power and thrust of the turbine rotor is also investigated.