Trailing edge flow control for the mitigation of dynamic stall effects

The use of an actively controlled flap for the reduction of dynamic stall induced vibration is demonstrated via CFD. Two separate flap actuations are considered. In the first instance, a moderate advance ratio dynamic stall case is examined by using a 3D Aeroelastic code, GAST, which couples a vortex particle method, and dynamics equations for a beam model. This case employs a downward flap deflection to reduce the portion of the rotor disk area over which dynamic stall is encountered. The second approach targets dynamic stall occurring in high advance ratio forward flight configurations. 2D RANS simulations were performed. In this case, an upward flap deflection is employed in order to control the strength of the trailing edge vortex. In both cases the flap served to reduce the amplitudes of vertical blade reaction forces, blade torsional moment and negative aerodynamic damping, indicating a net reduction in the vibration experienced by the rotors