Computational Modeling of Trailing Edge Fluidic Actuation for Rotor Blade Vibration Control

Prior investigations of aerodynamic flow control on rotor blades have focused primarily on manipulation of dynamic stall phenomena using leading-edge actuation. However, it has become apparent that these actuation approaches are ineffective when the base flow is fully (or nearly fully) attached at low to moderate angles of attack. In the present study two modes of fluidic actuation, steady blowing and pulsed jets, are employed to modify the cross-sectional aerodynamic loads of a two-dimensional airfoil at low to moderate angles of attack that are relevant for vibration control of helicopter rotors. Actuation is implemented near the trailing edge of the airfoil in order to affect aerodynamic loads by modifying the Kutta condition. Steady blowing and pulsed jet actuation are simulated using a computational fluid dynamics (CFD) framework. Time-resolved aerodynamic loads from the simulations are used to characterize the periodic shedding of trailing edge vorticity concentrations under steady blowing, as well as the unsteady transient response due to an impulsively started jet. The simulations are complemented by a series of wind tunnel experiments with steady blowing jets integrated on the suction and pressure surfaces of a VR-12 airfoil near the trailing edge. In order to reduce the computational cost of predicting unsteady lift, moment, and drag coefficients by CFD modeling, a surrogate-based reduced-order model is developed to accurately reproduce the CFD solutions based on a limited number of full-order simulations. This approach will be refined in future work and implemented in comprehensive aeroelastic simulations for rotor vibration reduction.