Simulation of active flow control actuator using CFD with application to rotor blade vibration reduction

Abstract

A computational fluid dynamics (CFD) model is developed to determine the unsteady aerodynamic effects of active flow control implemented by combustion-powered actuation (COMPACT) on a two-dimensional airfoil. Previous work with COMPACT actuators employed pulsed-jet actuation at moderate to high angles of attack to control flow separation and dynamic stall. However, the focus of the present study is to implement actuation in the moderate to low angle of attack range suitable for helicopter rotor vibration control. At low angles of attack, the effect of actuation on the sectional aerodynamic forces of the airfoil diminishes. Therefore, modifications to the COMPACT actuator con1guration are considered to enhance the actuation authority for the relevant operating range. Modifications include placing a ramp on the airfoil upstream of the actuator and relocating the actuator near the airfoil trailing edge. These are considered using both CFD simulations and wind tunnel experiments, which are compared to validate the CFD model. Finally, a surrogate-based reduced-order modeling technique is described to address the high computational cost of the CFD simulations. The reduced-order model is used to accurately reproduce full-order CFD results for the unsteady changes in lift, moment, and drag due pulsed actuation on a static airfoil. Furthermore, the results show that the reduced-order model represents a feasible method for representing the unsteady aerodynamic effects of COMPACT actuation. This will be refined in future work and implemented in a comprehensive aeroelastic code for helicopter rotor vibration reduction.