Aeroservoelasticity in Compressible Flow and Aeroelastic Scaling Considerations

Abstract

Active flutter suppression of a two dimensional wing section in subsonic flow is studied. The equations of motion of a typical section are presented in nondimensional form. A two degree of freedom system, with pitch and plunge dynamics, combined with a trailing-edge control surface is considered. Aerodynamic loads are expressed in time-domain using Roger’s approximation. Linear optimal control is used to design a full-state feedback regulator for flutter suppression. Constraints on actuator deflection and rate limit the flutter envelope expansion. Aeroservoelastic scaling is addressed and parameters required for maintaining similarity between a full-scale system and its model are identified. Results illustrate system behavior in compressible flow. Approximate relations comparing an actively controlled flap with a continuously deforming airfoil, using piezoelectric actuation, are obtained and used to compare the performance of these two systems.