Active Flow Control Virtual Maneuvering System Applied to Conventional Airfoil

摘要

This paper describes unconventional techniques to manipulate the pressures, forces, and moments acting on an airfoil without movable control surfaces. The method relies on active flow control (AFC), a versatile tool for modifying flowfields to create innovative flow effectors. By the generation of unsteady vortices emanating from suction and oscillatory blowing (SaOB) actuators, attached or incipiently separated flows are forced to be separate or become more attached. In this way, pressures, forces, and moments acting on an airfoil can be altered in a desired and controlled manner. Wind-tunnel tests performed on the Israel Aerospace Industries AR2 low-Reynolds-number airfoil included baseline and AFC configurations. The airfoil was instrumented with two independent SaOB actuator arrays. If eventually the concept can be transferrable to finite wings it would create an alternative maneuvering system, with no moving parts. It was found that the current AFC system is capable of increasing the lift (as a virtual flap system) or increasing the drag (as a virtual spoiler) while only weakly altering the other parameter, over a wide range of incidence angles from zero lift to stall. The system has an effect that is deemed minor on the airfoil pitching moment, again to be evaluated on a specific three-dimensional configuration. The effects of the mass and momentum transfer on the estimated forces and moments are discussed as well.