Active Flow-Control Concepts for Stall Alleviation and Post-Stall Lift Improvement of Vortex Dominated Fighter Configuration

It is proposed to experimentally explore two active separation-control concepts aimed at stall alleviation and maximum-lift improvement on generic, vortex-dominated fighter configurations. The concepts comprise a delta wing incorporating transversely-hinged apex flaps oscillating in the pitch plane, and a LEX-trapezoidal wing combination with root-hinged LEX's oscillating in the cross-plane. The common purpose of the active devices is to establish a hysteresis loop with average lift higher than the undisturbed wing lift at the same angle of attack. Even if the wing flow-field moves in and out of stall, it is anticipated that the time-averaged lift will be considerably improved. Low-speed wind tunnel tests will be conducted on two wing-body models in a wide range of angle of attack and with varying control surface frequency and amplitude parameters, measuring time-averaged six-component aerodynamic coefficients, wing surface pressures and near-wake velocity components, to determine the feasibility of the active devices and quantify their effectiveness. The potential of non-symmetrical activation of the devices for lateral control near stall will also be explored.