Dynamic Flow Response Due to Motion of Partial-Span Gurney-Type Flaps

Abstract

Uninhabited air vehicles are commonly designed with high-aspect-ratio wings, which can be susceptible to significant aeroelastic vibrations. These oscillations can result in a loss of control or structural failure, and new techniques are necessary to alleviate them. A multidisciplinary effort at Stanford developed a distributed flow control method that used small trailing-edge actuators, known as micro-trailing-edge effectors (MiTEs) to alter the aerodynamic loads at specific spanwise locations along an airplane wing. The actuators were based on a Gurney flap, which is a trailing-edge flap of small size and large deflection, allowing an increase in lift with a small drag penalty. The transient response caused by relatively rapid MiTE actuation was studied using particle image velocimetry in the near wake. The transient response was quasi-steady for dimensionless actuation times (tU∞/c) near unity. A shorter dimensionless actuation time of 0.2 produced a transient response with significant overshoot of the downwash velocity in the near wake. This indicated a nonmonotonic response of the aerodynamic loads for rapid actuation.