NASA's Langley Research Center has created a novel process that significantly improves the effectiveness of high-lift devices on aircraft wings by utilizing a hybrid concept of both sweeping jet (SWJ) actuators for active flow control (AFC) and adaptive vortex generators (AVGs) for passive flow control. High-lift technology reshapes aircraft wings for more lift during takeoff and landing. Conventional high-lift devices are complex and employ a significant number of parts. In addition, these complex mechanical high-lift systems (e.g., Fowler flap mechanisms) often protrude externally under the wings, resulting in increased cruise drag. Simple hinged flaps are preferable high-lift devices for low-drag cruise performance, but they are vulnerable to flow separation at high flap deflections for both trailing edge and leading edge applications. This innovation achieves higher flap deflections without flow separation while minimizing the pneumatic power requirement of AFC.
The combination of AVGs with SWJ actuators greatly improves flap efficiency. This unique hybrid approach can provide the necessary lift enhancement for a simple hinged flap high-lift system while keeping the pneumatic power requirement (mass flow and pressure) for the SWJ actuators within an aircraft's capability for system integration. A simple hinged flap high-lift design would have the benefits of lower weight without the Fowler flap mechanism, and less cruise drag without the external fairing for the Fowler flap mechanism.
For high-lift applications with a high flap deflection angle and a significant adverse pressure gradient, both SWJs and AVGs are activated for hybrid flow separation control (see figure, left). When the flap is deflected to a low deflection angle, only AVGs are activated to prevent possible flow separation initiated from the trailing edge. The cruise configuration has no flap deflection and there is no flow control activation (see figure, right).
This hybrid technology can potentially be used in aerospace applications on all hinged flap control surfaces of commercial and military aircraft (e.g., flaps, elevators, and rudders), and in marine applications on all hinged flap control surfaces of marine vessels (e.g., hydroplanes and rudders).