A deployable vortex generator attached to a lifting surface includes a vane moveable relative to the lifting surface. The vane moves from a deployed position to a retracted position in response to a change in ambient conditions. In the deployed position, the vane acts on the air flow to create vortices. In the retracted position, the vane is closely aligned with the free stream velocity.

A system for reducing drag on an aircraft includes an ambient air inlet positioned in or near a wingtip fence and or winglet of the aircraft and an air pressurization device, such as an air compressor, coupled to the ambient air inlet. The air pressurization device has an inlet oriented toward the ambient air inlet. The air pressurization device has an outlet oriented toward an interior of the aircraft.

A method and system delay the laminar-to-turbulent transition of a supersonic or hypersonic boundary layer flow moving in a flow direction over a surface. For supersonic boundary layer flow, oblique first-mode instability waves present in the boundary layer and propagating at an oblique angle relative to the flow direction cause a laminar-to-turbulent transition in the boundary layer flow. These instability waves have a wavelength associated therewith in a direction perpendicular to the flow direction. Flow disruptors are used to generate modulations within the boundary layer flow wherein a wavelength of the modulations along the direction perpendicular to the flow direction is less than one-half of the wavelength of the instability waves. For hypersonic boundary layer flow, the flow disruptors generate modulations within the boundary layer flow wherein the wavelength of the modulations is less than streak spacing for optimal transient growth or, equivalently, in the range of one to two times the boundary layer thickness.

An airfoil is provided having reduced noise generation for use with an aircraft. The airfoil includes a body and a cover. The body has a leading edge spaced from a trailing edge and a side surface disposed between the leading edge and the trailing edge. The body defines an inlet proximate the leading edge and configured to receive air. The side surface defines an outlet in fluid communication with the inlet. The outlet is configured to exhaust air away from the side surface. The cover overlies the inlet and is movable between a first and a second cover position. The cover is configured to prevent movement of air through the inlet when the cover is in the first cover position and configured to permit movement of air through the inlet when the cover is in the second cover position.

A fluidic actuator for influencing a flow of a surrounding fluid along a flow surface has a blowing duct for connecting to a pressurized-fluid source, and has a surface blowing opening formed in the flow surface, and a suction duct for connecting to a surface suction opening formed in the flow surface, wherein the suction duct flows into the blowing duct at an entrainment opening.

A fluidic oscillator includes a structure having an input port and an output port. A chamber within the structure is configured to channel a fluid from the input port to the output port. A volume of the chamber is configured to change so as to change to change a frequency at which the fluid flows out of the output port.

Example active flow control systems and methods for aircraft are described herein. An example method includes supplying pressurized air to a plurality of nozzles. The nozzles arranged in an array across a control surface of an aircraft, and the nozzles are oriented to eject the pressurized air in a substantially streamwise direction. The method further includes activating the nozzles to eject the pressurized air in sequence to create a wave of air moving in a spanwise direction across the control surface.

An airflow diverter system for an aircraft may include an external aircraft surface upstream from an engine inlet and a passage having an upstream opening adjacent the engine inlet. The passage may be configured to channel boundary airflow from the external aircraft surface away from the engine inlet. The diverter system may include an occlusion device configured to selectively open and close the opening to the passage.

An assembly is provided for an aerial vehicle. This assembly includes an airframe and a fluid circuit. The airframe includes a body and an airfoil projecting out from the body. The airfoil includes a first surface and a first aperture in the first surface. The fluid circuit is configured to bleed gas from a gas turbine engine mounted to the airframe to provide control gas. The fluid circuit is configured to selectively direct the control gas to the first aperture.

A fluidic system is disclosed. The system comprises a plurality of fluidic oscillatory actuators, and at least one synchronization conduit connecting two or more of the actuators such as to effect synchronization between oscillations in the two or more connected actuators.