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.

Example active flow control systems and methods for aircraft are described herein. An example active flow control system includes a plurality of nozzles arranged in an array across a surface of an aircraft. The nozzles are oriented to eject air across the surface to reduce airflow separation. The active flow control system also includes an air source coupled to the nozzles and a controller to activate the nozzles to eject air from the air source in sequence from outboard to inboard and then from inboard to outboard to create a wave of air moving from outboard to inboard and then from inboard to outboard across the surface.

An air intake system comprising an air duct suitable for providing airflow to the inside of an aircraft, preferably to an auxiliary power unit; an inlet arranged at one end of the air duct; a skin surrounding the inlet; a plurality of slots arranged on the skin; a driving arrangement, a flap door connected to the driving arrangement, and a plurality of fins connected to the driving means. The driving arrangement is configured for moving the flap door between at least two positions, the positions being a closed position wherein the flap door closes the inlet, and an opened position wherein the flap door is driven away from the closed position. The driving arrangement is also configured for moving the plurality of fins such that the plurality of fins protrudes through the slots.

A control system operable includes a modified primary control parameter for an aircraft, the control system includes: a primary control parameter leg configured to output a demand in an aircraft primary control parameter; a primary control parameter compensation leg configured to receive a change in absolute levels and/or spatial distributions of swirl angle and/or fan pressure at a primary control parameter relative to a reference and convert the change into the primary control parameter; a processor adapted to receive the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; compare the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; and generate a modified primary control parameter for the aircraft.

A method of estimating a parameter of a fluid flowing in a passage includes: having a plurality of instruments operable to measure one or more fluid properties flowing in the passage, the plurality of instruments being disposed in the passage and arranged within a common measurement plane; assigning a stream tube to each instrument, each stream tube represents a region of space in the common measurement plane within the passage and each stream tube surrounds one of the plurality of instruments, the stream tubes together correspond to the cross-sectional shape and area of the passage in the common measurement plane; measuring the one or more fluid properties using the instruments to obtain one or more measured values for each stream tube; using the measured value(s) for each stream tube to calculate a derived value for each stream tube; and summing the derived values across all of the stream tubes.

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.

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.

An assembly is provided that includes a regulator manifold and a regulator element. The regulator manifold includes an inlet passage, a first outlet passage and a second outlet passage. The inlet passage is configured to receive bleed gas from a core flowpath. The regulator element is within the regulator manifold and configured to pivot to a first position, a second position and an intermediate position between the first position and the second position. The regulator element is configured to fluidly couple the inlet passage with the first outlet passage in the first position. The regulator element is configured to fluidly couple the inlet passage with the second outlet passage in the second position. The regulator element is configured to fluidly decouple the inlet passage from the first outlet passage and the second outlet passage in the intermediate position.

A propulsion system coupled to a vehicle. The system includes a convex surface, a diffusing structure coupled to the convex surface, and at least one conduit coupled to the convex surface. The conduit is configured to introduce to the convex surface a primary fluid produced by the vehicle. The system further includes an intake structure coupled to the convex surface and configured to introduce to the diffusing structure a secondary fluid accessible to the vehicle. The diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid and secondary fluid.

An active flow control drag-induced damping reduction apparatus. The apparatus includes a variable frequency signal power supply; a jet generator defining an internal cavity and having pump member, and coupled to the variable frequency signal power supply to receive a control signal; a feedback sensor coupled to the pump member to generate a feedback signal measuring the reciprocating motion of the pump member; a detection circuit that receives the feedback signal and measures a difference compared to the variable frequency generator; and an adjustment circuit that receives the measured difference and tunes the variable frequency signal of the variable frequency signal power supply to maintain the jet generator at an optimum flow.