Abstract: A synthetic jet muffler includes an exit end, a propagation path for conducting a first sound wave emitted by a synthetic jet generator to the exit end, and a shroud for conducting a second sound wave emitted from the synthetic jet generator in a direction opposite to the first sound wave to the exit end, wherein the shroud is disposed so that the first and second sound waves travel different distances to effect noise cancellation at the exit end.

Abstract: An aircraft with aerofoils including a main wing and a control flap that includes an adjustment flap. The aircraft includes an actuator for the control flap, as well as a sensor device for acquiring the position of the control flap, an arrangement of flow-influencing devices for influencing the fluid that flows over a segment of the main wing, and flow-state sensor devices for measuring the flow state. The aircraft includes a flight control device connected to the sensor device for acquiring the position of the control flap and to the flow-state sensor devices, and connected to the actuator and flow-influencing devices for transmitting actuating commands, and a flight-state sensor device connected to the flight control device for transmitting flight states. The flight control device includes a function that selects the flow-influencing devices that are operated for optimizing local lift coefficients on the aerofoil, depending on the flight state.

Abstract: A nacelle assembly for a turbine engine has a cowl for a turbine engine. The cowl has a first surface spaced from a second surface. The second surface defines defining a bypass flow passage. A flow volume is spaced between the first surface and the second surface. A plurality of holes are disposed on the cowl. Each of the plurality of holes are configured to alter local air pressure about one of the first surface and the second surface of the cowl. The plurality of holes are in communication with the flow volume.

Abstract: A rotorcraft may include an airframe and a rotor connected to the airframe. The rotor may include a plurality of blades defining ducts along the length thereof and vents in fluid communication with the ducts. Flow from through the vents may be controlled by valves with piezoelectric actuators. The valves may be adjusted to achieve a lift profile suited for an operational mode such as vertical, autorotative, or unloaded flight. The lift profile may vary along the length of the blade and may vary cyclically with rotation of the blade. The lift profile may be chosen to approximate a figure of merit for the rotor suitable for a given operational mode.

Abstract: A tail section for an aerospace vehicle is provided. The tail section comprises a rudder which is movable about an axis to generate a yawing moment on the aerospace vehicle. The tail section further comprises a thruster having, in flow series, an air intake, an electrically powered device for accelerating the air received through the intake, and an air outlet which directs the accelerated air to increase the yawing moment generated by the rudder.

Abstract: A system for controlling unwanted flow separation. One or more microjets are placed to feed auxiliary fluid into a region of suspected flow separation on a surface. If the separation is intermittent, sensors can be employed to detect its onset. Once separation is developing, the microjets are activated to inject a stream of high-velocity gas in a direction that is transverse to the prevailing flow. This injected stream forms counter-rotating vortices in the prevailing flow and thereby transfers momentum from the prevailing flow into the boundary layer proximate the surface.

Abstract: An apparatus for supplying a gas flow over an aerodynamic structure is provided. The apparatus includes a fluid source for supplying the gas flow and a flow control actuator configured to receive the gas flow from the fluid source. The flow control actuator is also configured to selectively direct the gas flow over the aerodynamic structure when the flow control actuator is in at least one predetermined operating position and to restrict the gas flow over the aerodynamic structure when the flow control actuator is in another of the predetermined operating positions.

Abstract: A high efficiency, adaptive control, compound ducted wind turbine capable of providing higher efficiency in energy extraction from a fluid. Performance of efficiency expressed as coefficient of performance (Cp) in accordance with the Lanchester-Betz-Joukowski limits is sustainable and significantly higher than an un-ducted, mono-propeller wind turbine of comparable diameter. Also an active circulation control wing technology is disclosed for increasing efficiency and performance and which is applicable to both wind and water turbines.

Abstract: An air pump positioned within a hollow space in an aerodynamic structure for controlling the flow over an aerodynamic surface thereof, includes a movable member linearly displaced by a very low friction piston mechanism and a compression chamber open to the exterior of the aerodynamic surface through an orifice. Reciprocal displacement of the very low friction movable member changes the volume of the compression chamber to alternately expel fluid (e.g., air) from and pull fluid into the compression chamber through the orifice. The movable member includes a piston oscillating within a piston housing each having an ultra-low friction coating for improved thermal performance and reduced maintenance. Fluid intake to the compression chamber may be increased through the use of a one-way valve located either in the aerodynamic surface, or in the piston. Multiple flapper valves may surround the orifice in the aerodynamic surface for increased fluid control.

Abstract: An ejector nozzle tube, having along its length an essentially constant, essentially oval hollow cross-section, with a leading edge nozzle, having a rounded exterior cross-section, being arranged at a flow leading-edge area of the ejector nozzle tube. The leading edge nozzle includes a plurality of grooves issuing to the top and bottom sides of the ejector nozzle tube and connecting to an interior of the ejector nozzle tube formed by the hollow profile. An aircraft engine has an optimized oil heat exchanger with at least one oil cooler disposed in a trailing-edge area of an aerofoil-type structure, with at least one flow entrance area being provided to supply ambient air to the oil cooler disposed in a flow duct. The ejector nozzle tube can be arranged downstream of the oil cooler in the flow duct.

Abstract: Systems and methods for reducing the trailing vortices and lowering the noise produced by the side edges of aircraft flight control surfaces, tips of wings and winglets, and tips of rotor blades. A noise-reducing, wake-alleviating device is disclosed which incorporates an actuator and one or more air-ejecting slot-shaped openings coupled to that actuator and located on the upper and/or lower surfaces and/or the side edges of an aircraft flight control surface or the tip of a wing, winglet or blade. The actuation mechanism produces sets of small and fast-moving air jets that traverse the openings in the general streamwise direction. The actuation destabilizes the flap vortex structure, resulting in reduced intensity of trailing vortices and lower airplane noise.

Abstract: An air intake for a supersonic air-breathing flight vehicle introduces or injects fluid in order to create predetermined regions of separated flow and an attendant fluid shear layer. This shear layer forms an aerodynamic boundary for the capture flow with a profile determined and optimised by appropriate injection of fluid. The aerodynamic boundary so generated replaces mechanically moveable solid surfaces used to vary the geometry of prior-art intakes. Use of an introduced or injected fluid can provide an advantage of a variable geometry, but with reduced weight and reduced mechanical complexity. In some embodiments, the injection of fluid has the effect of re-energizing any ingested boundary layer, thus obviating the conventional requirement for a bleed system to provide boundary layer control.

Abstract: An aircraft turbojet nacelle comprising blowing means intended to inject a tangential airflow (Ft) into the internal volume (V) of the nacelle, said blowing means being provided in a wall of the air intake of the nacelle in the supersonic area of said air intake. The invention also concerns a method for controlling separation in an aircraft nacelle, wherein a tangential airflow is injected (Ft) into the internal volume (V) of the nacelle in the locally supersonic area of the air intake so as to pull the main airflow (F) into the extension of the inner wall of the nacelle.

Abstract: Systems and methods for reducing the trailing vortices and lowering the noise produced by the side edges of aircraft flight control surfaces, tips of wings and winglets, and tips of rotor blades. A noise-reducing, wake-alleviating device is disclosed which incorporates an actuator and one or more air-ejecting slot-shaped openings coupled to that actuator and located on the upper and/or lower surfaces and/or the side edges of an aircraft flight control surface or the tip of a wing, winglet or blade. The actuation mechanism produces sets of small and fast-moving air jets that traverse the openings in the general streamwise direction. The actuation destabilizes the flap vortex structure, resulting in reduced intensity of trailing vortices and lower airplane noise.

Abstract: A nacelle assembly for a turbine engine has a cowl for a turbine engine. The cowl has a first surface spaced from a second surface. The second surface defines defining a bypass flow passage. A flow volume is spaced between the first surface and the second surface. A plurality of holes are disposed on the cowl. Each of the plurality of holes are configured to alter local air pressure about one of the first surface and the second surface of the cowl. The plurality of holes are in communication with the flow volume.

Abstract: An unmanned air system and method with blown flaps are presented. Air is guided to a fuel cell carried by the unmanned air system. The fuel cell is ventilated by the guided air such that the air is heated by the fuel cell to provide heated air. The heated air is routed from the fuel cell to one or more high lift devices on a lift device of the unmanned air system to provide routed air. The routed air is blown across the high lift devices.

Abstract: An aerofoil defining geometric upper and lower surfaces which together form a leading edge region and a trailing edge region, and comprising a blowing device having a slot in the lower geometric surface in the leading edge region for injecting fluid into the airflow over the aerofoil, wherein the slot is located forward of the leading edge stagnation point at the critical angle of incidence of the aerofoil, and wherein the blowing device is adapted to inject the fluid forwardly of the slot and substantially parallel to the lower surface. Also, a method of improving the performance of the aerofoil by injecting fluid into the airflow over the aerofoil from the slot. The upper surface of the aerofoil can be kept clean, giving the potential for laminar flow during cruise without significantly compromising the high lift performance of a blown leading edge at high incidence.

Abstract: Apparatus and methods provide for a swept-wing powered-lift aircraft. Aspects of the disclosure provide a powered-lift aircraft that utilizes the engine exhaust flow over upper surface blown flaps to increase lift during various flight operations. The powered-lift aircraft has wings with inboard portions and outboard portions. The adjacent inboard and outboard portions share a swept leading edge. The leading edge is swept to a degree that shifts the outboard portion rearward to a position in which the aircraft center of lift has little to no variance upon the activation or deactivation of a powered-lift system.

Abstract: An STOL and/or VTOL aircraft comprises (1) a fuselage having a front end, a rear end and two lateral sides, the fuselage defining a substantially horizontal central longitudinal axis of the aircraft; (2) an aircraft tail arranged at the rear end of the fuselage and including a rudder and an elevator on each side of the fuselage with movable surfaces for controlling the aircraft; and (3) a wing on each side of the fuselage having a front edge, a trailing edge and an upper surface extending from the front edge to the trailing edge. A device for controlling the airflow over the upper surfaces of the wings comprises openings in these upper surfaces for the egress of air from interior spaces within the wings and air pump apparatus for pressurizing such interior spaces.

Abstract: Concepts and technologies described herein provide for the creation of an actuating fluid flow utilizing a multi-stage actuator. According to one aspect of the disclosure provided herein, a fluid actuation system includes at least two stages, each stage having a plenum and one or two diaphragms acting on the plenum to create an actuating fluid flow. The diaphragms of each stage may be substantially aligned along an axis. The actuating flow is aggregated between stages and expelled into a fluid flow to be controlled. According to various aspects, the diaphragms may include piezoelectric discs.

Abstract: An aircraft leading edge is extended by an aerodynamic surface providing an aerodynamic flow and where air discharges are arranged preventing separation of the aerodynamic flow. The air discharges are arranged in at least two rows essentially parallel to the leading edge and in an offset manner for at least two consecutive rows. At least one block is inserted between two walls that form the aerodynamic surface. The block includes, on the one hand, an outside surface extending the aerodynamic surface, a first inclined surface contacting the first wall forming the aerodynamic surface, and a second inclined surface contacting the second wall that forms the aerodynamic surface, and, on the other hand, projecting and/or hollow shapes that are made at the inclined surfaces and that are arranged in an alternating fashion from one surface to the next, allowing air to pass on both sides of the aerodynamic surface.

Abstract: An aerodynamic body with an outside with a top and bottom in relation to the direction of airflow, with lateral end parts that form the lateral ends of the aerodynamic body when viewed across the direction of airflow, where in the interior of the aerodynamic body a duct with an airflow drive with a drive motor and a compressor means that is driven by the aforesaid and that is arranged in the duct is arranged, with at least one inlet at the bottom and/or at at least one of the lateral end parts of the aerodynamic body and with at least one outlet at the top of the aerodynamic body for influencing the airflow at the aerodynamic body is arranged, where in the duct a sleeve is arranged which is rotatable by means of a drive motor, which sleeve includes at least one recess which at a particular rotational position of the sleeve can be made to at least in part coincide with the outlet at the top of the aerodynamic body so that the air that has been compressed by the compressor flows through the recess in the sleeve

Abstract: Apparatus and methods provide for a swept-wing powered-lift aircraft. Aspects of the disclosure provide a powered-lift aircraft that utilizes the engine exhaust flow over upper surface blown flaps to increase lift during various flight operations. The powered-lift aircraft has wings with inboard portions and outboard portions. The adjacent inboard and outboard portions share a swept leading edge. The leading edge is swept to a degree that shifts the outboard portion rearward to a position in which the aircraft center of lift has little to no variance upon the activation or deactivation of a powered-lift system.

Abstract: A jet of air is impelled on to the upper surface of a flap in order to increase its lift. Part of the air in this air jet is drawn, through air intakes, from the air stream flowing over an upper surface of the fixed part of the wing, located upstream of the flap. The air jet drawn in by suction by the air intakes is reinforced by a jet of compressed air blown through a passage which opens immediately downstream of the air intakes. This creates a combined jet of the air sucked in and the blown jet, which is ejected on to the upper surface of the flap through outlet apertures located on the rear edge of the fixed part of the wing.

Abstract: The present invention is directed to the manufacture of and the use of an aerodynamic flow control device having a compact array of a plurality of fluidic actuators in planar, curved, circular and annular configurations. The compact array of fluidic actuators of the invention may be designed to produce oscillating or pulsed jets at the exit ports with frequencies in the range of 1-22 kHz. They may be integrally manufactured along with the wing sections, flaps, tail and rudder of airplane, the inlet or exit geometries of a jet engine. When supplied with a source of fluid such as air, these arrays of actuators produce a set of fluid jets of random phase of high velocity and influence the main stream of air over the subject surface. The beneficial effects of modifying flow using the present invention include increased lift, reduced drag, improved performance and noise reduction in jet engines.

Abstract: A high lift system with a main wing and regulating flaps, also bearing devices for the mounting of the regulating flaps, and positioning devices for the positioning of the regulating flaps, wherein the respective bearing device and/or positioning device is at least partially provided with a fairing, having a flow control device for purposes of controlling the flow around the high lift system with at least one inlet duct with at least one inlet, which device is located on or underneath the lower face of the high lift system, wherein at least one outlet duct for air is furthermore provided, which is connected with the inlet duct in a fluid-communicating manner, and has at least one outlet, which is located on the upper face in the region of at least one regulating flap of the high lift system.

Abstract: A method of using one or more microjets to create and/or control oblique shock waves. The introduction of microjet flow into a supersonic stream creates an oblique shock wave. This wave can be strengthened—by increasing microjet flow rate or the use of many microjets in an array—in order to form an oblique shock. Such an oblique shock can be used to decelerate flow in a jet aircraft engine inlet in a controlled fashion, thus increasing pressure recovery and engine efficiency while reducing flow instability. Adjusting the pressure ratio across the microjet actually alters the angle of the oblique shock. Thus, the use of microjets allows decelerating shock waves in an inlet engine to be properly positioned and controlled. Microjet arrays can also be used to ameliorate shock waves created by external aircraft surfaces, such as sensor pods and weapons.

Abstract: A boundary layer energizer (20) for energizing a boundary layer flow (33) over a surface (22), the boundary layer energizer (20) comprising one or more passages (24) terminating in one or more respective holes (26) provided on the surface (22), wherein the one or more passages (24) comprises at least one fin (25) configured so as to generate a vortex flow in the one or more passages (24) such that, when in use, a fluid emanating from the one or more passages (24) flows in a vortex.

Abstract: An apparatus comprises a platform configured to move in a streamwise direction, an actuation unit associated with a control surface of the platform, a fluid source configured to supply an airflow to the actuation unit, and a control unit for moving an air jet across the control surface. The actuation unit is configured to form a traversing air jet pointing in the streamwise direction.

Abstract: A nacelle assembly for a turbine engine has a cowl for a turbine engine. The cowl has a first surface spaced from a second surface. The second surface defines defining a bypass flow passage. A flow volume is spaced between the first surface and the second surface. A plurality of holes are disposed on the cowl. Each of the plurality of holes are configured to alter local air pressure about one of the first surface and the second surface of the cowl. The plurality of holes are in communication with the flow volume.

Abstract: This invention relates to a method and system (10) for controlling the boundary layer of an airfoil (12) to reduce profile drag during flap deflection. The system (10) comprises first means for blowing air from a lower surface (14) of the airfoil (12) to trip airflow from laminar flow to turbulent flow during positive flap deflection; and second means for applying a suction force at the lower surface (14) of the airfoil (12) to preserve laminar flow during negative flap deflection.

Abstract: The present invention comprises a high performance, horizontal, zero-net mass-flux, synthetic jet actuator for active control of viscous, separated flow on subsonic and supersonic vehicles. The present invention is a horizontal piezoelectric hybrid zero-net mass-flux actuator, in which all the walls of the chamber are electrically controlled synergistically to reduce or enlarge the volume of the synthetic jet actuator chamber in three dimensions simultaneously and to reduce or enlarge the diameter of orifice of the synthetic jet actuator simultaneously with the reduction or enlargement of the volume of the chamber. The present invention is capable of installation in the wing surface as well as embedding in the wetted surfaces of a supersonic inlet. The jet velocity and mass flow rate for the SJA-H will be several times higher than conventional piezoelectric actuators.

Abstract: An unmanned aerial vehicle (UAV) has a payload or body affixed at one end of an elongated airfoil. The entire airfoil/payload combination rotates about a center of mass to define a rotor disk. Thrust is provided by air-augmented rocket engine thrusting tangentially at a location remote from the payload. A control system maintains knowledge of its environment, as by a camera, to produce directional control signals which actuate lift control means in synchronism with the rotational position of the vehicle. A deployable object may be carried. Protection of the stowed vehicle is provided by blister packaging.

Abstract: The invention is an aircraft that includes a flying wing having a plurality of extendable flaps mounted on the trailing edge of the flying wing. A canard is mounted on the nose of said flying wing. A system is mounted in the flying wing for providing high pressure air over the canard and the flaps. A second system is provided for controlling the flow of air over the canard to provide pitch control of the aircraft.

Abstract: Apparatus and methods provide for a controllable upper surface blown (USB) nozzle aperture. Aspects of the disclosure provide a powered-lift aircraft that utilizes a controllable nozzle aperture to maximize the spreading of the engine exhaust flow over the wing and USB flap surfaces to increase lift when desirable and to minimize exhaust plume contact with the wing and USB flap surfaces when minimizing drag is desirable. The controllable USB nozzle aperture includes movable upper, lower, and side duct surfaces to dynamically vary the geometry of the nozzle exit aperture to minimize the height and maximize the width of the exit aperture for maximum spreading of the exhaust plume or to maximize the height and minimize the width of the exit aperture for minimizing the spreading of the exhaust plume and minimizing the associated drag.

Abstract: An aircraft including a longitudinal fuselage, at least two lateral wings connected symmetrically one on each side of the fuselage and at least one engine pod fixed to each lateral wing via an engine support pylon. At least one profiled bearing rod is positioned on each of the engine support pylons so as to generate a propulsive resultant force under action of an oblique air flow.

Abstract: An STOL and/or VTOL aircraft comprises (1) a fuselage having a front end, a rear end and two lateral sides, the fuselage defining a substantially horizontal central longitudinal axis of the aircraft; (2) an aircraft tail arranged at the rear end of the fuselage and including a rudder and an elevator on each side of the fuselage with movable surfaces for controlling the aircraft; and (3) a wing on each side of the fuselage having a front edge, a trailing edge and an upper surface extending from the front edge to the trailing edge. According to the invention, a device is provided for increasing the speed of an airstream flowing over the upper surfaces of the wings as compared to the speed of the airstream flowing over the lower surfaces thereof. Such means comprise openings in the upper surfaces of the wings for the egress of air from interior spaces within the wings and air pump apparatus for pressurizing such interior spaces.

Abstract: A system and method for control of a fluid flow. The system includes an array of interdependent fluidic actuators, each including a chamber, a flow control port, and opposite side walls configured to expand apart and contract together to flow a control fluid through the flow control port in response to an input, wherein adjacent actuators in the array of interdependent fluidic actuators are integrally coupled together via a common side wall of the opposite side walls.

Abstract: A purging system for a laminar flow control system comprises an air scoop and a diffuser fluidly connected thereto. The air scoop is disposable into an external flow of an external atmosphere. The diffuser is configured to fluidly connect the air scoop to a suction cavity of the laminar flow control system wherein the suction cavity may be disposed adjacent a porous skin of an airfoil such as adjacent a leading edge of the airfoil. The laminar flow control system may be configured to suction boundary layer flow passing over the porous skin by drawing a portion of the boundary layer flow through a plurality of pores formed in the porous skin. The diffuser ducts high pressure flow captured by the air scoop to the suction cavity for discharge through the pores to reduce the potential of blockage thereof.

Abstract: A high-lift flap of an aircraft is provided having a device for influencing the flap vortex as well as a device for influencing the flap vortex at the lateral edge of the aerodynamic high-lift flap, which can be achieved effectively and at low cost.

Abstract: A propulsion system for an aircraft includes an airfoil, an engine having an engine cowling carried by the airfoil and configured to produce exhaust gases that are predominantly directed toward an aft end of the airfoil by the engine cowling as engine exhaust, a propulsion flap carried by the airfoil and disposed aft of the engine cowling and a plurality of exhaust ejection orifices provided in the propulsion flap and adapted to receive at least a portion of the exhaust gases from the engine cowling.

Abstract: An air discharge device includes a grid that is connected to an aerodynamic surface of an aircraft. The grid includes a number of openings delimited by intermediate zones that are arranged in the extension of the aerodynamic surface of the aircraft and at least one longitudinal reinforcement separating the openings into at least two stages. The dimensions and/or the surface ratio of the perforated zones that correspond to openings and non-perforated zones that correspond to intermediate zones or to the longitudinal reinforcement are such that they create a depression close to the air discharge.

Abstract: An air vehicle includes an airfoil designed for transonic flight. The airfoil has a region of supersonic flow during transonic flight. A surface of the airfoil has upstream and downstream orifices at or within the region. The air vehicle further includes an active flow control system for controlling air vehicle motion during transonic flight by controlling flow through the orifices to alter strength and location of a shock wave in the region. The system creates an aerodynamic imbalance to move the shock wave.

Abstract: Apparatus and methods provide for an aircraft configuration that utilize structural and engine exhaust flow control devices to enhance performance. Aspects of the disclosure provide a fuselage with a pressure vessel nested within a non-cylindrical outer mold line fairing. A twin-boom empennage may be connected to the fuselage. A wing may attach in a blended wing configuration with a sweep angle that positions the aircraft center of lift to minimize any pitching moment induced by the activation or deactivation of an upper surface blown (USB) system. The USB system may include a conformal USB flap positioned downstream of an engine exhaust plume, as well as a controllable USB nozzle aperture to promote exhaust flow attachment to the conformal USB flap. A universal convergent nozzle may be utilized to connect each controllable USB nozzle aperture to a corresponding internally mounted aircraft engine.

Abstract: The present invention provides a system and method for actively manipulating and controlling aerodynamic or hydrodynamic flow field vortices within a fluid flow over a surface using micro-jet arrays. The system and method for actively manipulating and controlling the inception point, size and trajectory of flow field vortices within the fluid flow places micro-jet arrays on surfaces bounding the fluid flow. These micro-jet arrays are then actively manipulated to control the flow behavior of the ducted fluid flow, influence the inception point and trajectory of flow field vortices within the fluid flow, and reduce flow separation within the primary fluid flow.

Abstract: A system and method for generating lift provided by a multi-element aircraft wing are provided. The system includes a main wing element, a slat interconnected to the main wing element, and a flap interconnected to the main wing element. The system also includes at least one port defined in at least one of the slat, main wing element, and flap. In addition, the system includes at least one fluidic device operable to regulate fluid flow into and out of the at least one port to control boundary layer flow over at least one of the slat, main wing element, and flap.

Abstract: An aircraft with a fluid-duct system for extraction of the laminar layer and/or blowing out of fluid at vulnerable places of the outer skin, wherein the fluid-duct system (26, 19, 18) by means of switchable valves (6, 4) is connectable to a pump facility (3), which is driven by the exhaust air from the cabin for generating a reduced pressure for the extraction of the laminar layer.

Abstract: A method and device are provided for manipulating high-speed flows without moving aerodynamic structures. More particularly, a flow control actuator device is provided that is capable of producing a pulsating synthetic jet with high exhaust velocities for manipulating high-speed flows without moving aerodynamic structures. The high exhaust velocities of the actuator device may reach sonic levels of Mach 1 or greater. In one embodiment, the device may be constructed as an array of devices. In such an embodiment, each individual device is preferably reduced to a very small size. In such an embodiment, each individual device can then be fired in temporal patterns to create high-speed synthetic jets of air extending above the surface of the each device.

Abstract: A flow control actuator 10 for a body exposed to fluid flow comprises first and second flow surfaces 14, 16 spaced to define an elongate gap 20 therebetween. An elongate control element is disposed in or adjacent the gap and has an externally facing arcuate surface and defines a first slot 24 between the control element and said first flow surface and a second slot between said control element and said second flow surface 26. The control element 22 is moveable to allow the width of said slots to be adjusted generally proportionally. The flow of pressurized flow control fluid passes from a plenum chamber 30 out through one or both slots 24, 26 to be deflected around the arcuate surface under the influence of the Coanda effect. The flow control actuator 10 may be provided in the trailing or leading edge of an aerofoil; alternatively it may be provided between two surfaces spaced to provide said gap but otherwise providing a generally continuous surface.

Abstract: An air pump positioned within a hollow space in an aerodynamic structure for controlling the flow over an aerodynamic surface thereof, includes a movable member linearly displaced by a very low friction piston mechanism and a compression chamber open to the exterior of the aerodynamic surface through an orifice. Reciprocal displacement of the very low friction movable member changes the volume of the compression chamber to alternately expel fluid (e.g., air) from and pull fluid into the compression chamber through the orifice. The movable member includes a piston oscillating within a piston housing each having an ultra-low friction coating for improved thermal performance and reduced maintenance. Fluid intake to the compression chamber may be increased through the use of a one-way valve located either in the aerodynamic surface, or in the piston. Multiple flapper valves may surround the orifice in the aerodynamic surface for increased fluid control.