Abstract: A method and system 10 for controlling fluid flow 12 in relation to a body or foil 14. The system 10 has one or more channels 16, at least some of which having an inlet port 18 and an outlet port 20 defined in the foil 14 through which at least some of the fluid 12 may flow. The inlet port 18 is defined adjacent to a leading edge region 22 of the foil 14 and the outlet port 20 is located in a another region 24 of the foil. Optionally, a differential vectoring means 24 provides a differential mass flow rate across the foil 14 to provide a resultant force that in one illustrative environment creates, enhances, or stops a rolling action of the foil 14.

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: Methods and apparatus for controlling the attitude of a mobile platform with a resolution suitable for vernier attitude control. In one embodiment a method includes flowing fluid through an orifice of an aerodynamic surface. The method also includes modifying a boundary layer of the aerodynamic surface with the flowing fluid. Another embodiment provides an aerodynamic member of a mobile platform. The aerodynamic member includes an aerodynamic surface, an orifice, an actuator, and a fluid moving member. The orifice is in the aerodynamic surface and the actuator is subject to friction and backlash. The fluid moving member communicates with the orifice and causes the fluid to flow through the orifice to modify the boundary layer of aerodynamic surface.

Abstract: An aerodynamic body of an aircraft with an air outlet opening and an air intake opening that communicates with the air outlet opening via an air conduit is described. A flow delivery driver device for influencing the flow within the air conduit is integrated into the air conduit. The surfaces of the aerodynamic body in the body chord direction include at least one air outlet opening in the front region of the aerodynamic body, and at least one air intake opening on the upper surface of the aerodynamic body and in the rear region of the aerodynamic body and/or on the upper surface of the aerodynamic body in the trailing edge region and/or on the lower surface of the aerodynamic body in the trailing edge region. Arrangements of a main wing and an adjustable flap, and an aircraft with such an aerodynamic body are also described.

Abstract: A system and method for drag reduction allows thrust output, fuel efficiency or both to be maximized. Specifically, a rear portion of a body or motor vehicle may be modified to increase thrust output, fuel efficiency or both by creating a stagnation area, a suction inlet and a convex cusp area formed on the rear portion of the motor vehicle. Increasing the concavity or camber or sharpness of the radius of the stagnation area results in greater local pressure coefficient, which results in greater thrust output. The size and shape of the suction inlet and the convex cusp area will also have an effect on thrust output and fuel efficiency. A width and volume of an airplane fuselage may be increased.

Abstract: A wing of an aircraft is described, having: a main wing, at least one high lift flap which can be moved between a retracted and an extended position, and a spoiler. The main wing has ejection openings, arranged side-by-side along the main wing spanwise direction, and in the main wing chordwise direction, and which are connected via an air conduit with the outlet device of a flow delivery driver device on the main wing or on the spoiler. The spoiler has inlet openings for the intake of air, which are connected via an air conduit with the inlet device of the flow delivery driver device. The flow delivery driver device has a receiver device for the reception of command signals for purposes of adjustment of the flow delivery driver device. An arrangement of a wing with a device for purposes of flow control with such a wing is also described.

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: A control device (16) for a wing (10) comprises an airbox assembly (16) connected to an aerofoil wing tip (17). The airbox assembly (16) includes passages (23) that receive air from the lower surface of the aerofoil (10) and accelerate and exhaust the air upwardly, outwardly and rearwardly of the aerofoil (10). This reduces or prevents the formation of wing tip vortices and so reduces induced drag. In addition, the airbox assembly (16) also includes a wing tip (17) of increased camber relative to the wing (10) that changes the flow of air over the lower pressure surface (11) of the wing (10) to mirror that over the higher pressure wing surface (12) so reducing on eliminating bound trailing edge vortices. Such devices can be used on other foils that operate in fluid streams to provide a force.

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: A system for reducing overall drag of a mobile platform includes a surface on which an airflow forms a boundary layer and a generally normal shockwave. The airflow is at a first velocity that is one of transonic and supersonic. An oscillating jet injects and extracts a jet flow through the surface. The jet flow is at a second velocity that is substantially less than the first velocity. A recirculation region is upstream of the normal shockwave and is disposed at least partially in the boundary layer. The recirculation region is established at least by the oscillating jet. A generally oblique wave is established by the recirculation region and weakens the normal shockwave to reduce the overall drag experienced by the surface.

Abstract: Active systems and methods for controlling aircraft vortices are disclosed. An apparatus in accordance with one embodiment is directed to an aircraft system that includes an airfoil having first and second oppositely facing flow surfaces and a tip. The system can further include a vortex dissipation device carried by the airfoil, with the vortex dissipation device including an orifice positioned to direct a flow of fluid outwardly from the tip, an actuator operatively coupled to the fluid flow orifice and positioned to change a manner in which flow is directed outwardly from the tip, and a controller operatively coupled to the actuator to direct the operation of the actuator. The vortex dissipation device can be activated to accelerate the rate at which vortices (e.g., wing tip vortices) dissipate after they are generated, for example, by alternately pulsing flow inwardly and outwardly through the fluid flow orifice.

Abstract: The present invention provides an aircraft having one or more fixed wings in a flying wing configuration, where the aircraft further includes a high performance co-flow jet (CFJ) circulating about at least a portion of an aircraft surface to produce both lift and thrust.

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: An aircraft component, such as a wing, has perforations through an outer wall for boundary layer suction. In the space between the outer wall and inner wall partition walls form pressure channels and suction channels that are adjacent to each other and alternate, which channels communicate with the perforations. For example, alternating channels may be formed by a corrugated structure having trapezoidal corrugations providing a larger area for the suction channels than for the pressure channels. The pressure channels may be coupled to a hot-air reservoir by a control device, lines and valves, and the suction channels may be coupled to a vacuum reservoir, unless a short-circuit valve is used to cross connect the lines.

Abstract: An onboard system for a rotary wing aircraft detects a limit cycle oscillation in the tail mast and provides a timely indication of the limit cycle oscillation to an aircrew before serious damage to the airframe is likely to occur.

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: An inlet flow control system disposed within a nacelle includes a panel on an inner surface of that nacelle. The panel includes a noise attenuation layer that dissipates noise energy. A vacuum source generates a pressure differential across the noise attenuation layer for drawing airflow through the panel and away from an inner surface of the nacelle.

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: A method for suctioning the boundary layer at the surface (1) of an aircraft having an air-conditioning system (4), at whose flow-critical points of the surface multiple suction openings (2) are provided, the air quantity suctioned via these being discharged to the atmosphere again via at least one outlet (7) placed in a way favorable for flow, the air quantity suctioned from the surface (1) being fed to the air-conditioning system (4) of the aircraft, via whose outlet (7) the air quantity suctioned is discharged to the atmosphere together with the exhaust air of the air-conditioning system (4), to reduce flow losses.

Abstract: A system and method for actively manipulating fluid flow over a surface using synthetic pulsators. Synthetic pulsators produce pulsed jet operable to manipulate the primary fluid flow proximate to the synthetic pulsator. The synthetic pulsator includes a dual diaphragm synthetic jet coupled to high performance dual actuator solenoids, wherein the synthetic jet is operable to produce an oscillatory flow. The oscillatory flow of the synthetic jet(s) produces the pulsed jet operable to manipulate the primary fluid flow. These synthetic pulsators may then be 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: An aerodynamic system providing an airfoil having a chord length, a leading edge, and a trailing edge. The airfoil further includes a first airfoil surface extending from the leading edge to the trailing edge, a second airfoil surface opposite the first airfoil surface, extending from the leading edge to the trailing edge, an injection opening in the first airfoil surface, and a recovery opening in the first airfoil surface located between the injection opening and the trailing edge. A pressurized fluid source is in fluid communication with the injection opening and a vacuum source is in fluid communication with the recovery opening. An exemplary use of the aerodynamic system of the present invention provides the ejection of a mass of fluid out of the injection opening along a surface of the airfoil and drawing a mass of fluid into the recovery opening.

Abstract: An aircraft component, such as a wing, has perforations through an outer wall for boundary layer suction. In the space between the outer wall and inner wall partition walls form pressure channels and suction channels that are adjacent to each other and alternate, which channels communicate with the perforations. For example, alternating channels may be formed by a corrugated structure having trapezoidal corrugations providing a larger area for the suction channels than for the pressure channels. The pressure channels may be coupled to a hot-air reservoir by a control device, lines and valves, and the suction channels may be coupled to a vacuum reservoir, unless a short-circuit valve is used to cross connect the lines.

Abstract: The present invention provides a system and method for actively manipulating fluid flow over a surface using synthetic pulsators. Synthetic pulsators produce pulsed jet operable to manipulate the primary fluid flow proximate to the synthetic pulsator. The synthetic pulsator includes a synthetic jet actuator(s) operable to produce an oscillatory flow, and fluidic jet(s) operable to provide a continuous fluid flow. The oscillatory flow of the synthetic jet(s) and the continuous fluid flow of the fluidic jet(s) combine or mix to produce the pulsed jet operable to manipulate the primary fluid flow. These synthetic pulsators may then be 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: In order to establish laminar flow on the attachment line (18) of an aerofoil body, a duct entrance (27) is provided on the leading edge of the aerofoil body for receiving spanwise boundary layer flow BLt. The exit (23) of the duct is located spanwise downstream of the duct entrance (27). The boundary layer flow BLt enters the duct (23) and is discharged downstream. The height of the duct entrance (27) above the leading edge of the aerofoil body is greater than the depth of the boundary layer BLt and thus a fresh laminar boundary layer is established on the outer surface (20) of the duct which propagates spanwise along the surface to rejoin the leading edge of the aerofoil body.

Abstract: Methods and apparatus for controlling the attitude of a mobile platform with a resolution suitable for vernier attitude control. In one embodiment a method includes flowing fluid through an orifice of an aerodynamic surface. The method also includes modifying a boundary layer of the aerodynamic surface with the flowing fluid. Another embodiment provides an aerodynamic member of a mobile platform. The aerodynamic member includes an aerodynamic surface, an orifice, an actuator, and a fluid moving member. The orifice is in the aerodynamic surface and the actuator is subject to friction and backlash. The fluid moving member communicates with the orifice and causes the fluid to flow through the orifice to modify the boundary layer of aerodynamic surface.

Abstract: Air pressure distribution for airfoil lower and upper surfaces is utilized to divert airflow using ducts formed in space-curve shapes placed inside the airfoil volume, through span-wise located inlets from high pressure areas on the airfoil lower surface near the leading edge and through chord-wise spaced inlets on the side face of the airfoil wing tip correspondingly to the side face of the airfoil wing tip through chord-wise spaced outlets on the side face of the airfoil wing tip and to span-wise located outlets to the low pressure areas on the airfoil upper surface. Triboelectric materials on the wing surfaces are employed to static charge the air in drag. Inside the ducts, the employment of either triboelectric linings and materials, or HV-supplied electrodes, or both, help to static charge the diverted air flow to and from the airfoil wing tip side face to diffuse wing tip vortex core early.

Abstract: A system and method for controlling boundary layer flow over an aircraft wing are provided. The system includes at least one wing element, and a plurality of ports defined in the wing element and in fluid communication with one another. The system also includes at least one fluidic device operable to continuously ingest the fluid through at least one of the ports and eject the fluid out of at least one other port to control boundary layer flow of the fluid over the wing element.

Abstract: A system for reducing overall drag of a mobile platform includes a surface on which an airflow forms a boundary layer and a generally normal shockwave. The airflow is at a first velocity that is one of transonic and supersonic. An oscillating jet injects and extracts a jet flow through the surface. The jet flow is at a second velocity that is substantially less than the first velocity. A recirculation region is upstream of the normal shockwave and is disposed at least partially in the boundary layer. The recirculation region is established at least by the oscillating jet. A generally oblique wave is established by the recirculation region and weakens the normal shockwave to reduce the overall drag experienced by the surface.

Abstract: An inlet flow control system disposed within a nacelle includes a panel on an inner surface of that nacelle. The panel includes a noise attenuation layer that dissipates noise energy. A vacuum source generates a pressure differential across the noise attenuation layer for drawing airflow through the panel and away from an inner surface of the nacelle.

Abstract: The present invention is directed to a distributed active flow control (“DAFC”) system that maintains attached airflow over a highly cambered airfoil employed by an aircraft or other similar applications. The DAFC system includes a primary power source comprised of one or more aircraft engines, one or more power conversion units, and optionally, one or more auxiliary power units. The power conversion units are coupled to one or more aircraft engines for supplying power to a distribution network. The distribution network disperses power from the one or more power conversion units to active flow control units disposed within one or more aircraft flight control surfaces (e.g., the aircraft wing, the tail, the flaps, the slats, the ailerons, and the like). In one embodiment, an auxiliary power unit is included for providing a redundant and auxiliary power supply to the distribution network.

Abstract: A device and method for conversion of the energy of medium flows are provided. The proposed device and method ensure suppression of the vortex streams in the flow on the leg of its motion along the radially converging trajectories and concentration of the flow energy, which is expressed by the increase of its velocity and decrease of the summary area of the cross section of the converging trajectories. As the flow runs along the first system of helical trajectories the following takes place: the harmful secondary vortex jets continue attenuating, the degree of concentration of the flow energy increases and velocity components form in the flow, which correspond to natural vortex streams, for instance, tornadoes, whirlpools.

Abstract: An aerodynamic body comprising at least one power plant inlet positioned in proximity to, and in fluid communication with, a boundary layer transition location associated with a boundary layer fluid flow over a surface of said aerodynamic body, the one or more power plant inlets operable for extracting at least a portion of said boundary layer fluid flow, thereby reducing drag on said aerodynamic body.

Abstract: Methods and apparatus for controlling the attitude of a mobile platform with a resolution suitable for vernier attitude control. In a preferred embodiment, a method includes flowing fluid through an orifice of an aerodynamic surface. The method also includes modifying a boundary layer of the aerodynamic surface with the flowing fluid. Another preferred embodiment provides an aerodynamic member of a mobile platform. The aerodynamic member includes an aerodynamic surface, an orifice, an actuator, and a fluid moving member. The orifice is in the aerodynamic surface and the actuator is subject to friction and backlash. The fluid moving member communicates with the orifice and causes the fluid to flow through the orifice to modify the boundary layer of aerodynamic surface.

Abstract: A wing for an aircraft has a passive jet spoiler for providing yaw control by increasing drag on the wing. The spoiler comprises an inlet located near the leading edge of a lower surface of the wing and at least one outlet formed on the lower surface or on an upper surface of the wing. An internal passage connects the inlet and each outlet for allowing air to pass from the inlet to the outlet. The air exits the outlets generally normal to the respective surface of the wing, causing a laminar flow to separate from the surfaces downstream of each outlet. The separated flow increases the drag on the wing, producing a yawing moment on the aircraft. Selective placement of the outlets on the upper and lower surfaces limits undesirable roll and pitch moments. Valves are provided for selectively controlling the amount of air passing through the spoiler.

Abstract: A laminar flow nacelle for an aircraft engine (10) has an outer member (26) defining an aerodynamic shape. The nacelle (24) has an inner member (28) defining a chamber (30) with the outer member (26) of the nacelle (24). The outer member (26) of the nacelle (24) has a porous region (32) at a first region (34) of the outer member (26) and the porous region (32) allows a flow of fluid into the chamber (30). A duct (36) connects the chamber (30) to an aperture (38) in the outer member (26) at a second region (40) of the outer member (26) downstream of the first region (34). In operation the static pressure at the first region (34) is greater than the static pressure at the second region (40) such that the boundary layer of the fluid flows through the porous region (32) at the first region (34) through the duct (36) to the aperture (38) at the second region (40). The first region (34) extends between 10% and 20% of the chord length of the nacelle (24) from the highlight (42) of the nacelle (24).

Abstract: An active flow control device and method for improving the aerodynamic efficiency of airfoils. The device and method pertain to the application of hybrid intermittent suction or intake of low-energy boundary layer fluid into an airfoil through one or more inlet openings while also applying intermittent blowing or expulsion of fluid out of such an airfoil into the boundary layer through one or more outlet openings for the purpose of delaying or eliminating boundary layer separation.

Abstract: An apparatus comprising: an aerodynamic surface adapted for producing an adverse pressure gradient in a fluid flow; and a first pulse detonation actuator disposed adjacent the aerodynamic surface and adapted for impulsively detonating a fuel/air mixture to produce a pressure rise and velocity increase of combustion products therein, the aerodynamic surface having a plurality of separation control holes adapted for communicating combustion product flows from the first pulse detonation actuator to the aerodynamic surface for modulating separation of the fluid flow from the aerodynamic surface.

Abstract: Active flow control devices and methods are disclosed for improving the aerodynamic efficiency of airfoils. The devices and methods pertain to applying intermittent suction or intake of low-energy boundary layer fluid into airfoils in a manner delaying or eliminating boundary layer separation.

Abstract: An active control device is disclosed comprising an array of actively controlled oscillating air jets disposed on an aircraft structure. In a preferred embodiment, the device senses parameters associated with incipient unsteady aerodynamic excitation, such as free stream gusts, shed wakes in rotor and turbomachinery flows, or oscillatory motion of trailing edge control surfaces such as ailerons. These parameters are provided as input signals to a processor. Based on the input signals, the processor generates output signals that are used to operate the air jet array in a manner counteractive to the unsteady forcing. The air jet array can be used on numerous aircraft structures, including rotor blades, wings, engine inlets, engine exhausts, blunt surfaces and nozzles.

Abstract: A method and apparatus for active boundary layer control on an aerodynamic surface. One or more piezoelectric synthetic jet actuators operate as a boundary layer pump to ingest fluid along the surface of an aerodynamic object and discharge fluid tangentially to the fluid flow along the surface and/or at the trailing edge of the object to reduce drag and delay stall.

Abstract: A laminar flow control system for incorporation in, for example, an aircraft flying surface includes a suction panel comprising a perforated skin (20, 40) mounted on a base member (60), a plenum chamber (30) being in communication with a plurality of micro channels (90) formed in the top surface of the base member (60), the micro channels (90) being in communication with the holes (40) in the skin (20).

Abstract: In a method of controlling vortex breakdown on an aerodynamic surface, a vortex generated by the aerodynamic surface is continually monitored to identify a non-linear region where vortex breakdown occurs. A fluid jet is blown into the non-linear region to displace the vortex breakdown to a target location. A blowing parameter for the fluid jet is continually adjusted to continually direct the fluid jet into the vortex breakdown region and preferably ensure maximum positive feedback. The fluid jet is dynamically displaced toward the sensitive spot to maximize the effectiveness of the jet.

Abstract: The present invention involves a system for altering the aerodynamic shape and/or fluid flow about a solid body. The preferred embodiment comprises an obstruction disposed on the solid body and extending outwardly from the solid body into the fluid flowing over the solid body and a synthetic jet actuator embedded in the solid body such that said fluid flowing over the solid body encounters the obstruction before the synthetic jet actuator. The synthetic jet actuator includes a jet housing defined by walls, the jet housing having an internal chamber with a volume of fluid and an opening in the jet housing connecting the chamber to an external environment having the fluid, and a volume changing means for periodically changing the volume within the internal chamber so that a series of fluid vortices are generated and projected in the external environment out from the opening of the jet housing.

Abstract: A forebody 10 for an aeronautical vehicle 12 is provided. The forebody 10 includes an exterior wall 14 having a first half 16 and a second half 18. The first half 16 has a first porous section 20 and the second half 18 has a second porous section 24. The first half 16 and the second half 18 also have a first exterior side 22 experiencing a first fluidic pressure and a second exterior side 26 experiencing a second fluidic pressure, respectively. A hollow inner cavity 28 is fluidically coupled to the first exterior side 22 and the second exterior side 26 and allows fluid passage between the first exterior side 22 and the second exterior side 26 through the first porous section 20, the inner cavity 28, and the second porous section 24. The exterior wall 14 equalizes the first fluidic pressure with the second fluidic pressure. Additional forebodies and methods for performing the same are also provided.

Abstract: A porous surface on an aircraft structure driven with oscillating positive and negative pressures is used as an active control device for attenuating negative aerodynamic interactions. The porous surfaces can be driven with positive and negative pressures either continuously or when predetermined flight conditions are present. The porous surfaces can be used on rotor blades to reduce BVI noise in descent flight conditions. The porous surfaces can be configured on rotor blades for affecting blade variable twist in accordance with various flight conditions, and can further be incorporated for reducing rotor hub vibrations as well. Porous surfaces placed on aerodynamic surfaces below the rotor blades of a tiltrotor aircraft can attenuate or eliminate download and fountain flow conditions.

Abstract: A method and apparatus for active boundary layer control on an aerodynamic surface. One or more piezoelectric synthetic jet actuators operate as a boundary layer pump to ingest fluid along the surface of an aerodynamic object and discharge fluid tangentially to the fluid flow along the surface and/or at the trailing edge of the object to reduce drag and delay stall.

Abstract: Boundary layer control of a structural element in a fluid stream is achieved by the following operations: providing in such structural element at least one region equipped with micro porous structure by an electroforming technique; having a fluid stream flow through the external surface of the said at least one region, inwards or outwards with respect to the environment in which that element is placed.

Abstract: One aspect of the apparatus disclosed herein is a system for modifying an aerodynamic property of an aerodynamic surface in a fluid flow. The fluid flow could comprise a free stream fluid flow, or an internal fluid flow, such as in a nozzle, diffuser, or compressor. The system of the preferred embodiment comprises a synthetic jet actuator embedded in an aerodynamic surface. In one aspect, the aerodynamic surface may be a wing. The synthetic jet actuator typically has a jet housing defining a chamber, where the chamber is in fluid communication with the fluid. This fluid communication may be accomplished via an orifice in a wall of the housing. Additionally, a portion of said housing is preferably moveable such that the volume of the chamber can be adjusted. The system also comprises a device for changing the position of the moveable portion of the housing at a predefined frequency. In this way, the synthetic jet actuator is pulse modulated in order to enhance the synthetic jet actuator's performance.

Abstract: The nozzle of an acoustic jet directs high momentum flux gas particles essentially tangentially into the boundary layer of the flow in a diffuser, an engine air inlet, a jet engine gas flow path or on the suction surface of an airfoil, the gas particles in the chamber of the tangential acoustic jet being replenished with approaching low momentum flux particles drawn from the gas flow in a direction normal to the surface, thereby to provide a net time-averaged flow of increased momentum flux particles to defer the onset of boundary layer separation and/or reduce the thickness of the boundary layer. The acoustic jet is driven by a gas pressure oscillation generator which may be a loudspeaker, a resonant solenoid piston, a cranked piston, or the like.