Abstract: Apparatus for generating vortices to control the flow of air across a airfoil of an aircraft includes a series of pressure active regions arranged along the leading edge of the airfoil. The pressure active regions include spaced apart valves connected to a source of vacuum, a controller for activating the valves, and sensors for sensing air pressure. The controller is configured to activate the valves in response to the pressure sensed by the sensors, wherein the spaced apart valves are connected to a source of pressurized air as well as to the source of vacuum.

Abstract: A method for inhibiting dynamic stall of an airfoil by causing a fluid to flow out of at least one location on the airfoil. This location may be anywhere on the airfoil; but if the location is within one-quarter of the airfoil chord from the leading edge and the fluid flow has non-zero net mass flux, then the fluid flow is modulated at a frequency described by a Strouhal ratio greater than one.

Abstract: Porous surfaces on an aerodynamic structure driven with positive and negative pressures are used in an active control system for attenuating shock waves responsible for high-speed impulsive (HSI) noise. The control system includes an array of apertures in the outer skin of the structure providing fluid communication between the exterior flow stream and an interior volume of the structure. A movable diaphragm within the structure pushes air out of and pulls air in through the apertures under the action of a drive mechanism within the structure, thus creating oscillating air jets. The drive mechanism may be actuated by a controller based on information supplied by a sensor in the leading edge of the aerodynamic structure. The array of apertures may be spaced apart along the outer skin of the aerodynamic structure so as to span a distance of about 15% of the chord length. The oscillating airjets may be provided on multiple surfaces of the aerodynamic structure, including the upper and lower surfaces.

Abstract: A system for achieving a boundary layer control by sucking at least a portion of the boundary layer air flow through perforated or porous suction areas on the outer skin of the wings or other areas of the aircraft, includes one or more jet pumps (7) arranged in the bypass engine (5) of the aircraft, and a system of suction conduits (4) connecting the jet pumps (7) to suction channels (3A) communicating with the perforated or porous suction areas (3). Each jet pump (7) includes an ejector pipe (101) that is driven by an external surrounding driving jet (8) or by an internal driving jet (8) flowing through an internal jet pipe (15). The jet pumps (7) are arranged at selected locations in the air intake upstream of the fan, in the bypass channel (18) just downstream of the fan, in the bypass channel near the outlet end thereof, in the core hot gas channel (19) upstream of a compressor assembly, and/or in the core channel downstream of a turbine assembly.

Abstract: An apparatus serves for influencing the separation of a flow 2 from a body 1 immersed in the flow. The apparatus excites a shear layer 11 of the flow 2 at the immersed body 1 by periodic blowing and suction in order to act against further separation of the shear layer 11 from the immersed body 1. For this purpose, the apparatus has at least one passive cavity resistor 46, the hollow cylinder 4 of which has at least one opening 6 leading to the surface 10 of the body 1. The cavity resonator 46 is excited by the flow 2 thus creating compressional vibrations, and the compressional vibrations of the cavity resonator 46 excite the shear layer 11.

Abstract: An aircraft wing, wing assembly and method of reducing drag are provided. The wing asembly includes a main wing portion (10) and a leading edge high lift portion (12). The high lift portion is movable between a retracted position in which it generally merges with the main wing portion and a deployed position forwardly thereof. At least a substantial part of an upper surface (22) of the high lift portion is air permeable or perforated and in flow communication with a suction passage (30) in it. In flight, suction may be applied to the suction passage to reduce the chordwise extent of the turbulent boundary layer over the upper or lower wing surface.

Abstract: The present invention relates to the field of aerohydrodynamics and heat and mass transfer and especially relates to a method and an apparatus for controlling the boundary layer or the wall layer of a continuous medium consisting of gases, liquids and/or their mixtures in the vicinity of a surface (1) for changing the flow structure, turbulence level, transfer of the impulse, transfer of heat and/or admixtures by influencing of the flow and changing of the velocities of the continuous medium particles.

Abstract: A jet engine has a noise reduction system which reduces the boundary layer located on the outer surface of the nacelle. The noise reduction system includes a plurality of openings located in the outer surface of the nacelle which are in communication with a source of low pressure. The low pressure causes a reduction in the boundary layer at the openings so that resulting ambient air flow velocity near the nacelle surface is increased. This causes a reduction in the shearing between the secondary and ambient airflows thereby reducing the noise.

Abstract: A passive porosity management device and process for an airfoil which provides a mechanism and method for controlling and modifying the lift, drag and flow field characteristics on an airfoil through the controlled seepage and transference of air utilizing passive porosity through one or more regions of an airfoil and into, and out of, one or more plenum cavities disposed in the interior portion of the airfoil.

Abstract: A vehicular boundary layer control system utilizing a series of external perforation arrays and suction sources controlled by a digital signal processor or microprocessor. Each array of perforations in the outer vehicle skin is served by a plenum chamber, which is selectively isolable from a suction manifold. The desired vacuum for each individual plenum and associated array is determined through the sampling of the turbulence associated with that array as well as other sensed environmental parameters. Vacuum is maintained at the desired level in each plenum through the arbitration of various suction sources and the selective restriction of airflow from the plenum(s) to the suction manifold. For terrestrial aerodynamic vehicles, a series of moisture separators are included in the plenums to mitigate the effects of any ingested moisture.

Abstract: A passive transpiration system for controlling interaction between turbulent boundary layer air and an impinging shock during supersonic airflow by application of a panel including passively activated mesoflaps that direct air circulation through a cavity in response to supersonic airflow. The mesoscopic flaps are preferably arranged in a matrix on one side of a cavity. The flaps deflect to allow air to circulate through the cavity during supersonic airflow, thus controlling the interaction between boundary layer air and air from the impinging shockwave. The flaps open to varying degrees depending on the speed of the airflow. The preferred structure includes channel sidewalls arranged parallel to one another and open on one end, creating multiple cavities. The sidewalls are connected by struts. Rows of flap support beams are connected to the sidewalls. The flaps are connected on one end to the beams, enabling them to deflect over their remainder in response to aerodynamic pressures.

Abstract: The present invention involves a system for altering the aerodynamic shape and/or fluid flow field about a solid body. The preferred embodiment comprises a synthetic jet actuator embedded in a solid body, with the jet orifice built into the body surface. The synthetic jet actuator generates a series of fluid vortices emanating from the orifice so as to entrain fluid external to the actuator chamber and form a synthetic jet stream. A recirculating flow region is formed along the solid body surface about the synthetic jet orifice. As a result the apparent aerodynamic shape of the body is altered. Consequently, if the solid body is placed in a fluid flow field, the entire fluid flow field is altered by the operation of the synthetic jet actuator.

Abstract: Boundary layer air on the skin structure of an aircraft is sucked off through suction holes in the aircraft skin structure by a least one ejector pump. The ejector pump is operated by at least one of several air flow sources. One source is the excess pressure in the passenger cabin at higher altitudes. The other air flow source is tap air from at least one aircraft engine. If necessary, one or the other or both air supply sources may be utilized to operate the ejector pump or pumps.

Abstract: A passive porosity airfoil lift management device employed on a leading edge region of said airfoil whereby the lift on said airfoil may be varied and controlled by passively transferring air pressure between the upper surface and lower surfaces of said leading edge region of the airfoil through upper and lower porous skin regions, upper and lower plenum cavities disposed in said airfoil, and controllably monitoring and regulating said passive air pressure transference with at least one valve and a microprocessor.

Abstract: A system and method for reducing skin friction of an object in relative motion to a fluid. A skin forming a boundary between the object and the fluid, the skin having holes through which micro-blowing of air is blown and a transmitting mechanism for transmitting air through the skin. The skin has an inner layer and an outer layer, the inner layer being a low permeable porous sheet, the outer layer being a plate having high aspect ratio high porosity, and small holes. The system may further include a suction apparatus for suctioning air from the outer layer. The method includes the steps of transmitting air through the inner layer and passing the air transmitted through the inner layer to the outer layer. The method may further include the step of bleeding air off the outer layer using the suction apparatus.

Abstract: The method for damping global flow oscillations (20a.x, 20b.x) in a flowing medium in the region of an unstable flow (10) separating itself from at least one boundary surface (11, 12) is comprised of detecting the global flow oscillations with a sensor system (13) and superimposing a compensatory oscillation (15, 16) controlled by the signals of the sensor system onto the flowing medium in a separation zone of the separated unstable flow. Correspondingly, the apparatus for performing the method comprises a generator (17, 18) which superimposes a compensatory oscillation on the flowing medium in a separation zone of the separated unstable flow and a control system (28, 29) which evaluates the signals of the sensor system and controls the compensatory oscillation so that the amplitude of the global flow oscillation is damped by a prespecified factor.

Abstract: An improvement to boundary layer control system, including a transpiration panel (58) for transpiring suction air in a distributed manner, is provided. The transpiration panel (58) replaces the discharge nozzle of prior art flow control systems. The transpiration panel (58) is generally a rigid panel having a plurality of small holes (62) extending from an inner panel surface (56) to a smooth outer panel surface (54). The transpiration panel (58) is positioned flush with an external aircraft surface in a region where laminar flow control is not being attempted. Exemplary subsonic and supersonic boundary layer control systems including the transpiration panel (58) are provided. A preferred location of the transpiration panel (58) for the subsonic application is the underside of a wing (80), near the leading edge. A preferred location of the transpiration panel (58) for the supersonic application including on the upper surface of a wing (114) near the fuselage (118), in a turbulent wedge region.

Abstract: An aerodynamic low drag structure (12) has a skin (18, 19, 20) which in movement of the structure (12) relative to a surrounding gaseous fluid medium produces at a flow control region of the skin (18) laminar flow in a boundary layer adjacent the skin. To improve boundary layer control, gaseous fluid is withdrawn from the boundary layer at the flow control region into a first inlet opening (21, 22, 23) in the skin (18) and is conveyed along a first fluid flow path (241, 242) within the structure (12) for discharge at a discharge opening (28) downstream of the first inlet opening (21, 22, 23). Gaseous fluid is withdrawn at a second inlet opening (26) in the skin (20) at a region of the skin subjected to gaseous fluid at ramming pressure and conveyed along a second fluid flow path (27, 242) within the structure to the discharge opening (28) or a further discharge opening.

Abstract: Aircraft apparatus and method capable of V/STOL (vertical, short takeoff and landing) in addition to conventional flight. For V/STOL operation, induced lift is provided by blowing air over the upper surface of each wing through a duct installed near the leading edge. Intake air is supplied to the blowing fan through a duct installed near the trailing edge, thus providing suction as well as blowing. Two fans in series are required. The engine provides power not only to the propeller but also to a transmission which provides power to the pulleys driving the belt-driven fans.

Abstract: A porous material is manufactured by weaving polycarbonate fibres through a tow of carbon fibres which has been pre-impregnated with an epoxy resin. A second layer of pre-impregnated carbon fibres are superimposed on the woven layer and the epoxy resin is cured to bond the fibres together. A ceramic slurry is applied and allowed To penetrate through the second layer of fibres and part way through the woven layer of fibres to a controlled depth before being dried to form a mask. A thermoplastic powder is then applied to the unmasked region of the woven layer of fibres and sintered. Finally the mask and the polycarbonate fibres are removed chemically to produce a porous material which comprises a sintered thermoplastic layer reinforced with carbon fibres through which channels are provided.

Abstract: A perforated sheet is diffusion bonded to a thin solid sheet. Each of the perforations of the perforated sheet is tapered, having a maximum diameter at the surface that is not bonded to the thin sheet and a smaller diameter at the surface that is bonded to the thin sheet. The bonded perforated sheet and thin sheet are included with other solid metallic sheets in a forming pack to be superplastically deformed into a structure. The bonded perforated sheet and thin sheet are placed on the top of the forming pack so that the thin sheet will face outwards after the structure is formed. After the superplastic deformation process is completed, the thin sheet is removed by machining to expose the perforated sheet and provide a structure for controlling laminar flow over the perforated sheet. The exposed surface of the perforated sheet includes the smaller diameter of each tapered perforation, while the inner-facing or blind surface of the sheet includes the maximum diameter.

Abstract: Apparatus and method for airflow vectoring control for an airfoil, a two dimensional jet, and the like. An airfoil or jet with a blunt open edge and a suction system for sucking air into the open edge. A blower system for blowing air out through the open edge. A control for changing the direction of flow through the open edge. A baffling arrangement for changing the magnitude and distribution of flow across the open edge.

Abstract: A method and apparatus for boundary layer control by sucking air off the vortex chambers established in the trailing-edge portion of an aircraft aerodynamic surface. The rate of air bleed is controlled first by increasing it until the boundary layer is attached to the airstreamed surface, then by decreasing the rate of air bleed until the pressure in the trailing-edge aircraft portion starts decreasing. The aircraft equipped with the boundary layer control system, including a number of vortex chambers accommodating streamlined bodies and communicating, through a common passage and a receiver, with a low-pressure source.

Abstract: A flight vehicle includes a base frame in which an accumulating tank is mounted for receiving air. An air entrance device is mounted on the first end of the base frame for introducing air to enter into the accumulating tank. A power supply device is mounted in the base frame for pressurizing air in the accumulating tank. A nozzle device is mounted on an upperside of a first end of the base frame and communicates with the accumulating tank for injecting the pressurized air therefrom along a longitudinal direction of the base frame. A suction device is adjustably mounted on an upperside of a second end of the base frame and is restricted to be disposed between a first position where air injected from the nozzle device is introduced into the suction device and a second position where the suction device stops operating. An elevator device and a rudder device are respectively mounted on an upperside of the second end of the base frame. A wheel assembly is mounted on an underside of the base frame.

Abstract: A supersonic aircraft having highly swept subsonic leading edge portions of the wings provided with boundary layer control suction slots. When the airplane is operating at high angles of attack under circumstances where noise is objectionable, air is drawn in through the suction strips to alleviate separated air flow and substantially eliminate (or at least alleviate) vortices that would otherwise develop over the upper wing surface. This improves the L/D ratio and permits the engines to be at a lower power setting, thus alleviating noise. There are shown a double delta planform configuration, and an arrow plan form configuration. Also, the boundary layer control suction can be used in conjunction with laminar flow control suction.

Abstract: An aircraft wing having a super critical profile is equipped with a venting device extending in the direction of the span width along the upper side of the wing. The ventilating device includes a compensation chamber in the wing and the chamber is covered with a perforated wall strip on both sides of the compression shock. The forward end of the compensation chamber has a gap shaped exit for blowing out the venting medium in the flow direction of the flow across the wing tangentially to the wing.

Abstract: A laminar flow control arrangement for use in a nacelle for an aircraft turbine engine. The nacelle has a microporous outer skin in the area where air flow over the skin is to be maintained in laminar flow. A honeycomb core is bonded to the inner surface of the nacelle skin. A perforated back skin is bonded to the inner surface of the core. Several closely spaced circumferential flutes open to the back skin are fastened to the back skin. At least one collector duct is connected to the flutes and a suction pump. In operation, the suction pump pulls air through the ducts and flutes, causing air to be sucked inwardly through the microporous skin thereby maintaining laminar, rather than turbulent, flow over a large part of the nacelle during aircraft take-off and cruise operation. In addition, a chamber is preferably provided in communication with any gaps in the nacelle skin in the area where laminar flow is desired.

Abstract: In the present method boundary layer thickening is combined with laminar flow control to reduce drag. An aerodynamic body is accelerated enabling a ram turbine on the body to receive air at velocity V.sub.o. The discharge air is directed over an aft portion of the aerodynamic body producing boundary layer thickening. The ram turbine also drives a compressor by applying torque to a shaft connected between the ram turbine and the compressor.The compressor sucks in lower boundary layer air through inlets in the shell of the aircraft producing laminar flow control and reducing drag. The discharge from the compressor is expanded in a nozzle to produce thrust.

Abstract: A basic airfoil has its operating performance improved by incorporating one or more apertures in the airfoil adjacent its trailing edge. These apertures extend from the upper surface of the airfoil down through to the lower surface of the airfoil. The entry port and the exit port of these apertures has a greater circumference than that of the throat circumference which is intermediate thereto. This structure forms a venturi having a vertical axis. Spaced below the throat of the aperture are a plurality of air nozzles that communicate with an air plenum chamber within the airfoil. A source of pressurized air is connected to the plenum chamber. The leading edge of the airfoil causes air to flow across both the upper surface and lower surface of the airfoil. The venturi creates a strong suction on the upper surface of the airfoil to enhance the airfoil's pressure differential.

Abstract: A method and an apparatus for influencing a laminar-turbulent boundary layer transition on bodies in flow is indicated. The disturbances are in this case introduced into the boundary layer in an unsteady manner. The disturbances are induced by blowing-out and sucking-off and/or by oscillations of the surface and/or by sound pressure.

Abstract: A method and apparatus for reducing the skin friction on objects in relative motion to a field of fluid. The areas of relative low speed motion are fixed to align with a series of ridges on the surface of the object. The areas of low speed motion aligned with the ridges are removed by suction from the turbulent boundary layer which results in a reduction of drag on the object. An alternative embodiment injects fluid into areas of relative high speed between the ridges to reduce the shear and the drag caused by it. Selective suction and injection are combined in one apparatus in a second alternative embodiment. A fourth embodiment injects a polymeric solution to reduce drag. A fifth embodiment heats the fluid in specified areas to reduce drag. A sixth embodiment uses a compliant material in specified areas of the surface in contact with flowing fluid to reduce drag.

Abstract: A rotorcraft is provided with laterally placed dual rotors which rotate in opposite directions with the axis through the center of the rotors being transverse to the longitudinal axis of the aircraft's fuselage. Between the two rotor hubs a wing structure is placed above and below the blades with the two wings joined together forming a leading edge outward of the blades' radius toward the designated front of the craft thus forming a sheltered wing structure that allows the two rotors to revolve in their retreating mode phase out of the air stream when the craft is in horizontal flight. A compressed gas ejection system would aid in the transition of the blades from operating in free air to operating within the sheltered wing structure. A louver system in the upper and lower wings would operate to allow air flow freely through the wing during the lifting or hovering mode.

Abstract: By controlling the flow of the air over an airfoil, a lifting force can be achieved even in the absence of forward motion by the aircraft. The air flowing over the airfoil is forced into a chamber by a propulsion unit and the air entrapped in the chamber can be recirculated to a forward portion of the airfoil lifting surface, thereby increasing the lifting force of the airfoil. The lifting body has side members associated with the airfoil to channel the air over the airfoil. Outlets from the chamber are provided to direct the flow of air in any lateral direction for assistance with directed motion or for assistance with aircraft stability. Additionally, outlets in the bottom of the aircraft can assist in the vertical force exerted on the aircraft by forced air escaping therefrom.

Abstract: A low drag surface construction utilizes a plurality of longitudinally extending, parallel, spaced apart linear vortices extending transversely of the free stream to reduce drag between the free stream and the surface. The surface is provided with stabilizing means which retains the vortices in their relationship with one another but causes them to traverse the surface in the same direction as the free stream but at approximately half the speed. The stabilizing produces a regular variation in boundary flow across the surface and may comprise dynamic means such as sequenced jets of fluid escaping from apertures in the surface.

Abstract: Separated laminar flow boundary layers are stabilized by delaying a transition into a turbulent flow and by reducing the size of the laminar boundary layer separation zone downstream of a disturbance in the surface contour of a body in the flow, such as a backward step in the body surface, e.g., where sheet metal layers overlap in the surface of an aircraft wing. This purpose is accomplished by suction inlets in the surface just upstream of the disturbance and blowing outlets just downstream of the disturbance and by a flow channel interconnecting these inlets and outlets. Passage of a portion of the flowing medium through these passages is automatically assured due to a pressure differential between the inlets and outlets.

Abstract: An airfoil for transonic speeds includes a porous top surface extending from a location about 50 to 60% of the chord length from a leading edge of the airfoil to a location about 80 to 90% of the chord length from the leading edge. A cavity is defined under the porous surface in the airfoil which has a depth of from 0.05 to 0.2% of the chord length. The porosity of the porous surface is chosen to be from 1 to 3% of the total airfoil surface and may be variable. The presence of the porous surface and cavity decrease airfoil drag at transonic speeds by providing a pathway between a high pressure area downstream of a shock wave formed on the airfoil at transonic speeds to a low pressure area within a bubble on the airfoil upstream of the shock wave.

Abstract: Aircraft engine exhaust is mixed with air and fuel and recombusted. Air is drawn into the secondary combustion chamber from suction surfaces on wings. Exhaust of the secondary combustion chamber is blown over wing and fuselage surfaces.

Abstract: A capture device at the tip of a fluid foil such that when the foil has relative motion with respect to fluid in which it is immersed the capture device intercepts a quantity of the crossflow which is generated by the difference in pressure on the lower surface relative to the upper surface so that lift-induced drag is reduced thereby. The capture device comprises a curved plate having its concave side facing inward toward the foil center span to form an inlet, and an aspirating device for venting off the lower surface crossflow inducted by the capture device. Conventional pumping can be used to aspirate the capture device or a winglet having a passage connecting the capture inlet with a slot opening on a low pressure region of the winglet can be utilized for the purpose.

Abstract: Aircraft engine exhaust is mixed with air and fuel and recombusted. Air is drawn into the secondary combustion chamber from suction surfaces on wings. Exhaust of the secondary combustion chamber is blown over wing and fuselage surfaces.

Abstract: A lift augmenting device to provide a vertical take-off capability in aircraft which includes a pair of rotor assemblies with independently individually pivoted rotor vanes so that the attitude of the vanes can be changed at different positions along the circumferential rotational path of the vanes as they rotate with the rotor assemblies to pump air therethrough and selectively generate lift on the aircraft.

Abstract: A helicopter rotor is formed with spars and ribs. The spars form parts of the surfaces, and long slots are constructed in the spars to provide suction and blower slots. Air is withdrawn in slots nearest the leading edge, and engine exhaust is conducted to a suction/blowing device which in turn blows air through slots near the trailing edge. Helicopter engine exhaust is mixed with air and fuel and is recombusted. Air is drawn into a recombustion chamber of a suction/blowing device from suction surfaces on the helicopter rotor blades. This suctioned air is then re-routed to the slots near the trailing edge and blown over the upper and lower surfaces of the blade.