Abstract: A method of reducing carbon monoxide and unburned hydrocarbon emissions in a gas turbine engine by bleeding hot air from the engine cycle and introducing it back into the engine upstream of the bleed location and upstream of the combustor inlet. As this hot inlet air is recycled, the combustor inlet temperature rises rapidly at a constant engine thrust level. In most combustors, this will reduce carbon monoxide and unburned hydrocarbon emissions significantly. The preferred locations for hot air extraction are at the compressor discharge or from within the turbine, whereas the preferred re-entry location is at the compressor inlet.

Abstract: A turbofan engine is provided with a core engine, a first fan and a second fan. First and second fan ducts are provided for bypassing a portion of the air flow leaving the fans around the core engine. One of these fan ducts has its inlet disposed downstream of the second fan, while the second duct has its inlet disposed between the first and second fan. Means are provided for varying the proportion of the flow of air among the fan ducts and core engine. Integrated, or separate coaxial nozzles are provided for receiving the flows from the individual fan ducts and core engine and exhausting these flows into the atmosphere.

Abstract: Apparatus for modulating the area of a gas turbine engine nozzle which provides for positive sealing between overlapping articulated flaps when the overlapped flap is axially slotted to receive a portion of the overlapping flap. An arcuate seal is attached to the overlapping flap by means of a floating connection, the overlapping flap dragging the seal therewith in the axial direction. A seat is mounted on either side of the slot to slidingly receive a pair of shoulders laterally extending from the seal. A portion of the seal is received within the slot and is so contoured as to partially define the nozzle flow path. A sleeve captures and supports the seal shoulders during their axial travel.

Abstract: A blade fabricated of a plurality of bonded filament laminates, at least one of the laminates characterized by a plurality of continuous, collimated filaments embedded in a different matrix at the blade tip than at the blade root. The matrices are characterized by different relative impact strengths.

Abstract: An improved method of operating a gas turbine engine is presented wherein engine-generated noise is maintained at a reduced level during reduced thrust operation. Fan speed is maintained at a constant level while fan nozzle area is increased. This maintains high inlet Mach numbers for reduced forward noise propagation and also permits reduced nozzle exhaust velocity for reduced shear noise. In another embodiment, airflow is increased by means of a fan blade pitch change or speed increase while the fan nozzle area is increased, yielding both a net reduction in engine thrust and noise.

Abstract: Drive means for connecting a gas turbine engine to its accessories are so constructed as to allow the accessories to be selectively positioned to any one of several predetermined circumferential positions about the perimeter of the engine. This feature permits convenient mounting of the same engine upon vehicles demanding radically different engine mounting arrangements.

Abstract: A flameholder apparatus for use in a gas turbine engine exhaust nozzle comprises at least one V-shaped gutter for holding a flame, with fasteners to mount the gutter to a nozzle support structure, the fasteners being accessible from the downstream flow direction and protruding into the gutter. To prevent the fasteners from overheating, the protruding portion is recessed in a heat shield affixed to the gutter and a portion of the combustible nozzle gas stream is passed into the heat shield and over the fastener at a velocity at least as great as the flame propagating velocity. In one embodiment, the gutter is segmented to facilitate removal through a smaller nozzle opening. Alignment pins between adjacent gutter segments provide proper gutter segment orientation, while adjacent segments are attached together through cooperating flanges on the upstream surfaces of the segments to minimize flow blockage pressure losses.

Abstract: A valve for controlling the fluid flow between two generally coannular ducts. The valve is provided with a pair of back-to-back, mutually facing flow mixers of the daisy variety, each associated with a section of the coannular ducts. Each mixer transists the two coannular duct passages into a plurality of circumferentially separated chute passages communicating alternatively with the inner and outer ducts, the mixers being indexed with respect to each other by half a chute width. A stage of radially extending, pivotable vanes cooperates with the chutes of both mixers and allows both the inner and outer upstream duct flows to be directed to either the inner or outer downstream duct, depending upon the orientation of the vanes. Alternatively, either or both of the fluid streams can be blocked off entirely. Complete flexibility for flow inversion is obtained without turning or indexing the flow through the vanes by more than half a chute width, thereby maintaining high efficiency.

Abstract: A method and apparatus for measuring deflection of rotating members, such as the blades of a turbomachinery stage, are provided. The rotating member is illuminated with a high intensity light beam, such as a laser, at least one location upon the member where deflection is to be determined. Another location which serves as a reference is also illuminated in a similar manner. As the rotating member passes through the light beams, the light beams are reflected from reflective patches, thereby producing light impulses which are received by a light measuring device. The light pulses are converted to electrical impulses, the time increment between pulses being a function of the distance between the two locations and, thus, a measure of deflection. The dynamic component of blade-to-blade vibration is determined by comparing the time increments for a plurality of blades in the stage.

Abstract: A propulsion nozzle having a substantially cylindrical translatable shroud partially defining an outer flow duct and an articulated plug mounted within the shroud to partially define an inner coannular flow duct. A variable position valve comprises the downstream portion of the common wall between the ducts for modulating the relative flow rates between ducts and for creating a favorable static pressure balance therebetween. The shroud and plug cooperate to form a variable area throat for the combined duct flows.

Abstract: An article such as a blade fabricated from a plurality of high-strength, reinforcing filaments embedded in a matrix material and characterized by a portion of the filaments oriented transverse to the blade longitudinal axis in a direction through the blade to enhance transverse shear strength. In one embodiment, a plurality of columnar filament cores are each wrapped with a filament sheet and bonded together laterally to form the blade primary structure. The orientation of the filaments within the sheet forms an angle with the core longitudinal axes such that at least a portion of the sheet filaments runs transverse to the blade from one aerodynamic surface to the other. In an alternative embodiment, a blade is formed of a plurality of bonded filament laminates accordian folded with the fold lines angled with respect to the longitudinal axes of the filaments, the distance between fold lines being equal to or greater than the blade thickness.

Abstract: A sound-attenuating inlet duct is provided for a gas turbine engine wherein the inlet duct includes a casing defining, in serial flow relationship, a minimum area throat of predetermined axial extent, a diffuser and a cylindrical section. Sound-absorbent acoustic material is disposed upon the inner walls of the duct in the cylindrical section. A first amount of acoustic attenuation is provided by accelerating the motive fluid to high subsonic velocities through the throat. A second amount of acoustic attenuation is provided by locally accelerating the motive fluid in the vicinity of the acoustic material, thereby imparting a velocity component to the acoustic waves which is normal to the acoustic material, thereby enhancing absorption. By sizing the various sections of the inlet duct in a unique predetermined relationship the effects of the two sources of acoustic attenuation may be made additive.

Abstract: A rotor apparatus comprising a blade having a root adapted to swing laterally within a supporting spindle under impact loading is provided with a flow path defining platform. The platform comprises an inner shroud extending generally laterally of the blade airfoil portion and adapted to swing laterally therewith. In one embodiment wherein the blade primarily comprises a laminate of composite filament plies, the inner shroud is bonded to the laminate. An outer shroud, fixed with respect to the supporting spindle, forms a lateral extension of the inner shroud with the blade in its normal operating position. The inner and outer shrouds are provided with a pair of complementary adjacent surfaces contoured to pass in relatively close-fitting relationship to each other when the blade swings under impact loadings.

Abstract: A gas turbine engine actuation system for simultaneously controlling the flow areas defined by two generally coannular ducts, each duct terminating in a nozzle of the variable flap variety. A bell crank pivotable about an axis on the outer (secondary) nozzle is link-connected to the inner (primary) nozzle and also to a translatable actuation ring. The geometry of the flaps, link and bell crank is such that when the secondary nozzle is positioned by the ring and bell crank, the movement thereof is transferred to the primary nozzle to modulate the throat areas defined thereby. Where the secondary (supersonic) nozzle is of the divergent variety extending downstream of the primary nozzle so as to provide a common expansion surface and exit area, a link connection between one of the secondary nozzle flaps and the actuation ring causes simultaneous exit area and throat area modulation in a predetermined relationship.

Abstract: A method of making a composite article having at least a minimum selected impact strength by first obtaining the impact energy absorption/shear strength relationship for the collimated filaments and matrix material comprising the article. Impact strength is improved by the selection of the relative bond strengths between constituents and the orientation of selected matrix materials relative to the impact surface of the article.

Abstract: A propulsion nozzle having a substantially axial nozzle shroud and an articulated plug mounted in spacial relation therewith to form a motive fluid flow path having a throat therebetween. The plug is articulative to permit the throat of the nozzle to be disposed, as required, in a position at the downstream end of the shroud or at a position upstream of the downstream end without translating either the shroud or the plug.

Abstract: An auxiliary fan is disposed upon the periphery of at least a portion of the fan of a conventional gas turbofan engine. Flow modulating components such as variable vanes and nozzles are utilized in conjunction therewith to produce a wide range of operating bypass ratios. Such an engine is one of the variable cycle variety and has the capability of operating efficiently at both subsonic and supersonic speeds.

Abstract: A gas turbine engine fuel delivery and control system is provided with means to recirculate all fuel in excess of fuel control requirements back to the aircraft fuel tank, thereby increasing the fuel pump heat sink and decreasing the pump temperature rise without the addition of valving other than that normally employed. A fuel/oil heat exchanger and associated circuitry is provided to maintain the hot engine oil in heat exchange relationship with the cool engine fuel. Where anti-icing of the fuel filter is required, means are provided to maintain the fuel temperature entering the filter at or above a minimum level to prevent freezing thereof. In one embodiment, a divider valve is provided to take all excess fuel from either upstream or downstream of the fuel filter and route it back to the tanks, the ratio of upstream to downstream extraction being a function of fuel pump discharge pressure.

Abstract: The composite filament laminates of a composite blade are splayed at the root thereof to receive metallic inserts therebetween. A transition material having a modulus of elasticity greater than that of the inserts and less than that of the laminates is bonded therebetween to more uniformly distribute the blade loadings into the root region.

Abstract: A propulsion nozzle having a substantially cylindrical translatable shroud partially defining an outer flow duct and an articulated plug mounted within the shroud to partially define an inner coannular flow duct. A variable position valve comprises the downstream portion of the common wall between the ducts. The valve cooperates with the shroud and the plug, as required, to form a variable area throat for either flow duct, or both.