Abstract: A fan duct flow control method and apparatus is provided for controlling fan bypass airflow at an inlet into an exhaust duct cooling annulus of a variable cycle gas turbine engine. The flow control employs a translating ring as a valve-like device that interacts with an annular lip on an inlet into the exhaust duct cooling annulus. The translating ring is positioned to restrict airflow into the liner during appropriate periods in engine operation. This flow control is uniquely constructed to be conveniently operated by a variable cycle engine actuation system that injects fan bypass air into an engine exhaust duct. The method and apparatus in one form is also used to block fan duct flow and reduce forward thrust during aircraft taxi operations.

Abstract: A nonaxisymmetric, variable area, exhaust nozzle is provided with thrust vectoring capabilities in one plane. The nozzle incorporates an upper, thrust vectoring flap to control direction of thrust over various flight conditions, and a lower, area control flap that is pivoted to modify size and location of the nozzle throat. The structural aspects of this nozzle provide a unique capability to vector thrust up to 60 degrees while changing the nozzle throat position to a region downstream of the vectoring of the exhaust gases.

Abstract: Apparatus is provided for maintaining minimum clearance between variable position airfoils and the wall forming the gas flow path in a gas turbine engine. A constant clearance is maintained between a radially facing contoured wall surface and a radially facing contoured end face on the airfoil. The contour of the wall surface and the end face may each be spherical.

Abstract: Apparatus for releasably clamping a plurality of elements, such as electrodes associated with an electrical machine, are provided wherein a housing generally defines a cavity with at least one of the elements protruding into the cavity. A fluid medium adapted for hydrostatic pressurization is disposed within the cavity and means are provided which are also disposed within the cavity and responsive to hydrostatic pressurization of the medium for generating a force for clamping the element.

Abstract: A diffuser is provided for achieving efficient conversion of the dynamic head associated with pressurized fluid into static pressure. The diffuser includes structure for reducing the boundary layer accumulated by the fluid during flow in the diffuser and for turning the fluid within the diffuser flowpath.

Abstract: An improved flexible coupling for use in conjunction with a flexible high speed coupling shaft includes means for increasing the coupling axial stiffness while maintaining a high degree of alignment offset capability and the same overall shaft axial stiffness.

Abstract: A system of separating or removing foreign particles from the gaseous fluid flowing in the primary flow path of a gas turbine engine is provided wherein the particles are removed from the stream near the engine inlet and flow through a conduit to ejector means operative to effect a flow of a second stream of fluid in the conduit. Mixing means are provided for mixing the second stream of fluid with the gaseous fluid flowing in the primary flow path.

Abstract: An apparatus is provided to supply oil to a differential bearing mounted between relatively rotating concentric shafts, for example, inside a gas turbine engine. In one form, the apparatus includes a fixed nozzle that injects oil into an annular collector dam mounted on the outer floating shaft. The dam construction utilizes centrifugal force to cause the oil to flow forward through passages into an interior area of the outer shaft. Inside such shaft, the oil is directed by dispensers into an oil transfer tube that traverses the distance inside the shaft from the dispensers to the bearing. The inside wall of the tube is flared to a larger diameter at the forward end, and the centrifugal force resulting from shaft rotation forces the oil forward into the bearing. At the forward end, the transfer tube contacts the outer race of the bearing thereby lubricating the bearing throughout a 360 degree surface area.

Abstract: A seal and method for making same is provided for use in a gas turbine engine. The seal includes a composite article having a substrate of sintered metallic fibers with an apparent density within the range of 14.0% to 22.5%. The substrate comprises a network of interconnected pores and metallic bonds at points of contact between fibers. The substrate further includes an external face having surface pores communicating with the network of pores. A thin film barrier surface layer, impervious to the passage of fluid, is disposed on the external face of the substrate and fills the surface pores.

Abstract: A pair of turbofan engines are cross connected such that during normal-mode operation horsepower can be shared by the respective cores, and when one engine core becomes inoperative the fan of that engine can be driven by the turbine of the operative engine to thereby maintain a substantial thrust output. In order to balance the respective thrust outputs, variable inlet guide vanes are controlled to decrease the fan mass flow in the operative engine and increase the fan mass flow in the inoperative engine. The variable inlet guide vanes are so constructed as to only partially span the fan duct so as to not appreciably affect the airflow to the core when the inlet guide vane angle setting is altered to allow the core to thereby retain a high level of supercharging during this operational period of maximum power demand.

Abstract: An air-to-air heat exchanger is provided for a gas turbofan engine to significantly reduce the quantity of cooling air that is presently needed to effectively cool the hot turbine parts. Typically, the turbine is internally cooled with air bled from the compressor which, though cooler than the turbine, has been heated due to the work done on it by the compressor. In accordance with the present invention, the heat exchanger is located internally of the bypass duct to place in heat exchange relationship a captured portion of the relatively cool bypass flow and this warmer compressor bleed air, thereby cooling the turbine coolant and significantly reducing the amount of such coolant required. This results in a decrease in engine specific fuel consumption.

Abstract: A gas turbine engine comprising a fan, a compressor and a turbine, wherein the torque requirements of the fan or compressor can be modulated, is provided with differential gearing to transmit all of the fan and compressor power requirements from the turbine. The differential gearing maintains an adjustable speed relationship between the fan and compressor with respect to the turbine depending upon the torque requirements thereof and the gear ratios within the differential gearing.

Abstract: An apparatus is provided in a gas turbine engine for eliminating air leakage-induced vibration at natural frequencies in a type of flexible annular seal structure sometimes referred to as a floating fishmouth seal. A floating fishmouth seal has male and female sections arranged to permit axial and radial movement and still maintain a sealing relationship. In a preferred form, the apparatus for eliminating air leakage-induced vibration includes two structures that interact with the male and female sections of the fishmouth seal during engine operation. The first structure is an annular leaf spring assembly that presses a radial flange of the male section of the seal against a stationary wall to obtain frictional damping. The second structure is an annular member attached to an outer surface of the female section of the seal forming a closed-in structure to provide stability and damping. The combined effect of the two structures is to increase the operational life of the fishmouth seal.

Abstract: A propulsion system for use primarily in V/STOL aircraft is provided with a variable cycle, double bypass gas turbofan engine and a remote augmenter to produce auxiliary lift. The fan is oversized in air-pumping capability with respect to the cruise flight requirements of the remainder of the engine and a variable area, low pressure turbine is capable of supplying varying amounts of rotational energy to the oversized fan, thereby modulating its speed and pumping capability. During powered lift flight, the variable cycle engine is operated in the single bypass mode with the oversized fan at its maximum pumping capability. In this mode, substantially all of the bypass flow is routed as an auxiliary airstream to the remote augmenter where it is mixed with fuel, burned and exhausted through a vectorable nozzle to produce thrust for lifting.

Abstract: An inlet for a gas turbine engine is disposed about a curved centerline for the purpose of accepting intake air that is flowing at an angle to engine centerline and progressively turning that intake airflow along a curved path into alignment with the engine. This curved inlet is intended for use in under-the-wing locations and similar regions where airflow direction is altered by aerodynamic characteristics of the airplane. By curving the inlet, aerodynamic loss and acoustic generation and emission are decreased.

Abstract: An integrally cast structural cooling air manifold for a gas turbine engine being of generally annular shape and having two concentric thin walls defining a plenum therebetween. Each of the walls is provided with embossments through which aligned radial holes are bored to furnish support for a stage of rotatable vane trunnions. A series of circumferentially spaced inlet ports on the outer wall distribute cooling air into the plenum, from which it is routed to the vane airfoil portions to perform cooling functions by means of passages which commumnicate with the plenum via openings in the vane trunnions. Thus, the manifold performs the dual functions of distributing coolant to the vanes and supporting the vane trunnions in the manner of a turbine frame.

Abstract: A turbine assembly is provided by which a variable area turbine vane may be cantilever mounted from an outer structural frame and further supported by an inner structural frame. The vane includes an inner trunnion about which is installed an inner band sector to partially define a flow path through the turbine. The band sector is provided with a hole which receives the trunnion. Once the vane is cantilevered from the outer frame and the band sector installed, an inner annular frame is slid under the vane trunnion to align a hole in the frame with the trunnion. A generally cylindrical trunnion extension is inserted through the frame hole and over the end of the trunnion, and then attached to the trunnion through a bolted connection. The extension is journaled for rotation within the inner structural frame hole. Passageways are provided to route cooling air from the vane into the structural frame to provide cooling of the band sector.

Abstract: An improved bearing assembly is provided for supporting a rotating shaft. The improvement is comprised of utilizing a resilient support means in combination with a multiple squeeze film damper apparatus. The damper apparatus provides a large damping force to suppress large vibrations and excessive radial shaft deflections in the event of operation with an abnormally high unbalanced shaft. The resilient support provides a soft spring system as a means for establishing and maintaining the critical rotor speed at a low speed condition, for centering the shaft during normal operation, and for allowing radial deflection during operation with an unbalanced shaft.

Abstract: An improved blade retainer for locking radially projecting blades on a rotor includes an elastic spacer sized to be inserted into a radial space between the blade tang and the bottom of the rotor slot in a generally undeformed state without deformation of the tang or slot. The spacer is provided with a first arcuate surface which abuts the tang and a second arcuate surface which, in one embodiment, abuts the bottom of the rotor slot when the spacer is deformed, thereby exerting an outwardly directed load on the tang. The spacer is fixed against axial movement relative to the blades by means of a forward end lug which is in confronting and overlapping relationship with an end face on the blade tang when the spacer is deformed. Blocker means are insertable between the spacer and the bottom of the slot to retain the spacer in a deformed state and thereby bias the blade radially outwardly.

Abstract: A gas turbine engine comprising a number of annular wall sectors which form a complete circular wall defining a hot gas passage is provided with a cooling system incorporating a plurality of hollow impingement vessels disposed in a circular array within an annular chamber behind the wall. Cooling fluid is routed to the self-contained impingement pressure vessels which are provided with perforations to disperse the cooling fluid into impingement upon the wall. Unlike prior systems, the impingement vessels are not physically attached to the band but, rather, are supported by a structural frame which partially defines the annular chamber and, in the preferred embodiment, also supports the wall sectors. Since the impingement vessel, and not the backside of the wall, is the pressure vessel for the pressurized cooling fluid, leakage between adjacent wall sectors is greatly reduced with no loss in cooling effectiveness when compared to conventional cooling systems. Thus, turbine cycle performance is improved.