Abstract: A protection system for use with a bleed manifold of a gas turbine engine is provided and is comprised of barrier means disposed within the manifold for preventing at least a portion of incendiary particles entrained in a fluid flowing instream through the manifold from impinging upon a wall associated with said manifold. Shielding means are also provided for shielding engine casing bleed ports from impingement by the particles.

Abstract: A gas turbine engine is provided with a long nacelle which forms both the inlet and exhaust of the engine. The nacelle is spaced apart from a core engine to define an annular bypass duct therebetween. The incoming air stream is pressurized by a front fan disposed in the inlet and then divided between the core engine and bypass duct. A lobed mixer device is provided downstream of the core engine to intermix the core engine and bypass duct exhaust streams. The mixed streams are discharged from a common nozzle formed at the downstream end of the nacelle. A non-redundant system of mounts are provided to secure the engine to the pylon of an aircraft in such a manner as to reduce engine thrust induced bending loads and insure symmetry of these thrust loads. The total reaction of the thrust loads at the mounting points is reduced by a unique interlocking system by which all of the major engine assemblies are joined.

Abstract: An improved back-up control for use in an aircraft gas turbine engine is presented and includes a fuel control valve adapted to meter the flow of fluid to the gas turbine engine, first means for providing a mechanical position signal indicative of the magnitude of a desired fuel flow change to the engine and second means for limiting the rate at which a change in the signal is transmitted to the fuel control valve thereby limiting the rate of change in fuel flow to the engine. The second means may limit the transmission rate in response to inlet pressure. A variable geometry control valve is provided for varying the position of the variable elements of the gas turbine engine in response to said mechanical position signal and the second means limits the rate at which a change in the signal is received by the variable geometry control valve.

Abstract: A digital system for producing a bipolar rectangular waveform of fixed frequency having a duty cycle proportional to the magnitude of an input digital word is provided to drive a servovalve. The digital word is input to a modulator which outputs a fixed frequency rectangular waveform whose duty cycle varies from 0 to 100% dependent upon the magnitude of the digital word. In order to adapt this output to drive a fail-fixed servovalve in which maximum flow occurs at a predetermined portion of maximum rated current, a scaling network is provided which limits the variation in the duty cycle of the output square wave.

Abstract: An integrated control system for use with a gas turbine engine is provided wherein the control system includes a fuel control valve adapted to meter the flow of fuel to the engine, variable geometry control valve to control compressor variable stators or bleed, back-up control means for providing signals to the control valves and primary control means for providing bias of the signals. Means are provided for biasing the signals during normal mode of operation and the means may be ineffective to bias the signals during failed mode of operation.

Abstract: A thrust control system is provided for varying the thrust output of a gas turbine engine. The system is adapted to control the thrust output of the engine in a first mode in accordance with at least a pair of thrust-indicating parameters. The system is further adapted to control thrust output of the engine in a second mode in accordance with one of the thrust-indicating parameters.

Abstract: An integrated history recorder for a gas turbine engine includes a number of integrally controlled displays which together provide a comprehensive record of accumulated engine life. The recorder is adapted to interface with an engine contained transducer assembly.Displays indicative of the following parameters are provided: the number of engine starts, engine running time, the number of engine turbine over-temperature occurrences, turbine time-temperature index, and a manually resettable flag which sets on occurrence of a turbine over-temperature event. These integrally controlled displays provide a comprehensive indication of the cumulative duty performed by the gas turbine engine.

Abstract: Hollow cylindrical metal structures with internal contours are constructed from a thick-walled hollow cylinder of axial length, weight and outside diameter substantially equal to the axial length, weight and outside diameter of the desired preform. The cylinder is placed in a restraining cylindrical container having an inside diameter and length substantially equal to the outside diameter and length respectively of the cylindrical structure. The entire assembly is then rolled between a forming roll die having a contoured outside face abutting the inside face of the hollow cylinder and a support roll die abutting the outside face of the container until the inside face of the hollow cylinder conforms to the profile of the forming roll. Radial growth of the hollow cylinder during this contouring operation is inihibited by the cylindrical container. Axial growth of the hollow cylinder during the contouring operation is also inhibited with the help of flanges on the roll dies.

Abstract: In a flow metering valve of the type in which flow through the outlet ports is regulated as a function of spool displacement and the measured pressure difference across the outlet port, valve accuracy is greatly improved by providing a ducted chamber through the valve casing to communicate with the valve interior such that upstream pressure at the outlet is measured internal to the valve. This arrangement prevents the hydraulic losses associated with the internals of the valve from generating erroneous pressure measurements.

Abstract: A combustor for use in a gas turbine engine is provided with a first wall defining a combustion zone; an outer casing partially defining a cooling plenum about the first wall; a second wall spaced apart from the first wall and defining together therewith a second plenum, the second wall bearing a plurality of perforations for passing fluid from the first plenum in impinging streams upon the first wall; and a plurality of ribs extending between the first and second walls and compartmentalizing the second plenum. The ribs add substantial stiffness to the combustor as well as providing for independently controlled cooling of the substantially isolated compartments formed thereby. The impinging streams provided by the perforations in the second wall substantially increase local fluid velocities and conductive heat transfer.

Abstract: A fuel delivery system is presented wherein first and second heat exchanger means are each adapted to provide the transfer of heat between the fuel and a second fluid such as lubricating oil associated with the gas turbine engine. Valve means are included which are operative in a first mode to provide for flow of the second fluid through both first and second heat exchanger means and further operative in a second mode for bypassing the second fluid around the second heat exchanger means.

Abstract: An acoustic duct such as a jet engine fan duct is lined with a plurality of circumferentially spaced strips of sound-absorbing materials which extend helically about the duct axis and which are effective to scatter spinning mode acoustic pressure fields to higher order attenuating modes for improved noise suppression. To maximize noise reduction, the pitch angle of the helix may be aligned to the direction of the wave front generated by the first stage rotor blades of a fan or compressor disposed in the duct when operating at a supersonic velocity relative to the incoming airstream. Alternate strips may be tuned to different frequencies and/or be separated by untreated strips.

Abstract: A design technique, method and apparatus for containing failure of the rotors of axial flow fluid machines. A rotor disk is constructed of at least three disk sections. Each disk section is shaped such that the loading on that section will be distributed in an optimum manner from the rim to the hub of the disk. To prevent crack propagation from one disk section to another, and to minimize structural weaknesses in the disk sections, the live disk sections are bolted together in a single bolt circle. In order to reduce overall disk weight while maintaining a maximum level of failure containment, the inner disc sections are made thicker than the outer disk sections. Embodiments for the fan, compressor and turbine rotor sections of a gas turbine engine are disclosed.

Abstract: Airflow exiting a centrifugal compressor is diffused in multiple shaped passages tangential to the compressor impeller dumped into a plenum to reduce its Mach number and then directed through deswirl vanes to the entrance of a combustor. Deswirl at reduced Mach number significantly reduces pressure losses resulting in reduced complexity and manufacturing cost for the diffuser deswirl system.

Abstract: A method is provided for manufacturing a concentric-tube heat exchanger which includes at least a pair of concentric tubes disposed one within the other to form an annular longitudinally extending flow channel in which a plurality of heat transfer promoting fins reside. The method includes the step of applying a radially directed force to one of the pair of concentric tubes in sufficient magnitude to permanently deform the tube into engagement with the plurality of heat transfer promoting fins.

Abstract: A concentric-tube heat exchanger is provided which includes a first longitudinally extending annular flow passage adapted to provide a flow path for a first fluid flowing therein and a first plurality of annular heat transferring plates disposed consecutively in the axial direction in the annular flow passage. The plates extend radially across the annular passage and each have a first set of apertures extending axially through the plate. First means are provided for at least partially defining a second longitudinally extending flow passage for a second fluid. The second flow passage is disposed concentrically with the first annular flow passage and is in sufficient proximity thereto to permit a transfer of heat between the first and second fluids through said first plates in the radial direction.

Abstract: Gas turbine engine blades and single-die cavities are dynamically balanced on a rotor, transferred to a neutral atmosphere heated chamber and rotated. The centrifugal force distributes sufficient stress on both the blade's platform and airfoil to correct critical geometrical characteristics by creep forming in a relatively short time. The process is not affected by the blade surface irregularities, which cause die damage in conventional opposed-die forming due to high stress concentrations.

Abstract: An interstage spacer for the turbine section of a gas turbine engine is provided with a flexible bellows which absorbs axial growth of the adjacent turbine stages to prevent seizing and binding.

Abstract: A deformable bearing seat is provided for seating a bearing assembly in a housing. The seat includes a seating surface in the housing having a first predetermined contour when the housing is in an undeformed mode. The seating surface is deformable to a deformed contour when the housing is in a deformed mode. The seat is particularly adaptable for application to a rotating blade and mounting ring assembly in a gas turbine engine.

Abstract: The inlet of a gas turbine is provided with a mechanism for varying the throat area which may be selectively adjusted to maintain the velocity of an incoming air stream at a high level during aircraft takeoff and climbout to thereby reduce forward propagated noise.