Abstract: An exhaust duct for a turbofan aircraft engine includes a bulbous inner cone which blocks direct sight of the turbine through the duct. Ram air from the fan is caught by scoops and conveyed from a plenum into the double outer wall of the exhaust duct and through hollow struts to the inner cone. Circumferential outlets for film cooling air are distributed axially of the surface of the outer and inner walls. Also, film cooling air is discharged from the struts to cool the rear part of the struts which are visible from without the engine. Direct radiation from within the cone to the outside is blocked by ribs extending into the inside of the inner cone immediately upstream of the cooling air outlets.

Abstract: A system for controlling pressure of a fluid, specifically the pressure of servo oil delivered to a clutch which determines the torque transmitted by the clutch. The system includes a pump, a pressure regulating valve to provide servo oil at constant pressure from the pump, and a pilot valve controlled by a solenoid responsive to electric current to vary the pressure in a pilot fluid line supplied from the constant pressure line. The oil is delivered from the fixed pressure line to the clutch by a throttling flow control servo valve which can open for rapid filling of the clutch cylinder. This valve is biased to close by the delivered pressure and biased to open by the pilot pressure. It may also be biased to close by a spring, and in this case be restrained from completely closing, so that the valve assumes its minimum area when the delivered pressure is slightly less than the pilot pressure.

Abstract: A control system for a helicopter power plant with three power units driving the lifting rotor system. Each power unit comprises a gas-coupled gas turbine engine, a hydromechanical fuel control receiving electrical inputs to set a gas generator governor, an engine electronic control, and engine accessories.Power plant operation is normally controlled by the pilot through condition levers and switches on a control quadrant, through a collective pitch control for the rotor blades, and through a master beeper switch which is operable to trim the setting of a rotor speed governor and the gas generator governors. A condition lever transmits a speed command signal through the electronic control of each power unit to its gas generator governor. A collective pitch signal from the rotor control system is another factor in setting the gas generator governor of each unit.The power plant includes a power management control which equalizes the power outputs of the engines and includes the rotor isochronous governor.

Abstract: A cooling arrangement for high temperature turbines, particularly the first stage nozzles of gas turbine engines. Cooling is effected by compressor discharge air taken from the combustion chamber jacket of the engine. The shrouds of the nozzle have a base ring and a porous facing spaced from the base ring and exposed to the motive fluid. Cooling air fed through openings in the base ring flows through the porous facing into the motive fluid path to cool the facing by transpiration. The vanes are cooled by an arrangement providing for a mixture of impingement and transpiration cooling. Compressor discharge air is admitted between a baffle in the interior of the hollow vane and the high pressure face of the vane. Some of the air flows through the porous high pressure face for transpiration cooling. The rest of the air is discharged through a row of openings in the baffle to impinge on and cool the interior of the leading edge of the vane, which is imperforate.

Abstract: A combustion liner for a gas turbine combustion apparatus has a wall of circular cross-section defining a primary air entrance at its upstream end, providing means for introduction of fuel near the upstream end, having a convergent-divergent fuel prevaporization zone, a reaction zone, and a dilution zone.The primary air entrance has two coaxial entrance portions separated by an annular intermediate wall disposed around a centerbody. Swirlers in the two entrance portions swirl the air with different degrees of swirl, which provides shear between the two layers downstream of the swirlers. Fuel is introduced onto the intermediate or outer wall, or both, upstream of the throat. Air is admitted through the centerbody and directed towards the throat at higher fuel flow rates, but is shut off by a valve plug at low fuel flow rates to promote recirculation and thus improve flame stability under such conditions. The valve responds to fuel and combustion air pressure.

Abstract: A combustion method and apparatus for gas turbine engines employs a combustion process and combustion liner structure adapted to promote complete combustion of liquid hydrocarbon fuel and minimize undesired combustion products. Compressed primary air flows radially inward into a prechamber into which fuel is sprayed. Except during start-up, the air is heated. Normally, the air mixes with and evaporates the fuel and the mixture flows through a throat into a reaction chamber. The upstream end of the reaction chamber is bounded by a biconical annular wall, the inner radial portion of which diverges sharply and the outer radial portion of which diverges less sharply. The liner wall downstream of the throat defines the reaction zone and a dilution zone to which secondary air is admitted. The areas of both the primary and the secondary air entrances are variable to maintain a lean fuel-air ratio in the reaction zone throughout the operating regime.The swirl angle of the entering primary air is variable.

Abstract: A hydraulic position servo system includes a primary control valve moved by a mechanical input which embodies a pintle laterally shiftable in a cylinder to differentially throttle two orifices to establish a variable control pressure.

Abstract: A fluid dynamic machine has a single rotor providing the rotor portion of a centrifugal compressor and also the rotor portion of an axial-to-radial flow fan. The portion of the rotor blades adjacent the hub define a compressor blading and the axially forward part of each blade is extended outwardly to provide a fan blade. These are supplied from a common inlet eye, and the flow is split at the downstream side of the fan between the fan and compressor passages by a generally radial plate curving forwardly at its inner margin and providing the forward fixed shroud for the compressor blades. The fan diffuser is split in a generally diametrical direction.

Abstract: A control system for a gas-coupled gas turbine engine particularly directed to control of the setting angle of the power turbine nozzle of the engine and to correlation of the power turbine nozzle setting with fuel supply and with operating parameters of the engine. The control provides for operation of the engine from closed to full open throttle, with closed throttle calling for idle speed of the engine. The initial stage of opening the throttle develops an increasing nozzle reference temperature signal which is matched with a turbine temperature signal to control a servo which varies the setting, and therefore area, of the turbine nozzle. After the initial stage of throttle opening, the reference temperature signal increases with engine speed, which increases in response to an increasing throttle signal. The actual level of the nozzle reference temperature is also a function of engine inlet temperature up to a given level of this temperature.

Abstract: A turbine blade having a porous hollow sheet metal airfoil and a base defining a platform, stalk, and root. The airfoil portion is integral with an extension which lies within the blade stalk, the base being cast around this extension. The cast metal lies around the blade wall and also through tubes welded from wall to wall of the extension. The stalk also includes an opening to admit air to the interior of the blade for transpiration through the blade wall.

Abstract: A labyrinth seal has two relatively rotatable members which are configured to define between them a succession of annular orifice or clearances between seal knives on one member and generally cylindrical surfaces or lands on the other. The members define a doubly recurved flow path from each orifice to the orifice next downstream. The first reversal of flow is effected by a barrier at the downstream end of the land having a hemi-toroidal surface to deflect the flow back toward the orifice. Flow is again reversed in passing around the barrier and flows between the barrier and the other seal member to the next downstream orifice. A ring of slots through the barrier tangential to the hemi-toroidal surface discharges some of the flow into the twice reversed flow so as to provide an aerodynamic dam to increase turbulence and reduce the flow area and, therefore, increase pressure drop and sealing effectiveness.

Abstract: A control system for a helicopter power plant with three power units driving the lifting rotor system through a main gearbox. Each power unit comprises a gas turbine engine of the gas-coupled type, a hydromechanical fuel control receiving electrical inputs to set a gas generator governor in the fuel control, an engine electronic control, and various engine accessories.The operation of the power plant is normally controlled by the pilot through condition levers and switches on a control quadrant, through a pitch control by which the collective pitch of the rotor blades is controlled, and through a master beeper switch which is operable to trim the setting of an isochronous governor for the rotor system and the gas generator governors. The condition lever of each engine transmits a speed command signal through the electronic control of each power unit to its gas generator governor.

Abstract: A control system for a gas-coupled gas turbine engine particularly directed to control of the setting angle of the power turbine nozzle of the engine and to correlation of the power turbine nozzle setting with fuel supply and with operating parameters of the engine. The control provides for operation of the engine from closed to full open throttle, with closed throttle calling for idle speed of the engine. The initial stage of opening the throttle develops an increasing nozzle reference temperature signal which is matched with a turbine temperature signal to control a servo which varies the setting, and therefore area, of the turbine nozzle. After the initial stage of throttle opening, the reference temperature signal increases with engine speed, which increases in response to an increasing throttle signal. The actual level of the nozzle reference temperature is also a function of engine inlet temperature up to a given level of this temperature.

Abstract: A combustion liner for a gas turbine combustion apparatus has a wall of circular cross-section defining a primary air entrance at its upstream end, providing means for introduction of fuel near the upstream end, having a convergent-divergent fuel prevaporization zone, a reaction zone, and a dilution zone.The primary air entrance has two coaxial entrance portions separated by an annular intermediate wall disposed around a centerbody. Swirlers in the two entrance portions swirl the air with different degrees of swirl, which provides shear between the two layers downstream of the swirlers. Fuel is introduced onto the intermediate or outer wall, or both, upstream of the throat. Air is admitted through the centerbody and directed towards the throat at higher fuel flow rates, but is shut off by a valve plug at low fuel flow rates to promote recirculation and thus improve flame stability under such conditions. The valve responds to fuel and combustion air pressure.

Abstract: A simple by-pass type jet propulsion engine includes a centrifugal compressor and a centripetal turbine mounted back-to-back and a combustion apparatus disposed radially outwardly of the turbine. These constitute the core engine; the fan part of the engine is provided by fan blades extending outwardly from the rotor blades of the core engine compressor which discharge through outlet guide vanes into a fan duct lying radially outwardly of the combustion apparatus. The fan outlet guide vanes or the fan duct nozzle may be variable to substantially close the fan duct for starting the engine. Part of the air flows from the compressor to the combustion apparatus of the core engine through hollow turbine nozzle vanes.

Abstract: A diffuser for a radial-flow compressor with a circumferentially and radially extending annular splitter plate dividing the entrance portion of each diffusing passage into two parallel passages.

Abstract: A combustion liner for a gas turbine combustion apparatus has a wall of ceramic material. To minimize destructive thermal gradients in the ceramic material due to local cooling by air entering the liner through ports for combustion or dilution air, the walls of these ports are isolated from the entering air by metal bushings inserted through each port, these bushings being retained by a band encircling the liner and connected to the bushings.

Abstract: A porous seal element usable as a blade tip seal in a turbomachine or as an element of a labyrinth seal is made up of a large number of strips disposed edgewise to the sealing face of the element and extending in the direction of relative movement of the seal elements. The strips have grooves extending across the strip for discharge of a cooling fluid such as air. The presence of the grooves provides a low density structure at the seal face of the seal element which may be abraded if there is rubbing contact and provides for metering of coolant at the rear face of the seal element. The seal element is fabricated by etching sheets so each sheet defines a number of parallel strips joined by weak ties and with the grooves extending across the strips; stacking the sheets and bonding them together; and then separating the bonded structure at the weak ties so that each stack of strips defines a seal element.

Abstract: A combustion apparatus for gas turbine engines particularly adapted to reduce emissions to meet automotive requirements. The fuel is laid on the wall of a cylindrical prechamber and evaporated from the wall by combustion air which is introduced through a swirler at the upstream end of the prechamber. The inner surface of the prechamber is artificially roughened by a grid of grooves to improve fuel evaporation. The fuel is laid on the wall from an annular manifold extending around the upstream end of the prechamber through tangential orifices leading from the manifold into the interior of the prechamber. The fuel manifold is cooled and shielded from heat by an air jacket. More air enters through entrance ports distributed around the prechamber toward its downstream end. The resulting lean fuel-air mixture is delivered past an annular flow dam at the outlet of the prechamber into a combustion or reaction zone which is abruptly enlarged from the prechamber.

Abstract: A combustion liner suitable for an automotive gas turbine has variable primary and secondary air admission ports through the wall of the liner. The areas of these sets of ports are varied jointly by two annular valve sleeve assemblies reciprocable on the surface of the liner. Each valve sleeve assembly comprises an outer rigid ring, four approximately quarter-cylindrical valve plates extending around the outer surface of the liner within the ring and coupled to the ring for reciprocation by it, and a leaf spring disposed between the ring and each valve plate to hold the valve plate in contact with the liner.