Abstract: A small gas turbine engine, such as is used to power a UAV, that includes at least one centrifugal compressor having an impeller with blades that form a gap between the blade tips and stationary shroud of the gas turbine engine, and where a resistance heating element, such as an impingement air manifold, is secured to or bonded to a compressor casing of the gas turbine engine in order to use heat to control the gap between the impeller blades and the stationary shroud. The resistance heating element is activated at cruise mode to move the shroud toward the impeller. Additionally or alternatively, the compressor casing is heated with bled-off compressed air to move the shroud toward the impeller. A capacitance tip clearance sensor can be mounted on the impeller shroud to monitor and control tip clearance in real time.

Abstract: A two-dimensional variable area plug (2D VAP) nozzle assembly for a high-speed flight vehicle. In one embodiment, a 2D VAP nozzle assembly comprises a nozzle including a plurality of sidewalls; a plug body within the nozzle, the plug body abutting at least two of the plurality of sidewalls; a first convergent flap hingedly connected to at least one of the plurality of sidewalls; and a second convergent flap hingedly connected to at least one of the plurality of sidewalls. In one embodiment, the nozzle assembly includes only a first convergent flap and a second convergent flap, without diverging flaps. The 2D VAP nozzle assembly has a simplified design with reduced sidewall length, which results in reduced manufacturing and maintenance costs.

Abstract: An aero vehicle with a dual mode propulsion system that can operate in a first mode below a ramjet speed and a second mode at a ramjet speed. The first mode is operated using a compressor driven by an electric motor supplied with electrical power from a power pack. When the vehicle has reached a speed where the ramjet engine can operate, the power pack is dropped from the vehicle to decrease the weight of the vehicle.

Abstract: A geared turbofan engine with at least one compression stage and at least one turbine stage on a high speed shaft, the high speed shaft coupled through a speed reduction gear box to a low speed shaft with a fan and a starter/generator. The low speed shaft is collinear with the high speed shaft but does not rotate within the high speed shaft. The speed reduction gear box is positioned between and mechanically couples the high speed shaft and the low speed shaft, which allows the fan and the integrated starter/generator on the low speed shaft to operate at a lower speed than the high speed shaft.

Abstract: A lay shaft assembly for a speed reduction gearbox in a geared turbofan gas turbine engine, the lay shaft assembly having an output gear formed on a lay shaft as a single piece, and an input welded gear formed as a separate piece that is welded to the shaft in close proximity to the output gear. The output gear is machined and precision-ground prior to welding the input welded gear to the lay shaft so that the two gears can be located in close proximity. The input welded gear is precision-ground after the gear has been welded to the shaft.

Abstract: A small gas turbine engine, such as is used to power a UAV, that includes at least one centrifugal compressor having an impeller with blades that form a gap between the blade tips and stationary shroud of the gas turbine engine, and where a resistance heating element is secured to or bonded to a compressor casing of the gas turbine engine in order to use heat to control the gap between the impeller blades and the stationary shroud. The resistance heating element is activated at cruise mode to move the shroud toward the impeller. Additionally or alternatively, the compressor casing is heated with bled-off compressed air to move the shroud toward the impeller. A capacitance tip clearance sensor can be mounted on the impeller shroud to monitor and control tip clearance in real time.

Abstract: An apparatus, system, and process for testing a gas turbine engine or other test object under a cold condition, such as a compressor of a gas turbine engine, a combustor of a gas turbine engine, or an afterburner of an aero gas turbine engine, using compressed air stored in an underground storage reservoir of a CAES system along with an air turbine or an air injector. High-pressure, but low-volume, compressed air from a CAES system can be converted into a low-pressure, but high-volume, flow of compressed air using an air injector to supply enough compressed air to test a combustor or an afterburner. High pressure compressed air from the CAES system can be used to drive an air turbine that then drives a compressor for testing.

Abstract: A gas turbine engine in which a long length-to-diameter (L/D) flexible shaft is used to connect two high speed shafts in order to tolerate misalignment. In order to reduce the overall system length, a smaller diameter flexible shaft is contained within but not in contact with a larger diameter primary turbomachinery shaft such that the smaller flexible shaft adjoins to the primary shaft aft of the primary shaft bearing. This design reduces a length of the overall system and reduces additional cost associated with a flex bellows or spline.

Abstract: A gas turbine engine with a bearing that is supplied with fuel and compressed air for both cooling and lubrication of the bearing. The bearing housing contains a serpentine flow cooling circuit with each leg formed from a plurality of parallel flow channels, and where fuel is supplied to the cooling circuit and then discharged into a combustor. Some of the fuel is also bled off and passed into the bearing compartment along with compressed air bled off from the compressor to both cool and lubricate the bearing.

Abstract: A process for forming a metal part from an additive manufacturing process with a smooth surface that includes the steps of printing the part using an AM process, heating the printed part to its solution heat treat or annealing temperature, placing the printed part in a fluidized salt bath for a short period of time to smooth a rough surface on the metal part, and then rapidly cool the heated metal part to prevent any change in grain structure. If the metal part is made from a metal material that oxidizes, then the metal part is treated in an enclosed chamber with Argon gas.

Abstract: A process for retrofitting an industrial gas turbine engine of a power plant where an old industrial engine with a high spool has a new low spool with a low pressure turbine that drives a low pressure compressor using exhaust gas from the high pressure turbine, and where the new low pressure compressor delivers compressed air through a new compressed air line to the high pressure compressor through a new inlet added to the high pressure compressor. The old electric generator is replaced with a new generator having around twice the electrical power production. One or more stages of vanes and blades are removed from the high pressure compressor to optimally match a pressure ratio split. Closed loop cooling of one or more new stages of vanes and blades in the high pressure turbine is added and the spent cooling air is discharged into the combustor.

Abstract: A small gas turbine engine with a ceramic turbine to allow for higher turbine inlet temperatures, where a metallic compressor is secured to a ceramic shaft extending from a ceramic turbine to form a single piece ceramic shaft and turbine, where a threaded nut secures a split ring retainer on the compressor end of the ceramic shaft. A hollow thrust runner is compressed between the compressor disk and the turbine disk by the threaded nut to secure rotor together. A centering spring forms a tight fit between the metallic thrust runner and the ceramic shaft on the turbine side.

Abstract: An air cooled integrally bladed rotor with single crystals turbine rotor blades having cooling air passages formed into an equiax rotor disk, where a mold having expendable Molybdenum tooling and reusable molybdenum tooling is used to form the IBR. An annular blade ring with openings is used to secure the single crystal rotor blades within the mold, and a number of tube tools are inserted into a bottom end of each blade that forms a cooling air supply passage within the rotor disk. Two molybdenum circular shaped hubs are used to secure a bottom end of the tube tools with the mold. The mold is filled with metal powder and high pressure is used to solidify the powder to form the IBR. Expendable tooling is removed using sublimation when exposed to oxygen. Reusable tooling is reused to form additional IBRs.

Abstract: An air cooled integrally bladed rotor with bore entry cooling holes for a small gas turbine engine cast using a ceramic core having an axial bore forming piece with a plurality of radial extending spokes that end in an annular ring to form cooling air supply passages for air cooled turbine blades. Bulbous chambers are formed in a circumferential cooling air supply channel formed below each blade, where cooling air holes are drilled from a tip of each blade and into the bulbous chambers. The radial spokes have an elliptical cross sectional shape with a major axis perpendicular to a rotational axis of the central bore of the IBR. A spacing of the inlet openings in the bore are minimized to reduce stress.

Abstract: A gas turbine engine for an aircraft such as a UAV includes a compressor connected to a turbine with a combustor to produce a hot gas stream. The rotor is supported by two radial foil bearings. An axial thrust bearing assembly is positioned between the compressor disk and the turbine disk and includes an axial thrust bearing radial disk extending from a hollow axial tube. Compressed air is bled off from the compressor and passed into an axial thrust balance chamber to provide the axial thrust balance for the rotor. The compressed air from the thrust bearing chamber then flows through both of the radial foil bearings for cooling, is collected in and around the hollow tube, and then discharged into the inlet of the turbine. An orifice can be adjusted to meter and control a pressure occurring in the thrust balance chamber.

Abstract: A system and method for testing a combustor or other component of a large industrial gas turbine engine. A test facility for testing a gas turbine engine component includes a storage reservoir, a heat exchanger (13) with a first fluid flow passage connected to the storage reservoir and a second fluid flow passage, a combustor (18) connected to the second fluid flow passage of the heat exchanger (13), a hot gas stream from the combustor flowing within the second fluid flow passage, and a test component of a gas turbine engine connected to the second fluid flow passage of the heat exchanger (13). The compressed air from the storage reservoir (11) passes through the heat exchanger (13) first fluid flow passage and is preheated from the hot gas stream passing through the second fluid flow passage, and the preheated compressed air from the heat exchanger (13) passes into the test component for testing.

Abstract: An air cooled integrally bladed rotor with single crystals turbine rotor blades having cooling air passages formed into an equiax rotor disk, where a mold having expendable Molybdenum tooling and reusable molybdenum tooling is used to form the IBR. An annular blade ring with openings is used to secure the single crystal rotor blades within the mold, and a number of tube tools are inserted into a bottom end of each blade that forms a cooling air supply passage within the rotor disk. Two molybdenum circular shaped hubs are used to secure a bottom end of the tube tools with the mold. The mold is filled with metal powder and high pressure is used to solidify the powder to form the IBR. Expendable tooling is removed using sublimation when exposed to oxygen. Reusable tooling is reused to form additional IBRs.

Abstract: A small aero gas turbine engine with an axial thrust limiter device that uses compressed air acting on a rotating disk extending from a rotor of the engine in which a forward pressure chamber and an aft pressure chamber applies a pressure to both sides of the rotating disk. When rotor is shifted, one side of the rotating disk has an increase in pressure acting on it to shift the rotor in an axial direction. Each pressure chamber includes an upper variable restriction and a lower variable restriction in which the restriction varies due to axial movement of the rotor. A forward and an aft foil bearing can also be used in addition to axial balance the rotor when not enough pressure is available such as at engine startup.

Abstract: A process for retrofitting an electric power plant that uses two 60 Hertz large frame heavy duty industrial gas turbine engines to drive electric generators and produce electricity, where each of the two industrial engines can produce up to 350 MW of output power. The process replaces the two 350 MW industrial engines with one twin spool industrial gas turbine engine that is capable of producing at least 700 MW of output power. Thus, two prior art industrial engines can be replaced with one industrial engine that can produce power equal to the two prior art industrial engines.

Abstract: A power plant for an aircraft such as a UAV with a gas turbine engine that drives an electric generator to produce electrical power. The electric generator is rotatably supported by two foil bearings. A centrifugal compressor is secured to a forward side of the generator rotor shaft. The centrifugal compressor draws in cooling air that flows through the two foil bearings and between a space formed between the rotor coil and the stator coil of the electric generator to provide for cooling of both foil bearings and the coils of the generator.