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 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.

Abstract: A heat shield manifold system for an inner casing between a compressor and turbine assembly is disclosed. The heat shield manifold system protects the outer case from high temperature compressor discharge air, thereby enabling the outer case extending between a compressor and a turbine assembly to be formed from less expensive materials than otherwise would be required. In addition, the heat shield manifold system may be configured such that compressor bleed air is passed from the compressor into the heat shield manifold system without passing through a conventional flange to flange joint that is susceptible to leakage.

Abstract: A turbine exhaust casing having an outer casing, an inner casing, an annular exhaust gas path defined between outer and inner flow path walls, and a turbine exhaust casing cavity located radially outward and radially inward from the gas path. A plurality of structural struts support the inner casing to the outer casing, and a fairing surrounds each of the struts in an area extending between the outer and inner flow path walls. A first purge air path extends through at least one of the struts for conducting purge cooling air radially inward to the inner casing, and a second purge air path extends through the strut for further conducting the purge cooling air radially outward to provide a flow of purge air to a location of the exhaust casing cavity radially outward from the outer flow path wall.

Abstract: A heat shield manifold system for an inner casing between a compressor and turbine assembly is disclosed. The heat shield manifold system protects the outer case from high temperature compressor discharge air, thereby enabling the outer case extending between a compressor and a turbine assembly to be formed from less expensive materials than otherwise would be required. In addition, the heat shield manifold system may be configured such that compressor bleed air is passed from the compressor into the heat shield manifold system without passing through a conventional flange to flange joint that is susceptible to leakage.

Abstract: A turbine exhaust casing having an outer casing, an inner casing, an annular exhaust gas path defined between outer and inner flow path walls, and a turbine exhaust casing cavity located radially outward and radially inward from the gas path. A plurality of structural struts support the inner casing to the outer casing, and a fairing surrounds each of the struts in an area extending between the outer and inner flow path walls. A first purge air path extends through at least one of the struts for conducting purge cooling air radially inward to the inner casing, and a second purge air path extends through the strut for further conducting the purge cooling air radially outward to provide a flow of purge air to a location of the exhaust casing cavity radially outward from the outer flow path wall.

Abstract: A small single use gas turbine engine with a twin spool rotor shaft and a bypass fan, the rotor shafts being supported for rotation by bearings in the front and rear compartments of the engine. A portion of the bypass fan air is diverted to flow through the bearings in order to provide for cooling of the high speed bearings. Because a large amount of cooling air is required to cool the bearings, an air in tube is positioned in each of the guide vanes in the turbine section to provide for a cooling air passage leading into the rear bearings. In the front bearings, cooling air from the bypass fan is bled off from a location just upstream from the entrance to the centrifugal compressor. A fuel mist tube supplies fuel mist to the cooling air before passing through the bearings to provide extra cooling for the bearings and to provide lubrication to improve the service life of the engine.

Abstract: A small twin spool gas turbine engine with a bearing support arrangement in which the bearings are dampened by O-rings secured between the bearing races and the support structure, and in which the bearings are arranged in series so that a cooling air can be passed through the bearings to prevent overheating. The aft end of the engine includes high speed and low speed ball bearings supported with preload springs to add additional damping capability. The fore and aft end bearing support assemblies forms a cooling air path for the cooling fluid to flow through a passage within one of the guide vanes, through the bearings and out through a hole in the low pressure turbine rotor disk. the bearing cooling air passage includes a snorkel tube that extends from a guide vane cooling air passage and into the bypass air channel to draw in the cooling air used for the bearings. The snorkel tube includes a slanted opening so that dirt particulates do not enter the bearing cooling air passage.

Abstract: A small twin spool gas turbine engine with a bearing support arrangement in which the bearings are dampened by O-rings secured between the bearing races and the support structure, the bearings are arranged in series so that a cooling air can be passed through the bearings to prevent overheating, and the bearings are dry lubricated. The aft end of the engine includes high speed and low speed ball bearings supported with preload springs to add additional damping capability. The end bearing support assemblies form a cooling air path for the cooling fluid to flow through a passage within one of the guide vanes, through the bearings and a hole in the low pressure turbine rotor disk and out the exhaust of the engine. A snorkel tube extends into the bypass air channel drawing air for the bearings, and has a slanted opening preventing dirt particulates from entering the bearing cooling passage.

Abstract: A process for optimizing a blade tip clearance for a rub tolerate design in a gas turbine engine that includes evaluating a selection of candidate materials for galling and heat generation, selecting a subset of the candidate materials and analyze engine transient tip clearance for the subset materials, verifying the optimum material cooling and heat shielding for tip clearance and structures, and analyze and select an engine break-in procedure for the optimum tip clearance between turbine and compressor. If one of the subset materials results in a poor performance, than another material from the candidate materials is selected and reanalyzed until the best materials have been found. When the best materials are found, then a finite element method of analysis is performed from the blade and the static parts that form the tip clearance is performed to evaluate the materials for damage. If required, the blade and tip squealer configuration is altered to reduce stress, or blade tip coating is used.

Abstract: A cooled fluid flow component for a combustion engine which employs internal impingement and exterior surface film cooling is disclosed. The fluid flow component has improved tolerance to assembly and manufacturing variations. The fluid flow component includes at least one interior cavity having an associated impingement sleeve. An impingement annulus surrounding the impingement sleeve is divided into more than one region, with each region forced to have a pressure equal, pressure, with the pressure induced being sufficient to provide adequate backflow margin. The external cooling holes are shaped to address possible overflow tendencies, and the impingement holes are adapted to reduce or eliminate possible losses of impingement cooling effectiveness.

Abstract: A cooled fluid flow component for a combustion engine which employs internal impingement and exterior surface film cooling is disclosed. The fluid flow component has improved tolerance to assembly and manufacturing variations. The fluid flow component includes at least one interior cavity having an associated impingement sleeve. An impingement annulus surrounding the impingement sleeve is divided into more than one region, with each region forced to have a pressure equal, pressure, with the pressure induced being sufficient to provide adequate backflow margin. The external cooling holes are shaped to address possible overflow tendencies, and the impingement holes are adapted to reduce or eliminate possible losses of impingement cooling effectiveness.