Abstract: A turbo generator rotor assembly is provided and includes a generator, first and second bearings on a compressor-side and a turbine-side of the generator and a combination seal configuration in which leakage from the compressor cools the first bearing, the generator and the second bearing. The combination seal configuration leads to minimal leakage past the turbine with the generator and the first and second bearings being cooled with leakage flow from the compressor.

Abstract: Aircraft propulsion systems include aircraft systems having at least one hydrogen tank and an aircraft-systems heat exchanger and engine systems having at least a main engine core, a high pressure pump, a hydrogen-air heat exchanger, and a turbo expander. The main engine core includes a compressor section, a combustor section having a burner, and a turbine section. Hydrogen is supplied from the at least one hydrogen tank through a hydrogen flow path, passing through the aircraft-systems heat exchanger, the high pressure pump, the hydrogen-air heat exchanger, and the turbo expander, prior to being injected into the burner for combustion. The turbo expander includes a rotor separated into a first expander portion and a second expander portion arranged about an output shaft and the output shaft is operably connected to a generator configured to generate electrical power.

Abstract: Aircraft propulsion systems have aircraft systems including at least one hydrogen tank and an aircraft-systems heat exchanger and engine systems includes at least a main engine core, a high pressure pump, a hydrogen-air heat exchanger, and a turbo expander. The main engine core includes a compressor section, a combustor section having a burner, and a turbine section arranged along an engine shaft. Hydrogen is supplied from the at least one hydrogen tank through a hydrogen flow path, passing through the aircraft-systems heat exchanger, the high pressure pump, the hydrogen-air heat exchanger, and the turbo expander, prior to being injected into the burner for combustion. The turbo expander is configured to impart power to the engine shaft.

Abstract: A propulsion system for an aircraft includes a core engine that includes a core flow path that is in communication with a compressor section, combustor section and a turbine section, the core engine is configured to generate a high energy gas flow, a first cycle turbine that is configured to drive a first cycle compressor at a cycle speed in response to expansion of a heated working fluid flow between a first inlet and a first outlet of the first cycle turbine, and a first power turbine that is configured to drive a first output shaft at a power speed that is different than the cycle speed in response to expansion of a working fluid flow received from the first outlet of the first cycle turbine.

Abstract: A gas turbine engine includes a core engine that includes a core flow path where air is compressed in a compressor section, communicated to a combustor section, mixed with an ammonia based fuel and ignited to generate a high energy combusted gas flow that is expanded through a turbine section. The turbine section is mechanically coupled to drive the compressor section. An ammonia flow path communicates an ammonia flow to the combustor section. A cracking device is disposed in the ammonia flow path. The cracking device is configured to decompose the ammonia flow into a fuel flow containing hydrogen (H2). At least one heat exchanger is upstream of the cracking device that provides thermal communication between the ammonia flow and a working fluid flow such that the ammonia fluid flow accepts thermal energy from the working fluid flow.

Abstract: A gas turbine engine includes a core engine that includes a core flow path where air is compressed in a compressor section, communicated to a combustor section, mixed with an ammonia based fuel and ignited to generate a high energy combusted gas flow that is expanded through a turbine section. The turbine section is mechanically coupled to drive the compressor section. An ammonia flow path communicates an ammonia flow to the combustor section. A cracking device is disposed in the ammonia flow path. The cracking device is configured to decompose the ammonia flow into a fuel flow containing hydrogen (H2). At least one heat exchanger is upstream of the cracking device that provides thermal communication between the ammonia flow and a working fluid flow such that the ammonia fluid flow accepts thermal energy from the working fluid flow.

Abstract: Aircraft propulsion systems and aircraft are described. The aircraft propulsion systems include aircraft systems having at least one hydrogen tank and an aircraft-systems heat exchanger and engine systems having at least a main engine core, a high pressure pump, a hydrogen-air heat exchanger, and an expander, wherein the main engine core comprises a compressor section, a combustor section having a burner, and a turbine section. Hydrogen is supplied from the at least one hydrogen tank through a hydrogen flow path, passing through the aircraft-systems heat exchanger, the high pressure pump, the hydrogen-air heat exchanger, and the expander, prior to being injected into the burner for combustion.

Abstract: A turbo generator rotor assembly is provided and includes a generator, first and second bearings on a compressor-side and a turbine-side of the generator and a combination seal configuration in which leakage from the compressor cools the first bearing, the generator and the second bearing. The combination seal configuration leads to minimal leakage past the turbine with the generator and the first and second bearings being cooled with leakage flow from the compressor.

Abstract: Power generation systems are described. The systems include a shaft, a compressor operably coupled to a first end of the shaft, a turbine operably coupled to a second end of the shaft, a generator operably coupled to the shaft between the compressor and the turbine, and a working fluid arranged in a closed-loop flow path that flows through each of the compressor and the turbine to drive rotation of the shaft. The shaft includes an internal fluid conduit configured to receive a portion of the working fluid at one of the first end and the second end and convey the portion of the working fluid through the generator to the other of the first end and the second end, wherein the portion of the working fluid is rejoined with a primary flow path of the working fluid.

Abstract: A turbo-expanding cracking assembly includes a plurality of stages each including a rotating blade coupled to an output shaft and a fixed stator, at least one heat exchanger configured to transfer heat to an ammonia containing fuel flow, and a catalyst that is configured to decompose an ammonia containing fuel flow into a flow containing hydrogen (H2).

Abstract: Supercritical fluid systems and aircraft power systems are described. The systems include a compressor, a turbine, and a generator. A primary working fluid flow path has a primary working fluid that passes through the compressor, a separator, the turbine, and back to the compressor. A secondary working fluid flow path having a secondary working fluid that passes through the generator, the compressor, the separator, and back to the generator. The primary working fluid and the secondary working fluid are compressed and mixed within the compressor to form a mixture of the two fluids and the separator separates the mixture of the two fluids to direct the primary working fluid back to the turbine and the secondary working fluid to the generator.

Abstract: A turbine engine system includes at least one hydrogen fuel tank, a core flow path heat exchanger in a core flow path; and engine systems located in the core flow path. The engine system including at least a compressor section, a combustor section having a burner, and a turbine section. The core flow path heat exchanger is arranged in the core flow path downstream of the combustor section. The hydrogen fuel is supplied from the at least one hydrogen fuel tank through a hydrogen fuel supply line, passing through the core flow path heat exchanger and then supplied into the burner for combustion.

Abstract: A turbo-expanding cracking assembly includes a plurality of stages each including a rotating blade coupled to an output shaft and a fixed stator, at least one heat exchanger configured to transfer heat to an ammonia containing fuel flow, and a catalyst that is configured to decompose an ammonia containing fuel flow into a flow containing hydrogen (H2).

Abstract: Supercritical fluid systems and aircraft power systems are described. The systems include a compressor, a turbine, and a generator. A primary working fluid flow path has a primary working fluid that passes through the compressor, a separator, the turbine, and back to the compressor. A secondary working fluid flow path having a secondary working fluid that passes through the generator, the compressor, the separator, and back to the generator. The primary working fluid and the secondary working fluid are compressed and mixed within the compressor to form a mixture of the two fluids and the separator separates the mixture of the two fluids to direct the primary working fluid back to the turbine and the secondary working fluid to the generator.

Abstract: A turbo generator rotor assembly is provided and includes a generator, first and second bearings on a compressor-side and a turbine-side of the generator and a combination seal configuration in which leakage from the compressor cools the first bearing, the generator and the second bearing. The combination seal configuration leads to minimal leakage past the turbine with the generator and the first and second bearings being cooled with leakage flow from the compressor.

Abstract: Power generation systems are described. The systems include a shaft, a compressor operably coupled to a first end of the shaft, a turbine operably coupled to a second end of the shaft, a generator operably coupled to the shaft between the compressor and the turbine, and a working fluid arranged in a closed-loop flow path that flows through each of the compressor and the turbine to drive rotation of the shaft. The shaft includes an internal fluid conduit configured to receive a portion of the working fluid at one of the first end and the second end and convey the portion of the working fluid through the generator to the other of the first end and the second end, wherein the portion of the working fluid is rejoined with a primary flow path of the working fluid.

Abstract: Supercritical fluid systems and aircraft power systems are described. The systems include a compressor, a turbine operably coupled to the compressor, a generator operably coupled to the turbine and configured to generate power, a primary working fluid flow path having a primary working fluid configured to pass through the compressor, a separator, the turbine, and back to the compressor, and a secondary working fluid flow path passing through the generator, the compressor, the separator, and back to the generator. The primary working fluid is supercritical carbon dioxide (sCO2) and the secondary working fluid is a fluid having at least one of a density less than the primary working fluid and a molecular size smaller than the primary working fluid.

Abstract: A system includes a power cycle and a cooling cycle. The power cycle includes a first compressor, a recuperative heat exchanger, a waste-heat heat exchanger, and a turbine. The turbine includes a drive shaft coupled to the first compressor. The working fluid from the waste-heat heat exchanger drives the turbine, the drive shaft, and the first compressor. The recuperative heat exchanger cools the working fluid from the turbine, and at least one ram-air heat exchanger further cools the working fluid from the recuperative heat exchanger. The first compressor is configured to pressurize the working fluid from the at least one ram-air heat exchanger. The cooling cycle includes a pump, an isenthalpic valve, an ambient air heat exchanger, and a second compressor. The cooling cycle cools the working fluid and ambient air and is connected to the power cycle in the at least one ram-air heat exchanger.

Abstract: A variable vane system includes an outer platform, an inner casing radially inward from the outer casing and a vane extending between the inner and outer casings defining a vane axis. An inner vane stem is engaged with the inner casing and an outer vane stem is engaged with the outer casing. The system includes a bearing gap defined radially with respect to the vane axis between each of the inner and outer casings and respective vane stems for allowing the vane to rotate about the vane axis for varying angle of attack. The system includes a pressurized air supply inlet in fluid communication with at least one of the bearing gaps to form a stem air bearing to intermittently float at least one of the vane stems for controlled rotation about the vane axis.

Abstract: A variable vane system includes an outer platform defining a centerline axis, an inner platform radially inward from the outer platform with respect to the centerline axis and a vane extending between the inner and outer platforms defining a vane axis. The vane has an inner vane stem and an opposed outer vane stem. The inner vane stem is engaged with the inner platform and the outer vane stem is engaged with the outer platform. The system includes a bearing gap defined radially with respect to the vane axis between each of the inner and outer platforms and respective vane stems for allowing the vane to rotate about the vane axis for varying angle of attack. The system includes a pressurized air supply inlet in fluid communication with at least one of the bearing gaps to form a stem air bearing to intermittently float at least one of the vane stems for controlled rotation about the vane axis.