Waste heat management systems are described. The waste heat management systems include a turbine engine having a compressor section, a combustor section, a turbine section, and a nozzle. The compressor section, the combustor section, the turbine section, and the nozzle define a core flow path that expels through the nozzle. The waste heat management systems also include an auxiliary power unit (APU) system and a waste heat recovery system operably connected to the APU system. The APU system is integrated into a working fluid flow path of the waste heat recovery system.

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.

An air turbine starter that includes a housing. The housing can circumscribe a turbine coupled that is coupled to a gear train in a gear box via a drive shaft. The gear train can couple to an output shaft via at least a carrier. The air turbine starter can include at least a first bearing assembly and a second bearing assembly to rotatably support one or more of the drive shaft, the carrier, or the output shaft.

For aircraft taxiing, an aircraft is equipped with an electric machine installed in a propulsor gearbox (PGB), in parallel to the gas turbine, working in motor mode during taxi, and in generator mode during flight phases (such as take-off, climb, cruise, descent, approach and landing). Typical current systems which use an electric machine in the PGB do not use the electric machine in motor mode for taxi operations (i.e., it is only an additional generator). An optimized power supply providing a combination of a thermal engine such as an Auxiliary Power Unit (APU) and an electric energy storage system such as a battery provides power to the PGB electric machine even when the gas turbine is off.

An engine system includes an engine duct and a tail cone arranged radially inwardly of the engine duct. The tail cone has an outer surface and an inner surface. A generator housing is arranged in the tail cone. The generator housing includes an outer surface portion spaced from the inner surface of the tail cone. A generator is mounted in the generator housing. An air duct extends from the generator, through the generator housing, through the tail cone, and through the engine duct. The air duct includes an opening exposed to an air stream passing over the engine duct.

A method and system for controlling fuel flow to an aircraft engine during start are provided. Following light-off, an actual value of at least one engine operating parameter is obtained. Based on a difference between the actual value and a target value, a first command is generated to cause fuel flow to be provided to the engine's combustor according to a computed fuel flow rate defined by a fuel schedule of the engine. When the computed fuel flow rate is within a fuel flow rate limit, the first command is output. Otherwise, a limiting factor is applied to the computed fuel flow rate to limit a reduction in fuel flow to the combustor and a limited fuel flow rate is obtained, and a second command is output to cause fuel flow to be provided to the combustor according to the limited fuel flow rate.

A vehicle includes a vehicle body, a vehicle power source, and an actuator. The vehicle power source includes a housing and a power generator. The housing is rotationally mounted on the vehicle body and is configured to rotate, relative to the vehicle body, about a first rotational axis. The power generator is rotationally mounted within the housing and is configured to rotate about a second rotational axis and generate power. The first rotational axis and the second rotational axis are orthogonally disposed. The actuator is coupled to the housing and is operable to selectively rotate the housing about the first rotational axis. By gimballing the rotating mass of the power source a gyroscopic torque can be applied to the vehicle improving its maneuverability.

An air turbine starter includes a support structure and a turbine having a shaft and a rotor that extends away from the shaft in a radial direction. The air turbine starter also includes a mount structure that supports the turbine for rotation relative to the support structure. The mount structure is configured to transfer a force from the turbine to the support structure. The mount structure includes a deformable member that is configured to deform when the force exceeds a predetermined threshold.

An aircraft system includes a component configured to operate with a minimum power demand. The aircraft system also includes an auxiliary power unit including an engine. The auxiliary power unit is configured to power the component and to operate the engine in a plurality of operating modes including a power mode and a standby mode. The auxiliary power unit generates a first power output at least equal to the minimum power demand during the power mode. The auxiliary power unit generates a second power output less than the minimum power demand during the standby mode.

Systems and methods for controlling an auxiliary power unit (APU) are provided. The systems and methods may comprise detecting an operating condition of the APU, determining an optimal APU frequency in response to the operating condition, and setting an angular velocity of the APU to the optimal APU frequency.