Herein provided are methods and systems for controlling an engine having a variable geometry mechanism. A pressure ratio between a first pressure at an inlet of the engine and a predetermined reference pressure is determined. An output power for the engine is determined. The output power is adjusted based at least in part on the pressure ratio to obtain a corrected output power. A position control signal for a variable geometry mechanism of the engine is generated based on the corrected output power and the pressure ratio. The position control signal is output to a controller of the engine to control the variable geometry mechanism.

Hybrid electric propulsion systems are described. The systems include a gas turbine engine having low and high speed spools, each spool having a respective compressor and turbine. A mechanical power transmission is configured to at least one of extract power from and supply power to at least one of the low speed spool and the high speed spool, an electric machine is configured to augment rotational power of at least one of the spools, and a controller is operable to determine a rotational speed of the low speed spool, determine a rotational speed of the high speed spool, determine if a predetermined operational zone of operation based on the determined rotational speeds is present, and when a predetermined operational zone is determined, control a power augmentation of at least one spool to limit dwell operation of the gas turbine engine within the predetermined operational zone.

A gas turbine engine includes a compressor. A turbine is mechanically connected to the compressor by a shaft. An air-driven auxiliary turbine is in fluid communication with the compressor and is configured to receive pressurized air from the compressor. An auxiliary generator is operably connected to the auxiliary turbine. The auxiliary generator is configured to generate electrical energy in response to an operation of the auxiliary turbine. An energy storage device is in electrical communication with the auxiliary generator.

A method of maintaining rotor tip clearance and compressor operational line during a transient operation of a gas turbine engine is disclosed. In various embodiments, the method includes applying high spool auxiliary power to a high speed spool for a first time period, applying low spool auxiliary power to a low speed spool for a second time period, sensing one or more operational parameters of the gas turbine engine during the transient operation, and ceasing application of power to the high speed spool, based on the one or more operational parameters.

A gas turbine engine includes a compressor. A turbine is mechanically connected to the compressor by a shaft. An air-driven auxiliary turbine is in fluid communication with the compressor and is configured to receive pressurized air from the compressor. An auxiliary generator is operably connected to the auxiliary turbine. The auxiliary generator is configured to generate electrical energy in response to an operation of the auxiliary turbine. An energy storage device is in electrical communication with the auxiliary generator.

A turbine section for a gas turbine engine includes an independently controllable wheel downstream of the first static vane structure and a turbine rotor downstream of the independently controllable wheel. A method of generating thrust for a gas turbine engine, includes rotating a independently controllable wheel located downstream of a combustor and upstream of a turbine rotor to augment a swirl of a core flow combustion gases.

A system includes a gas turbine engine having a low speed spool, a high speed spool, and a combustor. The system also includes a low spool motor configured to augment rotational power of the low speed spool. The system further includes a controller configured to cause fuel flow. The controller is operable to control the low spool motor to drive rotation of the low speed spool responsive to a thrust command while the controller does not command fuel flow to the combustor.

A device for driving an integrated generator from an accessories relay box of a turbomachine. The device includes first and second electric motors arranged to transfer electric power from one to the other, one or more controllers configured for controlling said electric motors, and an epicyclic reduction gear train. The gear train includes a first element intended to be coupled to the accessories relay box, a second element intended to be coupled to the generator, and a third element driven to rotate by said first electric motor. The control means are configured to modify the speed of rotation of the third element in such a way that the second element is driven to rotate at a constant speed.

The present disclosure provides methods and systems for operating a multi-engine rotorcraft. The method comprises driving a rotor of the rotorcraft with a first engine while a second engine is de-clutched from a transmission clutch system that couples the rotor and the second engine, instructing the second engine to accelerate to a re-clutching speed, and controlling an output shaft speed of the second engine during acceleration of the second engine to the re-clutching speed by applying a damping function to a speed control loop of the second engine.

A gas turbine engine for an aircraft comprises a high-pressure (HP) spool comprising an HP compressor and a first electric machine driven by an HP turbine; a low-pressure (LP) spool comprising an LP compressor and a second electric machine driven by an LP turbine; a combustion system comprising a fuel metering unit; and an engine controller configured to, in response to a change of a power lever angle setting indicative of a deceleration event, reduce fuel flow to the combustion system by the fuel metering unit, and to operate the first electric machine in a generator mode to reduce the HP spool rotational speed and engine core mass flow.