Provided is a turbo fan engine (TF) provided with a power transmission device that switches main shafts (MSs) connected to a starter generator (SG) so as to perform power transmission, between at startup and after the startup. The TF includes a first MS and a second MS. The power transmission device includes a first shaft, an intermediate shaft, and a second shaft that are coaxially disposed, and a clutch. The first shaft is connected to the first MS through bevel gears, the intermediate shaft is disposed outside of the first shaft and is connected to the SG through bevel gears, and the second shaft is disposed outside of the intermediate shaft and is connected to the second MS through bevel gears. When, out of any two adjacent shafts of the first shaft, the intermediate shaft, and the second shaft, an inner shaft tries to rotate at a speed higher than a speed of an outer shaft, the clutch causes the both shafts to engage with each other and to rotate at the same speed, and transmits power, whereas when the outer shaft tries to rotate at a speed higher than a speed of the inner shaft, the clutch causes the both shafts to disengage from each other, and does not transmit power.

Provided is a turbo fan engine (TF) provided with a power transmission device that switches main shafts (MSs) connected to a starter generator (SG) so as to perform power transmission, between at startup and after the startup. The TF includes a first MS and a second MS. The power transmission device includes a first shaft, an intermediate shaft, and a second shaft that are coaxially disposed, and a clutch. The first shaft is connected to the first MS through bevel gears, the intermediate shaft is disposed outside of the first shaft and is connected to the SG through bevel gears, and the second shaft is disposed outside of the intermediate shaft and is connected to the second MS through bevel gears. When, out of any two adjacent shafts of the first shaft, the intermediate shaft, and the second shaft, an inner shaft tries to rotate at a speed higher than a speed of an outer shaft, the clutch causes the both shafts to engage with each other and to rotate at the same speed, and transmits power, whereas when the outer shaft tries to rotate at a speed higher than a speed of the inner shaft, the clutch causes the both shafts to disengage from each other, and does not transmit power.

Methods and systems for controlling windmilling in an engine are described. An electric starter motor is coupled to the engine, a circuit element is coupled to the electric starter engine and to a DC signal source, and a control system coupled to the engine and to the circuit element. The control system is configured for: determining whether the engine is in a windmilling state; when the engine is in a windmilling state, commanding the circuit element to apply a DC signal to the electric starter motor; and modulating the DC signal applied to the electric starter motor to control a level of rotational motion of the engine.

A system is provided for alternating starter use during multi-engine motoring in an aircraft. The system includes a first engine starting system of a first engine. A first controller is in communication with a second controller that controls a second engine starting system of a second engine, the first controller being configured to intermittently direct power to the first engine starting system to alternately accelerate and decelerate the first engine during motoring with respect to the second engine.

Disclosed is a turbomachine, comprising a gas generator (13) equipped with a first shaft (18), at least one reversible electrical machine (11), a free turbine (12) provided with a second shaft (17) and caused to rotate by a gas flow generated by the gas generator (13), an accessory gear box (14) and at least one accessory (15, 16).

Said at least one electrical machine (11) is mechanically coupled to said second mechanical shaft (17) via the accessory gear box (14) during all phases of operation of the turbomachine (10), the accessory gear box (14) is coupled to the at least one accessory (15, 16) and the turbomachine (10) further comprises a single mechanical coupling means (20) for mechanically coupling said first mechanical shaft (18) to the accessory gear box (14) in a first configuration and mechanically uncoupling said first mechanical shaft (18) from the accessory gear box (14) in a second configuration.

Disclosed is a turbomachine, comprising a gas generator (13) equipped with a first shaft (18), at least one reversible electrical machine (11), a free turbine (12) provided with a second shaft (17) and caused to rotate by a gas flow generated by the gas generator (13), an accessory gear box (14) and at least one accessory (15, 16).

Said at least one electrical machine (11) is mechanically coupled to said second mechanical shaft (17) via the accessory gear box (14) during all phases of operation of the turbomachine (10), the accessory gear box (14) is coupled to the at least one accessory (15, 16) and the turbomachine (10) further comprises a single mechanical coupling means (20) for mechanically coupling said first mechanical shaft (18) to the accessory gear box (14) in a first configuration and mechanically uncoupling said first mechanical shaft (18) from the accessory gear box (14) in a second configuration.

A method for regulating the temperature of the exhaust gases of a turbomachine, the method including regulation of the injection of fuel into a combustion chamber of the turbomachine so that the turbomachine generates a target thrust; regulation of the injection of mechanical power by an electric motor onto a shaft driven in rotation by a turbine, the electric motor being activated when a clearance between a casing and the blades of the turbine exceeds a threshold value.

An aspect of the present disclosure is directed to a method for mitigating rotor bow in a turbo machine. The method includes rotating a rotor over a first period of time; discontinuing rotation of the rotor for a second period of time; and iterating, over an overall period of time, rotation of the rotor over the first period of time and discontinuing rotation of the rotor for the second period of time.

A gas turbine propulsion system includes a shroud that defines a fluid flow path. A gas turbine engine in the fluid flow path includes a compressor, a combustor downstream from the compressor, and a turbine downstream from the combustor. An electric generator in the fluid flow path includes a rotor coaxially aligned with the turbine. A propulsor is upstream from the gas turbine engine, and an electric motor is operably coupled to the propulsor to rotate the propulsor. The propulsor is rotationally isolated from the gas turbine engine so that the propulsor rotates independently from operation of the gas turbine engine.

A method for protecting, on spin-up, an aircraft engine including a power supply source, an engine with a rotor and associated with a starter system to, when supplied with power, produce a mechanical force to spin the rotor. The method includes an acquisition step performed continuously, wherein the engine control avionics acquire rotational speed of the rotor, a comparison step wherein the engine control avionics continuously compare acquired rotational speed against a predetermined rotational speed, and a checking step wherein the engine control avionics check that rotation of the rotor corresponds to deliberate pilot action, and if so, the engine control avionics authorize supply of power to the starter system, and, if not, in a deactivation step, the engine control avionics disconnect the engine starter system from its power supply source in order to stop the rotation of the rotor.