An electrical assembly for an aeronautical turbomachine, including an electric machine configured to be disposed in a turbomachine and comprising a stator and a rotor comprising magnets, the assembly including a short-circuit detecting means, a hot air injecting means configured to draw hot air off the turbomachine at a temperature greater than the temperature of demagnetization of the magnets of the rotor, and to inject the drawn hot air onto the magnets of said rotor when the short-circuit detecting means detects the presence of a short-circuit in the electric machine, and a cool air injecting means, configured to draw cool air off the turbomachine and to inject it into an inner chamber of the turbomachine, the temperature of the cool air drawn by the cool air injecting means being less than the temperature of the hot air drawn by the hot air injecting means.

In accordance with at least one aspect of this disclosure, there is provided a method of accelerating a gas turbine engine. The method includes adding torque to a core of the gas turbine engine to accelerate rotation of the core by controlling fuel flow to a plurality of fuel injectors of the gas turbine engine. The method also includes adding torque to the core by powering an electric machine that is operatively connected to the core. In embodiments, controlling fuel flow to the plurality of fuel injectors is based on feedback from the electric machine.

In some examples, a gas turbine engine including a high-pressure (HP) spool assembly including a HP shaft, a HP compressor and HP turbine; a lower pressure (LP) spool assembly including a LP shaft and LP turbine; a motor-generator coupled to the LP shaft; and a controller. The controller is configured to control the motor-generator to operate in a motor mode to apply torque the LP shaft during a starting of the HP spool assembly, and control the motor-generator to operate in a generator mode for a least a period of time following the starting of the HP spool assembly.

A hybrid electric propulsion system includes a gas turbine engine having a low speed spool and a high speed spool. The low speed spool includes a low pressure compressor and a low pressure turbine, and the high speed spool includes a high pressure compressor and a high pressure turbine. The hybrid electric propulsion system also includes an energy storage system, an electric motor configured to augment rotational power of the high speed spool, and a controller. The controller is operable to detect a start condition of the gas turbine engine, control power delivery from the energy storage system to the electric motor based on detecting the start condition, and provide a compressor stall margin using a power-assist provided by the electric motor to the high speed spool over a targeted speed range during starting of the gas turbine engine.

A twin-engine system includes a gas turbine engine comprising a core and a first output shaft drivable by the core. An electric engine has an electric motor configured to drive a second output shaft. A reduction gear box (RGB) has an RGB input drivingly engaged to both the first output shaft and the second output shaft. The RGB has an RGB output to provide rotational output to a rotatable load.

A hybrid power system for an aircraft comprises a gas turbine connected to a generator for generating electrical power; an electrical storage device configured to output electrical power; a propulsor; a motor operable to drive the propulsor using electrical power from either or both of the generator and the electrical storage device; and a controller. The controller, to meet propulsor power demand, is configured to control an amount of electrical power generated by the generator, and an amount of electrical power outputted by the electrical storage device. In a first control mode coinciding with an increase in the propulsor power demand sufficient to cause a transient excursion of the operating point of a compressor of the gas turbine from a steady state working line, the controller is further configured to temporarily increase the amount of electrical power outputted by the electrical storage device such that the transient excursion is reduced.

An aircraft that includes a hybrid-electric propulsion system is provided. In one aspect, the hybrid-electric propulsion system includes at least one propulsor that includes a gas turbine engine and an electric machine mechanically coupled with a spool of the gas turbine engine. When idle operation is commanded, electrical power is provided to the electric machine to cause the electric machine to apply torque to the spool and fuel provided to the engine can be reduced. Thus, the electric machine is controlled to provide a power assist to maintain the engine at the commanded idle speed whilst reducing fuel consumption.

A fuel tank heat dissipation system for fuel cell (FC) cooling is disclosed. in one example, at least one FC is in thermal communication with an intermediary heat exchanger. A fuel tank is also in fluid communication with the intermediary heat exchanger. A fluid is used to receive heat from the intermediary heat exchanger and flow along a first fluid path to the fuel tank. A nozzle is used to spray the fluid about an interior surface of the fuel tank, where the spray of the fluid about the interior of the fuel tank allows the fluid to dissipate the heat. A second fluid path from the fuel tank to the intermediary heat exchanger, the second fluid path to return the fluid that has dissipated the heat to the intermediary heat exchanger.

A cooling system for an aircraft comprises a gas turbine engine, an ancillary apparatus, and a heat exchanger. The gas turbine engine comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate an electrical power P.sub.EM1 (W). The heat exchanger is configured to transfer a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger, and a ratio S of:

[00001]$S=\frac{\left(\mathrm{Total}\mathrm{Electrical}\mathrm{Power}\mathrm{Generated}=P_{\mathrm{EM}1}\right)}{\left(\mathrm{Total}\mathrm{Heat}\mathrm{Energy}\mathrm{Rejected}\mathrm{to}\mathrm{Airflow}=Q\right)}$

is in a range of between 0.50 and 5.00.

The gas turbine engine can have an engine core; a core output shaft drivable by the engine core; a power output shaft; an auxiliary power shaft; and a reduction gearbox having gears, the gears drivingly connecting the core output shaft to the auxiliary power shaft. The gears can include an epicyclic gearing drivingly connecting the core output shaft and the auxiliary power shaft to the power output shaft. The gas turbine engine can further have a second auxiliary power shaft interconnected to the auxiliary power shaft, the power output shaft, and the core output shaft by the gears.