Mechanical flywheel for bowed rotor mitigation

An aircraft comprising:

• an aircraft engine including a rotor shaft, wherein the rotor shaft is inside a casing;
• a flywheel;
• a transmission connecting the rotor shaft and the flywheel, wherein;
• second rotational energy in the flywheel is generated from first rotational energy of the rotor shaft transmitted to the flywheel through the transmission,
• after shutdown of the aircraft engine, the transmission drives the rotor shaft using a portion of the second rotational energy when the aircraft engine is cooling down in a temperature gradient in the casing;
• the casing comprises trapped air creating the temperature gradient perpendicular to a longitudinal axis of the rotor shaft, and
• the portion of the second rotational energy driving the rotor shaft reduces or prevents thermal bowing of the rotor shaft in the temperature gradient and;
• further comprising:
• a computer connected to an electrical system;
• and
• wherein the transmission includes:
• a first transmission connected to a gearbox;
• the gearbox connected to a first generator;
• the first generator connected to a motor;
• a second transmission connecting the motor to the flywheel;
• and
• a second generator connected to the flywheel;
• and
• wherein:
• the first generator converts a portion of the first rotational energy of the rotor shaft into first electrical energy when the first transmission and the gearbox transfer the first rotational energy of the rotor shaft to the first generator,
• the motor drives the flywheel when powered using the first electrical energy, thereby generating the second rotational energy in the flywheel,
• the second generator converts a portion the second rotational energy into second electrical energy powering the electrical system during times of peak electrical loading of the electrical system, when the second generator is driven by the flywheel, and
• the computer reduces fuel consumption in the aircraft engine engine as compared to when the aircraft engine engine is used to power the electrical system during the times of peak electrical loading without the flywheel.

An apparatus, comprising:

• a gas turbine engine having a rotor shaft;
• a flywheel;
• and
• a first transmission connecting the rotor shaft to a gearbox, wherein:
• the flywheel is connected to the gearbox, or
• the gearbox is connected to a first generator, the first generator is connected to a first motor, a second transmission connects the flywheel to the first motor, and a third transmission connects the flywheel to a second generator;
• and
• an electrical system connected to the second generator;
• wherein:
• flywheel rotational energy in the flywheel is generated from rotational energy of the rotor shaft transmitted to the flywheel using the first transmission;
• the second generator converts a portion of the flywheel rotational energy into second electrical energy, and
• the second electrical energy powers the electrical system powering air conditioning on an aircraft, or powering cabin pressurization on the aircraft, or powering the air conditioning and the cabin pressurization.

A method for transferring energy, comprising:

• driving a flywheel using a rotor shaft in an aircraft engine assembly, thereby generating flywheel rotational energy;
• driving the rotor shaft using a portion of the flywheel rotational energy after shutdown of the aircraft engine assembly when the aircraft engine assembly is cooling down in a temperature gradient wherein;
• the rotor shaft is inside a casing comprising trapped air creating the temperature gradient perpendicular to a longitudinal axis of the rotor shaft, and
• the driving reduces or prevents thermal bowing of the rotor shaft in the temperature gradient;
• and/or
• converting a portion of the flywheel rotational energy into electrical energy;
• using the electrical energy to power an electrical system on an aircraft during times of peak electrical loading of the electrical system, the electrical system powering air conditioning on the aircraft, or powering cabin pressurization on the aircraft, or powering the air conditioning and the cabin pressurization;
• and
• reducing fuel consumption in the aircraft engine assembly as compared to when the aircraft engine assembly is used to power the electrical system during the times of peak electrical loading without the flywheel.