In-flight hybrid electric engine shutdown
A method for operating a hybrid-electric propulsion system of an aircraft is provided. The hybrid-electric propulsion system includes a gas turbine engine having a high pressure system, a low pressure system, and an electric machine coupled to one of the high pressure system or low pressure system. The method includes receiving data indicative of an actual or anticipated in-flight shutdown of the gas turbine engine; and adding power to the gas turbine engine through the electric machine in response to receiving data indicative of the actual or anticipated in-flight shutdown of the gas turbine engine.
1 . A method for operating a hybrid-electric propulsion system of an aircraft, the hybrid-electric propulsion system comprising a gas turbine engine having a starter system, a high pressure system, a low pressure system, a first electric machine coupled to the low pressure system, and a second electric machine coupled to the high pressure system, the first electric machine and the second electric machine separate from the starter system, the method comprising:
during a flight, receiving data indicative of an actual or anticipated in-flight shutdown of the gas turbine engine; and
during the flight, adding power to the gas turbine engine within five seconds after receiving data of the actual in-flight shutdown through the first electric machine and the second electric machine in response to receiving data indicative of the actual or anticipated in-flight shutdown of the gas turbine engine;
wherein adding power to the gas turbine engine comprises adding power using the first electric machine and the second electric machine to maintain a rotation speed of the low pressure system and the high pressure system of at least 25% of a pre-shutdown rotation speed of the low pressure system and the high pressure system throughout the actual in-flight shutdown and a subsequent restart of the gas turbine engine,
wherein adding power to the gas turbine engine comprises adding at least 10 horsepower and up to 1000 horsepower,
wherein adding power to the gas turbine engine comprises adding power to the high pressure system to reduce an exhaust gas temperature of the gas turbine engine by at least 10° Celsius and up to 100° Celsius, and
wherein adding power to the gas turbine engine includes adding power to the low pressure system of the gas turbine engine using the first electric machine embedded within the gas turbine engine at a location aft of a turbine section of the gas turbine engine and inward of a core airflow path through the gas turbine engine to reduce a rate of deceleration of components of the gas turbine engine following the actual in-flight shutdown, decrease a first amount of time required for the gas turbine engine to get back to the pre-shutdown rotational speed following the actual in-flight shutdown, and reduce altitude loss during the subsequent restart of the gas turbine engine; and adding power to the high pressure system of the gas turbine engine using the second electric machine in electrical communication with an electric power bus and inward of the core airflow path through the gas turbine engine to reduce the rate of deceleration of the components of the gas turbine engine following the actual in-flight shutdown, decrease the first amount of time required for the gas turbine engine to get back to the pre- shutdown rotational speed following the actual in-flight shutdown, and reduce altitude loss during the subsequent restart of the gas turbine engine.
2 . The method of claim 1 , wherein receiving data indicative of the actual or anticipated in-flight shutdown of the gas turbine engine comprises receiving data indicative of the actual in-flight shutdown of the gas turbine engine.
3 . The method of claim 2 , further including
initiating a re-start of the engine after a second amount of time after receiving data indicative of the actual in-flight shutdown of a gas turbine engine, wherein adding power to the gas turbine engine includes adding power to the gas turbine engine substantially continuously until the re-start process is initiated and adding power to the gas turbine engine substantially continuously until the engine is re-ignited.
4 . The method of claim 3 , wherein the second amount of time is at least 10 seconds.
5 . The method of claim 1 , wherein receiving data indicative of the actual or anticipated in-flight shutdown of the gas turbine engine comprises determining an anticipated in-flight shutdown of the gas turbine engine.
6 . The method of claim 1 , wherein adding power to the gas turbine engine includes adding power to the low pressure system of the gas turbine engine using the first electric machine to maintain a rotation speed of the low pressure system within 75% of the pre-shutdown rotational speed.
7 . The method of claim 1 , wherein adding power to the gas turbine engine includes adding power to the low pressure system of the gas turbine engine using the first electric machine to maintain the rotation speed of the low pressure system above 25% of a maximum corrected speed of the low pressure system.
8 . The method of claim 1 , wherein adding power to the gas turbine engine includes providing electrical power to the first electric machine and the second electric machine from an external source.
9 . The method of claim 8 , wherein adding power to the gas turbine engine includes providing electrical power to the first electric machine from electric energy storage units and an auxiliary power unit.
10 . The method of claim 1 , wherein adding power to the gas turbine engine includes adding at least 10 horsepower.
11 . The method of claim 1 , wherein adding power to the gas turbine engine includes adding at least 50 horsepower.
12 . The method of claim 1 , wherein adding power to the gas turbine engine comprises adding at least 100 horsepower and up to 1000 horsepower.
13 . The method of claim 1 , wherein adding power to the gas turbine engine comprises adding power to the high pressure system to reduce the exhaust gas temperature of the gas turbine engine by at most 100° Celsius.
14 . A hybrid-electric system comprising:
a gas turbine engine having a starter system, a high pressure system, a low pressure system, an electric machine coupled to one of the high pressure system or low pressure system, the electric machine separate from the starter system, and a controller, the controller including memory and one or more processors, the memory storing instructions that when executed by the one or more processors cause the system to perform one or more functions, the functions including:
during a flight, receiving data indicative of an actual or anticipated in-flight shutdown of the gas turbine engine;
during the flight, adding power within five seconds after receiving data of the actual in-flight shutdown to the gas turbine engine through the electric machine in response to receiving data indicative of the actual or anticipated in-flight shutdown of the gas turbine engine; and
maintaining, with the electric machine, a rotation speed of the low pressure system and the high pressure system of at least 25% of a pre-shutdown rotation speed of the low pressure system and the high pressure system throughout the actual in-flight shutdown and subsequent restart of the gas turbine engine,
wherein adding power to the gas turbine engine comprises adding at least 10 horsepower and up to 1000 horsepower,
wherein adding power to the gas turbine engine comprises adding power to the high pressure system to reduce an exhaust gas temperature of the gas turbine engine by at least 10° Celsius and up to 100° Celsius, and
wherein the electric machine comprises a low pressure electric machine embedded within the gas turbine engine at a location aft of a turbine section of the gas turbine engine and inward of a core airflow path through the gas turbine engine and a high pressure electric machine in electrical communication with an electric power bus and inward of the core airflow path through the gas turbine engine, wherein adding power to the gas turbine engine includes adding power to the low pressure system of the gas turbine engine using the low pressure electric machine to reduce a rate of deceleration of components of the gas turbine engine following the actual in-flight shutdown, decrease a first amount of time required for the gas turbine engine to get back to the pre-shutdown rotational speed following the actual in-flight shutdown, and reduce altitude loss during the subsequent restart of the gas turbine engine; and adding power to the high pressure system of the gas turbine engine using the high pressure electric machine to reduce the rate of deceleration of the components of the gas turbine engine following the actual in-flight shutdown, decrease the first amount of time required for the gas turbine engine to get back to the pre-shutdown rotational speed following the actual in-flight shutdown, and reduce altitude loss during the subsequent restart of the gas turbine engine.
15 . The hybrid-electric system of claim 14 , wherein receiving data indicative of the actual or anticipated in-flight shutdown of the gas turbine engine comprises receiving data indicative of the actual in-flight shutdown of the gas turbine engine.