Abstract: In some examples, a system including a gas turbine engine, the engine including a high-pressure (HP) shaft; HP compressor; HP turbine, second shaft; second compressor; second turbine, the second turbine being coupled to the second compressor via the second shaft (e.g., LP shaft); and a generator coupled to the LP shaft. The generator is configured to generate electrical power from rotation of the LP shaft, and increase electrical power generated by the generator to increase a torque applied to the LP shaft by the generator, e.g., in combination with reduction in engine thrust, or in response to the detection of a stall and/or surge of the engine. The increase in torque applied to the second shaft is configured to increase a rate at which a rotational speed of the second shaft decreases, e.g., in combination with the reduction in engine thrust or during the stall/surge of the engine.

Abstract: Gas turbine engines include an engine frame defining an inner radial surface, a shaft rotatably mounted in the engine frame along a longitudinal axis, and an electric machine that includes a rotor coupled to the shaft and a stator coupled to the engine frame and defining an outer radial surface. In some gas turbine engines, the engine frame includes inlet and outlet fluid passages, each extending to a portion of the inner radial surface. The portion of the inner radial surface of the engine frame is spaced from the outer radial surface of the stator to form an annular fluid passage around the stator of an electric machine. The annular fluid passage is configured to direct a cooling fluid around the stator to remove heat from the stator. Some gas turbine engines include two or more positioning keys configured to fix the stator relative to the engine frame.

Abstract: 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.

Abstract: Gas turbine engines include an engine frame defining an inner radial surface, a shaft rotatably mounted in the engine frame along a longitudinal axis, and an electric machine that includes a rotor coupled to the shaft and a stator coupled to the engine frame and defining an outer radial surface. In some gas turbine engines, the engine frame includes inlet and outlet fluid passages, each extending to a portion of the inner radial surface. The portion of the inner radial surface of the engine frame is spaced from the outer radial surface of the stator to form an annular fluid passage around the stator of an electric machine. The annular fluid passage is configured to direct a cooling fluid around the stator to remove heat from the stator. Some gas turbine engines include two or more positioning keys configured to fix the stator relative to the engine frame.

Abstract: A cooling system includes a first cooling loop, a second cooling loop and a heat exchanger configured to transfer heat from the first cooling loop to the second cooling loop. The first cooling loop includes a flow restrictor, an inertial separator, and a pressure relief valve cooperating to effect diversion of vapor present in the first cooling loop due to a leak between the first cooling loop and the second cooling loop.

Abstract: A redundant oil and fuel pumping system for use with a gas turbine engine. The pumping system includes a plurality of power sources, a fuel system and an oil system. The fuel system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power sources. The oil system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power sources.

Abstract: In some examples, a system including a gas turbine engine, the engine including a high-pressure (HP) shaft; HP compressor; HP turbine, second shaft; second compressor; second turbine, the second turbine being coupled to the second compressor via the second shaft (e.g., LP shaft); and a generator coupled to the LP shaft. The generator is configured to generate electrical power from rotation of the LP shaft, and increase electrical power generated by the generator to increase a torque applied to the LP shaft by the generator, e.g., in combination with reduction in engine thrust, or in response to the detection of a stall and/or surge of the engine. The increase in torque applied to the second shaft is configured to increase a rate at which a rotational speed of the second shaft decreases, e.g., in combination with the reduction in engine thrust or during the stall/surge of the engine.

Abstract: In some examples, a system including a gas turbine engine, the engine including a high-pressure (HP) shaft; HP compressor; HP turbine, second shaft; second compressor; second turbine, the second turbine being coupled to the second compressor via the second shaft (e.g., LP shaft); and a generator coupled to the LP shaft. The generator is configured to generate electrical power from rotation of the LP shaft, and increase electrical power generated by the generator to increase a torque applied to the LP shaft by the generator, e.g., in combination with reduction in engine thrust, or in response to the detection of a stall and/or surge of the engine. The increase in torque applied to the second shaft is configured to increase a rate at which a rotational speed of the second shaft decreases, e.g., in combination with the reduction in engine thrust or during the stall/surge of the engine.

Abstract: An oil pumping system for use with a gas turbine engine includes an electric machine, an oil pump assembly, and a variable frequency drive controller. The variable frequency drive is connected with the electric machine and the oil pump assembly. The variable frequency drive controller is programmed to control a torque and speed of the pump motor independent of the gas turbine engine speed so that a flow of oil moved by the oil pump assembly is controlled to cool or lubricate components of the gas turbine engine independent of the gas turbine engine speed.

Abstract: A redundant oil and fuel pumping system for use with a gas turbine engine. The pumping system includes a plurality of power supplies, a fuel system and an oil system. The fuel system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power supplies. The oil system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power supplies.

Abstract: A redundant oil and fuel pumping system for use with a gas turbine engine. The pumping system includes a plurality of power sources, a fuel system and an oil system. The fuel system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power sources. The oil system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power sources.

Abstract: A redundant oil and fuel pumping system for use with a gas turbine engine. The pumping system includes a plurality of power sources, a fuel system and an oil system. The fuel system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power sources. The oil system pump being driven by electric motors controlled via variable frequency drives powered by the plurality of power sources.

Abstract: An oil pumping system for use with a gas turbine engine includes an electric machine, an oil pump assembly, and a variable frequency drive controller. The variable frequency drive is connected with the electric machine and the oil pump assembly. The variable frequency drive controller is programmed to control a torque and speed of the pump motor independent of the gas turbine engine speed so that a flow of oil moved by the oil pump assembly is controlled to cool or lubricate components of the gas turbine engine independent of the gas turbine engine speed.

Abstract: 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.

Abstract: A sealed cooling system includes a coolant tank having a liquid space configured to hold liquid coolant, and a gas space configured to hold gas. A temperature sensor detects the temperature of the liquid coolant. A pressure sensor detects the pressure in the coolant tank. A processor compares the pressure in the coolant tank to predicted pressure in the coolant tank as a function of liquid coolant temperature. The processor determines and outputs a signal indicative of a leak in the sealed cooling system if the pressure in the coolant tank deviates from the predicted pressure in the coolant tank according to predetermined criteria.

Abstract: A cooling system includes a first cooling loop, a second cooling loop and a heat exchanger configured to transfer heat from the first cooling loop to the second cooling loop. The first cooling loop includes a vapor/liquid separation feature configured to separate vapor present in the first cooling loop due to a leak between the first cooling loop and the second cooling loop. The first cooling loop also includes a pressure sensor configured to detect an increase in pressure in the first cooling loop that may result from a leak of second coolant into the first cooling loop.

Abstract: A cooling system includes a first cooling loop, a second cooling loop and a heat exchanger configured to transfer heat from the first cooling loop to the second cooling loop. The first cooling loop includes a vapor/liquid separation feature configured to separate vapor present in the first cooling loop due to a leak between the first cooling loop and the second cooling loop. The first cooling loop also includes a pressure sensor configured to detect an increase in pressure in the first cooling loop that may result from a leak of second coolant into the first cooling loop.

Abstract: An example method includes obtaining a representation of a change in rotational speed of an electric machine; obtaining a representation of an expected change in rotational speed of the electric machine; and determining, based on the obtained representation of the change in rotational speed of the electric machine and the representation of an expected change in rotational speed of the electric machine, whether a disconnect device has failed, wherein, when operating in an engaged state, the disconnect device is configured to couple rotational mechanical energy between the electric machine and a rotating device, and wherein, when operating in a disengaged state, the disconnect device is not configured to couple rotational mechanical energy between the electric machine and the rotating device.

Abstract: A cooling system includes a first cooling loop, a second cooling loop and a heat exchanger configured to transfer heat from the first cooling loop to the second cooling loop. The first cooling loop includes a flow restrictor, an inertial separator, and a pressure relief valve cooperating to effect diversion of vapor present in the first cooling loop due to a leak between the first cooling loop and the second cooling loop.

Abstract: A sealed cooling system includes a coolant tank having a liquid space configured to hold liquid coolant, and a gas space configured to hold gas. A temperature sensor detects the temperature of the liquid coolant. A pressure sensor detects the pressure in the coolant tank. A processor compares the pressure in the coolant tank to predicted pressure in the coolant tank as a function of liquid coolant temperature. The processor determines and outputs a signal indicative of a leak in the sealed cooling system if the pressure in the coolant tank deviates from the predicted pressure in the coolant tank according to predetermined criteria.