Abstract: An example electric machine includes a rotor and a stator. The stator includes a stator core defining a longitudinal axis and a plurality of stator end windings extending from the stator core along the longitudinal axis. Adjacent end windings of the plurality of stator end windings define a radial gap, and the radial gap is configured to allow a cooling fluid to flow within the radial gap and in contact with the adjacent stator end windings.

Abstract: A stator housing assembly includes a stator housing and a stator sleeve. The stator sleeve including a combination of composite layers with different high strength fibers. The stator housing includes a first end section and a second end section that define a stator cavity configured to contain a pressurized cooling fluid. The stator sleeve defines a longitudinal axis and includes a plurality of layers of composite materials that include more than one high strength fiber material. High strength fibers may include carbon and glass fibers. Portions of the stator sleeve may have different combinations of high strength fiber materials and fiber orientations to optimize sleeve properties.

Abstract: An example propulsion engine includes at least one radial support structure (RSS) radially disposed about an engine centerline. A power cable is at least partially contained within a cavity of a first RSS or a cavity fluidically coupled to the cavity of the first RSS. The first RSS defines at least one cooling aperture fluidically coupling the cavity of the first RSS to an exterior surface of the first RSS. The at least one cooling aperture is configured to allow cooling fluid to flow into or out of the cavity of the first RSS to cool the power cable.

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 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 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: 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.