Hybrid-electric aircraft engines

Abstract

A method for operating a hybrid electric propulsion system for an aircraft, the hybrid electric propulsion system comprising a turbine, an electric motor coupled to the turbine, and a propeller coupled to the turbine, the method comprising: operating the turbine to drive the propeller; receiving data indicating a failure condition of the hybrid electric propulsion system; and in response to receiving the data indicating the failure condition, extracting power from the turbine using the electric motor to slow one or more rotating components of the turbine.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a non-provisional application, which claims the benefit of priority under 35 USC § 119(e) to U.S. Provisional Application No. 63 / 072,542, filed on August 31, 2020, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present subject matter generally relates to a hybrid-electric propulsion engine for an aircraft, and a method for operating a hybrid-electric propulsion engine to reduce the risk of damage during a failure scenario. Background Art

[0004] Some aircraft generally include a gas turbine engine to provide propulsion to the aircraft. In addition to the low-pressure system, the turbine of such a gas turbine engine may include a high-pressure system or core. Depending on the type of gas turbine engine, the low-pressure shaft of the low-pressure system may be mechanically coupled to, for example, a fan or propeller.

[0005] During the failure event of the engine, the low-pressure system and high-pressure system of the gas turbine engine may exceed the desired threshold. For example, in order to ensure that the low-pressure system does not fail in such a failure situation, the low-pressure system is designed to receive the residual energy from the core, and more particularly, the turbine of the low-pressure system is designed to rotate at a higher rotation speed than originally required. However, this may result in a relatively heavy, large and expensive low-pressure system, or more particularly, a relatively large hole in the turbine of the low-pressure system. Therefore, a gas turbine engine that can solve these problems in an improved manner will be welcomed. Summary of the invention

[0006] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0007] In one exemplary aspect of the present disclosure, a method for operating a hybrid electric propulsion system for an aircraft is provided, the hybrid electric propulsion system comprising a turbine, an electric motor coupled to the turbine, and a propeller coupled to the turbine. The method comprises: operating the turbine to drive the propeller; receiving data indicating a failure condition of the hybrid electric propulsion system; and in response to receiving the data indicating the failure condition, extracting power from the turbine using the electric motor to slow down one or more rotating components of the turbine.

[0008] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A complete and open disclosure of the invention, including the best mode thereof, is set forth in the specification, which makes reference to the accompanying drawings, in which:

[0010] Figure 1 is a schematic cross-sectional view of a gas turbine engine incorporated into a hybrid electric propulsion system according to an exemplary embodiment of the present disclosure.

[0011] Figure 2 is a flow chart depicting a method for operating a hybrid electric propulsion system according to an exemplary aspect of the present disclosure. DETAILED DESCRIPTION

[0012] Reference will now be made in detail to the present embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Similar or similar designations in the drawings and description are used to refer to similar or similar parts of the present invention.

[0013] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0014] As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component.

[0015] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle, and refer to the normal operating attitude of the gas turbine engine or vehicle. For example, for a gas turbine engine, front refers to a position closer to the engine inlet, and rear refers to a position closer to the engine nozzle or exhaust.

[0016] The terms "upstream" and "downstream" refer to relative directions with respect to the flow of a fluid in a fluid path. For example, "upstream" refers to the direction in which the fluid is flowing out, and "downstream" refers to the direction in which the fluid is flowing.

[0017] The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate components or features, unless otherwise indicated herein.

[0018] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0019] As used throughout the specification and claims, approximate language is used to modify any quantitative representation, and the quantitative representation can be allowed to change without causing the basic function associated therewith to change. Therefore, the value modified by one or more terms such as "about", "approximately" and "substantially" is not limited to the specified exact value. In at least some cases, approximate language may correspond to the accuracy of the instrument used to measure the value, or the accuracy of the method or machine used to configure or manufacture parts and / or systems. For example, approximate language may refer to within a margin of 1%, 2%, 4%, 10%, 15% or 20%. These approximate margins can be applied to a single value, any one or two endpoints that limit the range of values, and / or the margin of the range between the endpoints.

[0020] Here and throughout the specification and claims, range limitations are combinable and interchangeable, such that ranges are identified and include all subranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein include the endpoints, and the endpoints are independently combinable with each other.

[0021] The present disclosure generally relates to a hybrid electric propulsion system and a method for operating the same so as to prevent or minimize the risk of overspeeding of a low-pressure turbine of a gas turbine engine in the event of a failure of the hybrid electric propulsion system. The hybrid electric propulsion system generally includes a gas turbine engine, an electric motor coupled to the gas turbine engine, and a propeller also coupled to the gas turbine engine. For example, in certain exemplary aspects, the hybrid electric propulsion system may be incorporated into, for example, an aircraft, and the gas turbine engine and the propeller may be, for example, a turbofan engine. The electric motor may be coupled to the low-pressure system of the gas turbine engine. In the event of a failure situation (such as a load loss situation), the electric motor may be used to extract power from the low-pressure system, acting as a drag on the low-pressure system, to reduce the amount of energy within the low-pressure system of the turboshaft engine.

[0022] Depending on the type and / or extent of the failure, the electric machine may draw a maximum amount of power, or alternatively may draw less than a maximum amount of power.

[0023] Reference now Figure 1 , a cross-sectional view of an exemplary embodiment of a gas turbine engine as may be incorporated with one or more inventive aspects of the present disclosure is provided. In particular, Figure 1 The exemplary gas turbine engine of FIG. 1 is configured as a single unducted rotor engine 10 defining an axial direction A, a radial direction R, and a circumferential direction C. As shown in FIG. Figure 1As seen, the engine 10 is in the form of an open rotor propulsion system and has a rotor assembly 12 that includes an array of airfoils arranged about a central longitudinal axis 14 of the engine 10, and more particularly includes an array of rotor blades 16 arranged about the central longitudinal axis 14 of the engine 10. In addition, as will be explained in more detail below, the engine 10 additionally includes a non-rotating vane assembly 18 (i.e., non-rotating relative to the central axis 14) positioned behind the rotor assembly 12, which includes an array of airfoils also arranged about the central axis 14, and more particularly includes an array of vanes 20 arranged about the central axis 14. The rotor blades 16 are arranged in a typically equidistant relationship about the centerline 14, and each blade has a root 22 and a tip 24 and a span defined therebetween. Similarly, the vanes 20 are also arranged in a typically equidistant relationship about the centerline 14, and each has a root 26 and a tip 28 and a span defined therebetween. The rotor assembly 12 further includes a hub 44 located forward of the plurality of rotor blades 16.

[0024] In addition, the engine 10 includes a turbine 30 having a core (or high pressure / high speed system) 32 and a low pressure / low speed system. It will be understood that, as used herein, the terms "speed" and "pressure" are used interchangeably in conjunction with the high pressure / high speed system and the low pressure / low speed system. Furthermore, it will be understood that the terms "high" and "low" are used in this same context to distinguish between the two systems and are not meant to imply any absolute speed and / or pressure values.

[0025] The core 32 generally includes a high-speed compressor 34, a high-speed turbine 36, and a high-speed shaft 38 extending therebetween and connecting the high-speed compressor 34 and the high-speed turbine 36. The high-speed compressor 34, the high-speed turbine 36, and the high-speed shaft 38 may be collectively referred to as the high-speed rotating shaft of the engine. In addition, a combustion section 40 is located between the high-speed compressor 34 and the high-speed turbine 36. The combustion section 40 may include one or more configurations for receiving a mixture of fuel and air and providing a flow of combustion gases through the high-speed turbine 36 for driving the high-speed rotating shaft.

[0026] Additionally, for the exemplary engine 10 depicted, the aircraft and / or engine 10 includes a fuel delivery system 66. The fuel delivery system 66 generally includes a fuel source 68 (which may be, for example, a fuel tank of an aircraft including the engine 10), one or more fuel lines 70 extending between the fuel source 68 and the combustion section 40 of the engine 10, and a fuel valve 72. The fuel valve 72 is in fluid communication with the one or more fuel lines 70 and is configured to regulate the flow of fuel from the fuel source 68 through the one or more fuel lines 70 to the combustion section 40. The fuel valve 72 may be referred to as a fuel metering unit ("FMU") and may generally control the power output of the engine 10.

[0027] Still reference Figure 1 , the low speed system additionally includes a low speed turbine 42, a low speed compressor or supercharger 44, and a low speed shaft 46 extending between and connecting the low speed compressor 44 and the low speed turbine 42. The low speed compressor 44, the low speed turbine 42, and the low speed shaft 46 may be collectively referred to as the low speed rotating shaft 55 of the engine.

[0028] Although engine 10 is depicted with low-speed compressor 44 positioned forward of high-speed compressor 34, in certain embodiments, compressors 34, 44 may be arranged in a staggered arrangement. Additionally or alternatively, although engine 10 is depicted with high-speed turbine 36 positioned forward of low-speed turbine 42, in certain embodiments, turbines 36, 42 may similarly be arranged in a staggered arrangement.

[0029] Still reference Figure 1 , the turbine 30 is generally enclosed in a cowling 48. Further, it will be appreciated that the cowling 48 at least partially defines an inlet 50 and an exhaust port 52, and includes a turbine flow path 54 extending therebetween. For the illustrated embodiment, the inlet 50 is an annular or axisymmetric 360 degree inlet 50 located between the rotor blade assembly 12 and the fixed or stationary vane assembly 18, and provides a path for the incoming atmosphere to enter the turbine flow path 54 (and the compressor 44, 34, the combustion section 40, and the turbine 36, 42) inboard of the guide vanes 28 along a radial direction R. Such a location may be advantageous for a variety of reasons, including management of icing performance and protection of the inlet 50 from various objects and materials such as may be encountered in operation.

[0030] However, in other embodiments, the inlet 50 may be positioned in a non-axisymmetric arrangement at any other suitable location, such as rearward of the vane assembly 18 , etc.

[0031] In addition, if Figure 1 As schematically depicted by dashed lines in FIG, engine 10 may include a duct extending from the compressor section to an outlet in cowling 48. The duct may extend from compressors 44, 34 or from a location between compressors 44, 34.

[0032] As depicted, rotor assembly 12 is driven by turbine 30, and more particularly by low speed shaft 55. More particularly, Figure 1The engine 10 in the embodiment shown in FIG. 1 also includes a power gearbox 56, and the rotor assembly 12 is driven across the power gearbox 56 by the low speed shaft 55 of the turbine 30. In this way, the rotating rotor blades 16 of the rotor assembly 12 can rotate about the axis 14 and generate thrust to propel the engine 10 in the forward direction F, and thus propel the aircraft associated with the engine 10. For example, in some embodiments, the rotor assembly 12 can be driven by a rotor blade 16 similar to the rotor assembly 16. Figure 1 One or more engines configured in the manner depicted in the exemplary engine 10 may be incorporated into Figure 1 in and for use with aircraft.

[0033] The power gearbox 56 may include a gear set for reducing the rotational speed of the low speed shaft 55 relative to the low speed turbine 42 so that the rotor assembly 12 may rotate at a lower rotational speed than the low speed shaft 55 .

[0034] As briefly mentioned above, the engine 10 includes a vane assembly 18. The vane assembly 18 extends from the cowling 48 and is positioned rearwardly of the rotor assembly 12. The vanes 20 of the vane assembly 18 may be mounted to a fixed frame or other mounting structure and do not rotate relative to the central axis 14. For reference purposes, Figure 1 The forward direction is also depicted by arrow F, which in turn defines the front and rear of the system. Figure 1 As shown in FIG, the rotor assembly 12 is located in front of the turbine 30 in a "pull-in" configuration, and the exhaust port 52 is located behind the guide vanes 28. As will be appreciated, the vanes 20 of the vane assembly 18 may be configured to straighten the airflow from the rotor assembly 12 (e.g., reduce swirl in the airflow) to improve the efficiency of the engine 10. For example, the vanes 20 may be sized, shaped, and configured to impart a reactionary swirl to the airflow from the rotor blades 16 such that in the downstream direction behind the two rows of airfoils (e.g., blades 16, vanes 20), the airflow has a greatly reduced degree of swirl, which may translate into an improved level of induced efficiency.

[0035] Still reference Figure 1 It may be desirable to incorporate a pitch change mechanism into the rotor blades 16, the vanes 20, or both so that the airfoils (e.g., blades 16, vanes 20, etc.) may be rotated independently or in conjunction with one another relative to the pitch axis of rotation. Such pitch changes may be used to change thrust and / or vortex effects in various operating situations, including adjusting the magnitude or direction of thrust generated at the rotor blades 16, or providing a thrust reversal feature that may be useful in certain operating situations (such as when landing an aircraft), or desirably adjusting acoustic noise generated at least in part by the rotor blades 16, the vanes 20, or from the aerodynamic interaction of the rotor blades 16 relative to the vanes 20. More particularly, for Figure 1In the embodiment of the present invention, rotor assembly 12 is depicted as having a pitch change mechanism 58 for rotating rotor blades 16 about their respective pitch axes 60, and vane assembly 18 is depicted as having a pitch change mechanism 62 for rotating vanes 20 about their respective pitch axes 64.

[0036] However, it will be understood that Figure 1 The exemplary single-rotor unducted engine depicted in FIG. 1 is by way of example only, and in other exemplary embodiments, the engine 10 may have any other suitable configuration, including, for example, any other suitable number of shafts or rotating shafts, turbines, compressors, etc.; fixed pitch blades 16, 20, or both; a direct drive configuration (i.e., the gearbox 56 may not be included); etc. Additionally or alternatively, in other exemplary embodiments, any other suitable gas turbine engine may be provided. For example, in other exemplary embodiments, the gas turbine engine may be a ducted turbofan engine, a turboshaft engine, a turboprop engine, a turbojet engine, etc. Furthermore, although the engine 10 is depicted as a single unducted rotor engine, in other embodiments, the engine may include a multi-stage open rotor configuration, and the disclosed aspects described below may be incorporated therein.

[0037] Still reference Figure 1 It will be further understood that the engine 10 is integrated with an electric power system 100 of a hybrid electric propulsion system. The electric power system 100 generally includes an electric machine 102 coupled to at least one of a high voltage system (or core 32) or a low voltage system, an energy storage unit 104, and an electric power bus 108 electrically connecting the various components of the electric power system 100. The electric power bus 108 may be, for example, one or more electrical wires arranged in any suitable configuration.

[0038] Although not shown, the electric power bus 108 may further connect various components of the electric power system 100 to external electric power sources (e.g., other engines with electric motors, additional power storage units, auxiliary power units, etc.) and / or additional power sinks (e.g., other engines with electric motors, aircraft loads, auxiliary engine systems, power resistor groups, additional power storage units, etc.).

[0039] Furthermore, for the illustrated embodiment, the electric machine 102 of the electric power system 100 is also an LP electric machine 102A coupled to the low pressure system of the engine 10. More specifically, for the illustrated embodiment, the LP electric machine 102A is embedded within the engine 10, at a location within or behind the turbine section of the engine 10, and inboard of the core airflow path 54 through the engine 10 along the radial direction R. This configuration may help reduce the rotational speed of the low pressure system during a shear event of the low pressure shaft 46, as will be understood from the following description.

[0040] However, it will be appreciated that in other example embodiments, the LP motor 102A may additionally or alternatively be configured in any other suitable manner. For example, in other embodiments, the LP motor 102A may be embedded within a compressor section of the engine 10, may be located outside of the core airflow path 54 along the radial direction R (and, for example, within the cowling 48), etc.

[0041] Furthermore, for the illustrated embodiment, the LP motor 102A is not the only motor 102 of the electric power system 100. More specifically, the electric power system 100 further includes an HP motor 102B coupled to the high pressure system / core of the engine 10 and in electrical communication with the electric power bus 108. For the illustrated embodiment, the HP motor 102B is positioned at a location outside the core airflow path 54 along the radial direction R, driven by the gear connection 106. For example, in certain embodiments, the HP motor 102B may be coupled to an auxiliary gearbox (not shown), which in turn is coupled to the high pressure system of the engine 10. Additionally, for the illustrated embodiment, the HP motor 102B is located near the compressor section of the engine 10. It will be appreciated that in other embodiments, the HP motor 102B may alternatively be positioned inside the core airflow path 54 along the radial direction R, within the compressor section, or within the turbine section.

[0042] In addition, the LP motor 102A and the HP motor 102B may be relatively powerful motors. For example, in certain exemplary embodiments, the LP motor 102A and the HP motor 102B may each define a maximum power extraction capacity (i.e., a maximum amount of power that the respective motor can generate) of at least about twenty kilowatts of electrical power. For example, in certain exemplary embodiments, the LP motor 102A and the HP motor 102B may define a maximum power extraction capacity of at least about fifty kilowatts of electrical power, such as at least about one hundred kilowatts of electrical power, such as up to about one thousand kilowatts of electrical power. In this way, the LP motor 102A and the HP motor 102B may be able to extract relatively large amounts of energy from the engine 10, and / or may be able to provide large amounts of energy to the engine 10.

[0043] However, it will be appreciated that in other embodiments, one of the LP motor 102A and the HP motor 102B may define a greater maximum power extraction capacity than the other. For example, in certain exemplary embodiments, the LP motor 102A may define a maximum power extraction capacity that is at least about 10% greater than the HP motor 102B, such as at least about 15% greater, such as at least about 25% greater, such as at least about 50% greater, such as up to 1000% greater. In this manner, the engine 10 may be able to extract a greater amount of energy from the low pressure system (which may be coupled to the rotor assembly 12 in the absence of a shaft failure) when the engine is operated according to one or more exemplary aspects of the method 200 described below.

[0044] Still reference Figure 1 In at least some exemplary embodiments, the energy storage unit 104 may include one or more batteries or battery packs. Additionally or alternatively, the energy storage unit 104 may include one or more supercapacitor arrays, one or more ultracapacitor arrays, or both.

[0045] In at least some embodiments, the energy storage unit 104 may be configured to hold at least about twenty kilowatt-hours of electrical power. For example, in certain exemplary embodiments, the energy storage unit 104 may be configured to store at least about thirty kilowatt-hours of electrical power, such as at least about fifty kilowatt-hours of electrical power, such as at least about sixty kilowatt-hours of electrical power, such as up to about one thousand kilowatt-hours of electrical power. In this way, when the engine is operated according to one or more exemplary aspects of the method 200 described below, the energy storage unit 104 may be able to receive a relatively large amount of energy from the engine 10 over an extended period of time.

[0046] However, it will be understood that the exemplary electric power system 100 described herein is by way of example only. In other exemplary embodiments, the electric power system 100 may not include both the LP motor 102A and the HP motor 102B, but may include only one of the LP motor 102A and the HP motor 102B. Additionally or alternatively, the electric power system 100 may have any other suitable power absorber.

[0047] As will be referred to below Figure 2 As discussed in more detail, Figure 1The exemplary electric power system 100 depicted in FIG. 1 may be used as an overspeed protection system for the engine 10. For example, in the event of a failure scenario of a hybrid electric propulsion system, such as the exemplary engine 10 depicted, the electric power system 100 may be used to slow down the low pressure system, and more specifically the low pressure turbine 42 of the low pressure system, by operating the LP electric machine 102A as a generator, extracting power from the low pressure system. In this manner, the electric power system 100 may help prevent the low pressure turbine 42 from rotating at a speed that exceeds an upper limit of the rotational speed of the low pressure turbine 42. The upper limit of the rotational speed of the low pressure turbine 42 may be, for example, a rotor disk rupture speed.

[0048] Furthermore, by utilizing such a system, the low pressure turbine 42 may be designed to withstand lower rotational speeds than would otherwise be necessary because the LP machine 102A may prevent the low pressure turbine 42 from reaching a higher terminal speed. Thus, this may allow the low pressure turbine 42 (such as the rotor disks and bores of the low pressure turbine 42) to be designed smaller and lighter, resulting in a lighter and less expensive engine.

[0049] Additionally, assuming that the exemplary electric power system includes an HP motor 102B coupled to the high pressure system, the electric power system 100 can further help slow down the high pressure system by similarly extracting power from the high pressure system using the HP motor 102B. This can reduce the amount of energy that the low pressure turbine 42 must absorb during certain failure scenarios, thereby allowing further reductions in the size of certain components of the low pressure turbine 42.

[0050] Depending on where the failure is located, the system may or may not immediately reduce fuel flow to the combustion section 40. For example, if the failure is in the high pressure system (such as, for example, high pressure variable guide vanes, fuel valves, etc.), fuel flow may be immediately reduced to prevent or reduce the high pressure system from accelerating faster than the low pressure system. However, in contrast, if the failure is in the low pressure system (such as, for example, low pressure shaft shear), the low pressure system may accelerate faster than the high pressure system (potentially creating an undesirably high rotational speed condition in the low pressure system), and power may be increased to the high pressure system (e.g., by additional fuel flow, increased power to the motor 102B, etc.) to increase the speed of the high pressure system to trigger an overspeed condition of the engine.

[0051] Still reference Figure 1 , the exemplary electric power system 100 is operably connected to a controller 116. The controller 116 may be an engine controller for the engine 10 (e.g., a full authority digital engine control controller), an aircraft controller, a controller dedicated to the electric power system 100, or the like.

[0052] Controller 116 may be configured to receive data indicating various operating conditions and parameters of engine 10 during operation of engine 10. For example, Figure 1 As understood in , engine 10 includes one or more sensors 114 that are configured to sense data indicative of various operating conditions and parameters of engine 10 , such as rotational speed, temperature, pressure, vibration, etc. For example, in the illustrated embodiment, the one or more sensors 114 include: a first speed sensor 114A, which is configured to sense data indicating the rotational speed of the rotor assembly 12; a second sensor 114B, which is configured to sense data indicating the high pressure system (such as the rotational speed of the high pressure spool 38, the compressor outlet temperature, etc.); a third sensor 114C, which is configured to sense data indicating one or more combustion section parameters (such as the temperature within the combustion section 40, the fuel flow to the combustion section 40, one or more pressures within or around the combustion section 40, etc.), one or more high pressure turbine parameters (such as the turbine inlet temperature, the rotational speed of the high pressure turbine 36, etc.), or both; a fourth sensor 114D, which is operable to sense data indicating one or more parameters of the low pressure system (such as the rotational speed of the low pressure spool 55); and a fifth sensor 114E, which is configured to sense data indicating the position of one or more variable geometry components (such as one or more variable inlet guide vanes, outlet guide vanes, rotor blades 16, guide vanes 20, etc.).

[0053] With particular reference to the operation of the controller 116, in at least some embodiments, the controller 116 may include one or more computing devices 118. The computing device 118 may include one or more processors 118A and one or more memory devices 118B. The one or more processors 118A may include any suitable processing device, such as a microprocessor, a microcontroller, an integrated circuit, a logic device, and / or other suitable processing device. The one or more memory devices 118B may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, a hard drive, a flash drive, and / or other memory devices.

[0054] One or more memory devices 118B may store information that can be accessed by one or more processors 118A, including computer-readable instructions 118C that can be executed by one or more processors 118A. Instructions 118C may be any set of instructions that, when executed by one or more processors 118A, cause one or more processors 118A to perform operations. In some embodiments, instructions 118C may be executed by one or more processors 118A to cause one or more processors 118A to perform operations, such as any operations and functions that controller 116 and / or computing device 118 are configured for, as described herein for operating engine 10, electric power system 100 and / or hybrid electric propulsion system operations (e.g., method 200), and / or any other operations or functions of one or more computing devices 118. Instructions 118C may be software written in any suitable programming language, or may be implemented in hardware. Additionally and / or alternatively, instructions 118C may be executed in logically and / or virtually separate threads on processor 118A. Memory device 118B may further store data 118D that can be accessed by processor 118A. For example, data 118D may include data indicative of power flow, data indicative of engine 10 / aircraft operating conditions, and / or any other data and / or information described herein.

[0055] The computing device 118 may also include a network interface 118E for communicating, for example, with other components of the engine 10, an aircraft incorporating the engine 10, the electric power system 100, and the like. For example, in the depicted embodiment, as described above, the engine 10 includes one or more sensors 114 for sensing data indicative of one or more parameters of the engine 10 and various ancillary systems, and the electric power system 100 includes an energy storage unit 104, an LP motor 102A, and an HP motor 102B. The controller 116 is operably coupled to these components via, for example, the network interface 118E, such that the controller 116 may receive data indicative of various operating parameters sensed by the one or more sensors 114 during operation, various operating conditions of the components, and the like, and may further provide commands to control the current of the electric power system 100 and other operating parameters of these systems, for example, in response to the data sensed by the one or more sensors 114 and other conditions.

[0056] The network interface 118E may include any suitable components for interfacing with one or more networks, including, for example, transmitters, receivers, ports, controllers, antennas, and / or other suitable components. For example, in the illustrated embodiment, the network interface 118E is configured to communicate wirelessly with these components via a wireless communication network (e.g., a wireless communication network provided by a wireless communication network such as ... Figure 1 The communication is shown by the dotted line in the figure).

[0057] The technology discussed herein refers to computer-based systems and actions taken by computer-based systems and information sent to and from computer-based systems. It will be appreciated by those of ordinary skill in the art that the inherent flexibility of computer-based systems allows for various possible configurations, combinations, and divisions of tasks and functions between and within components. For example, the processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memories, instructions, and applications can be implemented on a single system or distributed on multiple systems. Distributed components can operate sequentially or in parallel.

[0058] Reference now Figure 2 , a flow chart of a method 200 for operating a hybrid electric propulsion system of an aircraft is provided. The method 200 may be similar to the method described above with reference to Figure 1 One or more of the described exemplary embodiments and / or for use with one or more of the other exemplary embodiments described herein.For example, in at least some exemplary aspects, a hybrid electric propulsion system may include a turbine, an electric machine coupled to the turbine, and a propeller coupled to the turbine.

[0059] The method 200 includes operating a turbine to drive a propeller at (202) and receiving data indicative of a failure condition of a hybrid-electric propulsion system at (204). Receiving data at (204) may include receiving data from one or more sensors configured to sense data indicative of one or more operating conditions and / or parameters of the turbine and the hybrid-electric propulsion system using a controller.

[0060] In certain example embodiments, the failure condition may be a shaft shear failure. In this case, receiving data at (204) may include receiving data indicating that the rotational speed of the LP turbine of the low pressure system of the turbine is different from the rotational speed of the LP compressor of the low pressure system. Additionally or alternatively, in this case, receiving data at (204) may include receiving data indicating that one or more components at a position downstream of the combustion section exceed acceleration and / or speed limits (e.g., data indicating that the LP turbine is approaching or exceeding an upper limit of a rotational speed parameter or a predetermined buffer threshold to an upper limit of a rotational speed parameter). The speed parameter may be an angular velocity, an angular acceleration, etc. Additionally or also alternatively, in this case, receiving data at (204) may include receiving data indicating that one or more components at a position upstream of the combustion section exceed a deceleration threshold of one or more rotating components. Additionally or also alternatively, in this case, receiving data at (204) may include receiving data indicating that the compressor outlet pressure drops below a minimum threshold, or data indicating a rapid change in turbine clearance if the engine includes turbine clearance sensing.

[0061] In other exemplary embodiments, the failure condition may be a fuel flow valve failure. In this case, receiving data at (204) may include receiving data indicating a difference between a selected valve position and an actual valve position, data indicating an acceleration above an estimated amount or threshold on the low pressure system and / or on the high pressure system, data indicating that a speed of the low pressure system or the high pressure system exceeds or approaches an upper rotational speed parameter limit and / or a predetermined buffer threshold to a corresponding upper rotational speed parameter limit, or data indicating a rapid change in turbine clearance if the engine includes turbine clearance sensing.

[0062] In other exemplary embodiments, the failure condition may be a variable geometry component failure. In such cases, receiving data at (204) may include receiving data indicating a difference between a selected position and an actual position, data indicating an increased acceleration above a threshold on the low pressure system and / or the high pressure system, data indicating a speed parameter of the low pressure system or the high pressure system exceeds or approaches an upper rotational speed parameter limit and / or a predetermined buffer threshold to a respective upper rotational speed parameter limit, or data indicating a rapid change in turbine clearance if the engine includes turbine clearance sensing.

[0063] In still further other exemplary embodiments, the failure condition may be any other failure that affects the rotational speed of the turbine. For example, the failure condition may be a gearbox failure. Additionally or alternatively, the failure condition may be an external load loss condition. For example, method 200 may include extracting power from the engine at (203) using a motor that can rotate with the high pressure system of the engine, the low pressure system of the engine, or both. With respect to such exemplary aspects, the failure condition may be an unexpected or unplanned reduction in the amount of power extracted, potentially resulting in an undesired acceleration of the engine. For example, method 200 may include extracting at least about 10 kilowatts (kw) of power at (203), such as at least 15kw, such as at least 20kw, such as at least 25kw, such as at least 50kw, and up to 1000kw. The failure condition may be an unexpected or unplanned reduction of at least 50% of the amount of power extracted, an unexpected or unplanned reduction of at least 60%, such as at least 70%, such as at least 80%, such as at least 90% of the amount of power extracted. Furthermore, with respect to such configurations, the data received at (204) may include data indicating a reduction in the external load, or data indicating that a reduction in the external load is likely to occur.

[0064] Still reference Figure 2For the exemplary aspect depicted, method 200 includes reducing fuel flow to a combustion section of the turbine at (206) in response to receiving data indicating a failure condition at (204). In particular, for the exemplary aspect depicted, reducing fuel flow to the combustion section at (206) includes terminating fuel flow to the combustion section of the turbine at (208). Additionally, reducing fuel flow to the combustion section at (206) may include reducing fuel flow using a fuel metering unit, a fuel shutoff valve, or a combination thereof.

[0065] More specifically, it will be appreciated that in at least some exemplary aspects, method 200 may reduce fuel flow at (206) based on the type of failure condition. For example, in some exemplary aspects, the data received at (204) may indicate a failure condition within or directly affecting the high pressure system (such as HP variable guide vane failure, fuel valve failure, HP shaft shear, etc.). With respect to such exemplary aspects, method 200 may include reducing fuel flow to the combustion section in response to receiving data indicating a failure condition within or directly affecting the high pressure system.

[0066] However, in other exemplary aspects, the method may not reduce fuel flow at (206). For example, in certain exemplary embodiments, the engine may include one or more overspeed safety measures triggered by an overspeed monitor of the high pressure system. In this case, when the data received at (204) indicates a failure situation within the low pressure system or directly affecting the low pressure system (such as low pressure shaft shear, LP variable guide vane failure, etc.), the method may encourage the high pressure system to accelerate to trigger the overspeed safety measure. In this case, the method 200 may include maintaining fuel flow to the engine in response to receiving data indicating an LP system failure situation at (209), increasing power to the high pressure system in response to receiving data indicating an LP system failure situation, or both. For example, the method may increase fuel flow to the combustion section of the turbine in response to receiving data indicating an LP system failure situation, may increase power to an electric machine capable of rotating with the high pressure system, or both.

[0067] Furthermore, for the exemplary aspect depicted, method 200 includes, at (210), extracting power from the turbine using the electric machine to slow one or more rotating components of the turbine in response to receiving data indicating a failure condition at (204). In particular, for the exemplary aspect depicted, extracting power from the turbine using the electric machine at (210) includes extracting power from the turbine using the electric machine at (212) substantially simultaneously with reducing fuel flow to a combustion section of the turbine at (206).

[0068] It will be understood that, as used herein, the term "substantially simultaneously" refers to two events occurring at least in part within a relatively small time frame. For example, substantially simultaneously may refer to two events occurring at least in part within a ten second window (such as within an eight second window, such as within a five second window, such as within a two second window).

[0069] Furthermore, for the exemplary aspect depicted, it will be appreciated that the turbine includes a high pressure turbine and a low pressure turbine, and that the electric machine and the propeller are each coupled to the low pressure turbine. Thus, for this exemplary aspect of method 200, it will be appreciated that extracting power from the turbine using the electric machine at (210) includes reducing the rotational speed of the low pressure turbine at (214).

[0070] However, it will be further understood that for the exemplary aspects depicted, the hybrid electric propulsion system may further include one or more additional electric machines. For example, the electric machine may be a first electric machine coupled to the low pressure turbine, and the hybrid electric propulsion system may further include a second electric machine coupled to the high pressure turbine of the high pressure system. With respect to such exemplary aspects, it will be understood that extracting power from the turbine using the electric machine at (210) may further include extracting power from the low pressure turbine using the first electric machine at (216), and extracting power from the high pressure turbine using the second electric machine at (217).

[0071] Extracting power from the high pressure system at (217) may create drag on the high pressure system and may therefore help reduce the chance of the low pressure turbine overspeeding.

[0072] Notably, for exemplary aspects having a first electric machine and a second electric machine coupled to a low-pressure turbine and a high-pressure turbine, it may be beneficial to change the ratio of the amount of electrical power extracted from the low-pressure system / low-pressure turbine to the amount of electrical power extracted from the high-pressure system / high-pressure turbine. For example, in certain exemplary aspects, receiving data indicating a failure scenario at (204) may include receiving data indicating a type of failure scenario, an extent of the failure scenario, or both, and extracting power from the turbine using the electric machine at (210) may include changing the ratio of the amount of power extracted from the low-pressure system using the first electric machine to the amount of power extracted from the high-pressure system using the second electric machine based at least in part on the type of failure scenario, the extent of the failure scenario, or both.

[0073] Additionally or alternatively, method 200 may include changing the ratio of the amount of power extracted from the low pressure system to the amount of power extracted from the high pressure system based on other data received at (204). For example, in certain example aspects, method 200 may include changing the ratio of the amount of power extracted from the low pressure system to the amount of power extracted from the high pressure system based on one or more of a rotational speed parameter of the high pressure turbine, a rotational speed parameter of the low pressure turbine, a margin of the rotational speed parameter of the high pressure turbine to an upper limit of the rotational speed parameter of the high pressure turbine, a margin of the rotational speed parameter of the low pressure turbine to an upper limit of the rotational speed parameter of the low pressure turbine, etc.

[0074] However, it will be appreciated that the above exemplary aspects are provided merely as examples, and in other exemplary aspects, method 200 may include only extracting electrical power from a single electric machine.

[0075] Still reference Figure 2 2, it will be appreciated that in certain failure scenarios (and based on the extent of the failure), it may not be necessary to apply full speed reduction measures. For example, where the failure scenario is a variable geometry failure scenario, it may not be necessary to completely terminate fuel flow to the combustion section of the gas turbine engine, nor is it necessary to use an electric machine to extract the maximum amount of power from, for example, a low pressure system.

[0076] Therefore, still refer to Figure 2 , for an exemplary aspect of the depicted method 200, extracting power from the turbine at (210) further includes determining a desired speed reduction of one or more rotating components of the turbine at (218), and extracting an amount of power from the turbine using an electric machine based on the desired speed reduction at (220).

[0077] In certain exemplary aspects, determining the desired speed reduction of one or more rotating components of the turbine at (218) includes determining a margin between a rotational speed parameter of the one or more rotating components and an upper rotational speed parameter limit of one or more rotating events at (222). For example, in certain exemplary embodiments, the rotational speed parameter may be a rotational speed, a rotational acceleration, or a combination thereof.

[0078] In a further exemplary aspect, extracting an amount of power from the turbine using the electric machine based on the determined desired amount of speed reduction at (220) may include extracting an amount of power less than a maximum power extraction capacity of the electric machine using the electric machine at (224). For example, extracting an amount of power less than a maximum power extraction capacity of the electric machine using the electric machine at (224) may include extracting an amount of power equal to 90% or less of the maximum power extraction capacity of the electric machine (such as equal to 80% or less of the maximum power extraction capacity of the electric machine, such as equal to 70% or less of the maximum power extraction capacity of the electric machine) and at least about 15% of the maximum power extraction capacity of the electric machine using the electric machine.

[0079] Furthermore, still in such a configuration, the extraction of power from the turbine at (210) may be controlled as a feedback loop. In particular, it will be appreciated that in at least certain exemplary aspects, determining the desired speed reduction of one or more components at (218) may include continuously determining the desired speed reduction of the one or more components, and extracting an amount of power from the turbine using the electric motor at (220) may include modifying the amount of power extracted from the turbine using the electric motor based on the updated determined desired speed reduction of one or more rotating components of the turbine. This is accomplished by Figure 2 As depicted by arrow 225 .

[0080] In each of the above exemplary aspects, it will be understood that the hybrid electric propulsion system further includes an electrical energy sink. The electrical energy sink may be one or more of an electrical energy storage unit, an electrical energy resistor bank, an aircraft electrical bus, one or more electric machines coupled to other engines of the aircraft, etc. In this case, it will be understood that method 200 further includes providing electrical power from the electric machine to the electrical energy sink at (226).

[0081] Furthermore, in certain exemplary aspects, the energy absorber may not be an energy absorber external to the engine. For example, when the failure condition is a low-pressure failure, the energy absorber may be the high-pressure system (or more specifically, an electric motor coupled to the high-pressure system). With respect to this configuration, providing electrical power from the electric motor to the electrical energy absorber at (226) may include providing electrical power from the electric motor coupled to the low-pressure system to a separate electric motor coupled to the high-pressure system at (227).

[0082] Operation of a hybrid electric propulsion system according to the present disclosure may allow one or more electric machines to effectively reduce the terminal speed reached by the low pressure system and / or the high pressure system during a failure scenario of the engine. In this manner, it will be appreciated that certain components of the engine may be redesigned to instead withstand the lower terminal speeds of these components. For example, with respect to the low pressure turbine, the various rotor disks included therein may be designed to be smaller and lighter, since the design goal is to be able to withstand the lower terminal speed in the event of a failure scenario. This may result in a lighter, more cost-effective, and more fuel-efficient engine.

[0083] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined method. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. These other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that have insubstantial differences from the literal language of the claims.

[0084] Further embodiments of the present disclosure may be disclosed in the following clauses:

[0085] A method for operating a hybrid electric propulsion system for an aircraft, the hybrid electric propulsion system comprising a turbine, an electric motor coupled to the turbine, and a propeller coupled to the turbine, the method comprising: operating the turbine to drive the propeller; receiving data indicating a failure condition of the hybrid electric propulsion system; and in response to receiving the data indicating the failure condition, extracting power from the turbine using the electric motor to slow one or more rotating components of the turbine.

[0086] A method according to one or more of these clauses, wherein extracting power from a turbine using an electric motor to slow one or more rotating components of the turbine comprises: determining a desired speed reduction of one or more rotating components of the turbine; and extracting an amount of power from the turbine using the electric motor based on the determined desired speed reduction.

[0087] A method as described in one or more of these clauses, wherein extracting an amount of power from the turbine using the electric machine based on the determined desired speed reduction comprises extracting an amount of power that is less than a maximum power extraction capacity of the electric machine.

[0088] A method as described in one or more of these clauses, wherein extracting an amount of power from the turbine using the electric machine based on the determined desired speed reduction comprises extracting an amount of power that is less than 80% of a maximum power extraction capacity of the electric machine.

[0089] A method according to one or more of these clauses, wherein the turbomachine comprises a high pressure turbine and a low pressure turbine, wherein the electric machine and the propeller are each coupled to the low pressure turbine, and wherein the one or more rotating components comprises the low pressure turbine.

[0090] A method according to one or more of these clauses, wherein determining the desired speed reduction of one or more rotating components of the turbine comprises determining a margin between a rotational speed parameter of the one or more rotating components and an upper limit for the rotational speed parameter of the one or more rotating components.

[0091] A method according to one or more of these clauses, wherein the electric machine is a first electric machine, wherein the turbine includes a high-pressure turbine and a low-pressure turbine, wherein the first electric machine and the propeller are each coupled to the low-pressure turbine, and wherein the hybrid-electric propulsion system further includes a second electric machine coupled to the high-pressure turbine.

[0092] A method according to one or more of these clauses, wherein extracting power from a turbine using an electric machine to slow one or more rotating components of the turbine in response to receiving data indicating a failure condition comprises: extracting power from a low-pressure turbine using a first electric machine; and extracting power from a high-pressure turbine using a second electric machine.

[0093] A method according to one or more of these clauses, wherein the failure condition is shaft shear failure.

[0094] A method as described in one or more of these clauses, wherein the failure condition is a fuel flow valve failure.

[0095] A method according to one or more of these clauses, wherein the failure condition is a variable geometry component failure.

[0096] A method according to one or more of these clauses, wherein the data indicative of a failure situation are data indicating that a rotational speed of the low-pressure turbine exceeds an upper rotational speed limit.

[0097] A method according to one or more of these clauses, wherein the turbomachine comprises a high pressure turbine and a low pressure turbine, wherein the electric machine and the propeller are each coupled to the low pressure turbine.

[0098] A method according to one or more of these clauses, wherein extracting power from the turbine using the electric machine to slow down one or more rotating components of the turbine comprises reducing the rotational speed of the low pressure turbine.

[0099] The method of one or more of these clauses, wherein extracting power from the turbine using the electric machine comprises extracting power from the turbine using the electric machine substantially simultaneously with reducing fuel flow to a combustion section of the turbine.

[0100] A method according to one or more of these clauses, wherein the electric machine is located inside a core air flow path of the turbine in a radial direction of the turbine.

[0101] A method according to one or more of these clauses, wherein the electric machine is located outside a core air flow path of the turbine in a radial direction of the turbine.

[0102] The method of one or more of these clauses, wherein extracting power from the turbine using the electric machine comprises extracting at least about twenty kilowatts of electrical power using the electric machine.

[0103] A method according to one or more of these clauses, wherein the hybrid electric propulsion system further comprises an electrical energy absorber, and wherein extracting power from the turbine using the electric machine comprises providing electrical power from the electric machine to the electrical energy absorber.

[0104] A method according to one or more of these clauses, wherein the electrical energy absorber is configured to store at least about twenty kilowatt-hours of electrical power.

[0105] A method according to one or more of these clauses, wherein the electrical energy absorber comprises an energy storage unit, a resistor bank or both.

[0106] The method according to one or more of these clauses, wherein reducing the fuel flow to the combustion section of the turbomachine comprises terminating the fuel flow to the combustion section of the turbomachine.

[0107] A method according to one or more of these clauses, wherein extracting power from a turbine using an electric machine to slow one or more rotating components of the turbine in response to receiving data indicating a failure condition includes extracting power from a low-pressure turbine using a first electric machine, and the method further includes: providing power to a high-pressure turbine using a second electric machine.

[0108] A method as described in one or more of these clauses, wherein receiving data indicative of a failure condition comprises receiving data indicative of a low voltage system failure condition.

[0109] A method as described in one or more of these clauses, wherein the failure condition is at least one of a shaft shear failure, a fuel flow valve failure, a variable geometry component failure, or a load loss condition.

[0110] The method according to one or more of these clauses, further comprising, in response to receiving data indicative of a failure condition, reducing fuel flow to a combustion section of the turbine.

[0111] The method according to one or more of these clauses, wherein reducing the fuel flow to the combustion section of the turbomachine comprises terminating the fuel flow to the combustion section of the turbomachine.

[0112] The method of one or more of these clauses, wherein extracting power from the turbine using the electric machine comprises extracting power from the turbine using the electric machine substantially simultaneously with reducing fuel flow to a combustion section of the turbine.

[0113] A hybrid electric propulsion system for an aircraft comprises: a turbine including a combustion section; a propeller coupled to the turbine; an electric motor also coupled to the turbine; and a controller configured to receive data indicating a failure condition of the hybrid electric propulsion system during operation of the turbine and, in response, extract power from the turbine using the electric motor.

[0114] A hybrid electric propulsion system according to one or more of these clauses, wherein, during the process of extracting power from the turbine using the electric motor, the controller is further configured to: determine a desired speed reduction of one or more rotating components of the turbine; and extract a certain amount of power from the turbine using the electric motor based on the determined desired speed reduction.

[0115] A hybrid electric propulsion system according to one or more of these clauses, wherein the turbine comprises a high pressure turbine and a low pressure turbine, wherein the electric machine and the propeller are each coupled to the low pressure turbine.

Claims

1. A method for operating a hybrid electric propulsion system for an aircraft, the hybrid electric propulsion system comprising a turbine, an electric machine coupled to the turbine, and a propeller coupled to the turbine, the method comprising: operating the turbine to drive the propeller; receiving data indicative of a failure condition of the hybrid electric propulsion system; extracting power from the turbine using the electric machine to slow one or more rotating components of the turbine in response to receiving data indicative of the failure condition; as well as wherein the turbomachine comprises a high-pressure turbine and a low-pressure turbine, wherein the motor and the propeller are each coupled to the low-pressure turbine; wherein extracting power from the turbine comprises extracting power from the low-pressure turbine using the electric machine, and wherein the method further comprises: Power is added to the high pressure turbine to increase the speed of the high pressure turbine.

2. The method according to claim 1, characterized in that Extracting power from the turbine using the electric machine to slow one or more rotating components of the turbine includes: determining a desired speed reduction of the one or more rotating components of the turbomachine; and The electric machine is used to extract an amount of power from the turbine based on the determined desired speed reduction.

3. The method according to claim 2, characterized in that Extracting the amount of power from the turbine using the electric machine based on the determined desired speed reduction includes extracting an amount of power that is less than a maximum power extraction capacity of the electric machine.

4. The method according to claim 2, characterized in that: Extracting the amount of power from the turbine using the electric machine based on the determined desired speed reduction includes extracting an amount of power that is less than 80% of a maximum power extraction capacity of the electric machine.

5. The method according to claim 2, characterized in that: Determining the desired speed reduction of the one or more rotating components of the turbomachine includes determining a margin between a rotational speed parameter of the one or more rotating components and an upper limit for the rotational speed parameter of the one or more rotating components.

6. The method according to claim 1, characterized in that The motor is a first motor wherein, The first electric machine and the propeller are each coupled to the low-pressure turbine, and wherein the hybrid-electric propulsion system further comprises a second electric machine coupled to the high-pressure turbine.

7. The method according to claim 6, characterized in that In response to receiving data indicative of the failure condition, extracting power from the turbine using the electric machine to slow one or more rotating components of the turbine comprises: extracting power from the low pressure turbine using the first electric machine; and The second electric machine is used to extract power from the high-pressure turbine.

8. The method according to claim 6, characterized in that In response to receiving data indicative of the failure condition, extracting power from the turbine using the electric machine to slow one or more rotating components of the turbine includes extracting power from the low-pressure turbine using the first electric machine, and the method further includes: The second electric machine is used to provide power to the high pressure turbine.

9. The method according to claim 8, characterized in that Receiving data indicative of a failure condition includes receiving data indicative of a low voltage system failure condition.

10. The method according to claim 1, characterized in that The failure condition is at least one of a shaft shear failure, a fuel flow valve failure, a variable geometry component failure, or a load loss condition.

11. The method according to claim 1, characterized in that: The turbomachine includes a high-pressure turbine and a low-pressure turbine, wherein the electric machine and the propeller are each coupled to the low-pressure turbine.

12. The method according to claim 1, characterized in that Extracting power from the turbine using the electric machine includes extracting at least twenty kilowatts of electrical power with the electric machine.

13. The method according to claim 1, characterized in that The hybrid electric propulsion system further includes an electrical energy absorber, and wherein extracting power from the turbine using the electric machine includes providing electrical power from the electric machine to the electrical energy absorber.

14. The method according to claim 13, characterized in that The electrical energy absorber includes an energy storage unit, a resistor group, or both.

15. The method according to claim 1, characterized in that Further including: In response to receiving the data indicative of the failure condition, fuel flow to a combustion section of the turbomachine is reduced.

16. The method according to claim 15, characterized in that Reducing fuel flow to the combustion section of the turbomachine includes terminating fuel flow to the combustion section of the turbomachine.

17. The method according to claim 16, characterized in that Extracting power from the turbine using the electric machine includes extracting power from the turbine using the electric machine substantially simultaneously with reducing fuel flow to the combustion section of the turbine.

18. A hybrid electric propulsion system for an aircraft, comprising: a turbomachine including a combustion section, a high pressure turbine, and a low pressure turbine; a propeller coupled to the low pressure turbine; an electric machine coupled to the low-pressure turbine; as well as A controller is configured to receive data indicative of a failure condition of the hybrid electric propulsion system during operation of the turbine and in response extract power from the low pressure turbine using the electric machine and add power to the high pressure turbine to increase the speed of the high pressure turbine.

19. The hybrid electric propulsion system according to claim 18, characterized in that: During the process of extracting power from the turbine using the electric machine, the controller is further configured to: determine a desired speed reduction of the one or more rotating components of the turbine, and extract an amount of power from the turbine using the electric machine based on the determined desired speed reduction.

Images