Systems and methods for power transfer in cryogenic fuel applications

A fuel power transfer system for an engine may include a cryogenic fuel supply, a fuel pump in fluid communication with the cryogenic fuel supply, a multi-position valve in fluid communication with the fuel pump and a combustion chamber of the engine, a fuel turbine operatively coupled to the fuel pump and having a primary discharge port in fluid communication with the combustion chamber, a primary heat exchanger in fluid communication between the multi-position valve and the fuel turbine, and a gearbox operatively coupled to the fuel turbine and the fuel pump and configured to transfer power from the fuel turbine to the engine.

FIELD

The present disclosure relates generally to aircraft systems and, more particularly, to aircraft power plant and auxiliary systems.

BACKGROUND

It has been proposed to operate gas turbine engines, such as those used to propel aircraft, by using more than one type of fuel. Such fuels may be used together simultaneously or selectively during differing periods of operation. In such regimes, it is usual to use a conventional fuel such as, for example, kerosene as the primary fuel and a secondary fuel such as a cryogenic liquid fuel. The secondary fuel may be burned to power the engine either simultaneously with the primary fuel or as a substitute during certain periods of engine operation. Operating engines with blended traditional and cryogenic fuels may tend to enhance engine performance.

SUMMARY

In various embodiments, a fuel power transfer system for an engine comprises a cryogenic fuel supply, a fuel pump in fluid communication with the cryogenic fuel supply, a multi-position valve in fluid communication with the fuel pump and a combustion chamber of the engine, a fuel turbine operatively coupled to the fuel pump and having a primary discharge port in fluid communication with the combustion chamber, a primary heat exchanger in fluid communication between the multi-position valve and the fuel turbine, and a gearbox operatively coupled to the fuel turbine and the fuel pump and configured to transfer power from the fuel turbine to the engine.

In various embodiments, a motor-generator may be operatively coupled to the gearbox and selectively configurable to operate as a motor or a generator. In various embodiments, an auxiliary heat exchanger may be in fluid communication between the multi-position valve and the combustion chamber. In various embodiments, the fuel pump and the fuel turbine are operatively coupled via a common shaft. In various embodiments, the motor-generator is coupled to the gearbox via an accessory clutch and wherein the gearbox is configured to transfer power from the fuel turbine to the engine via a power transfer clutch. In various embodiments, the system further comprises a controller, a sensor in communication with the controller and configured to provide sensor feedback and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising, determining a startup condition, controlling the motor-generator in response to the startup condition, controlling the multi-position valve in response to the startup condition, and controlling the accessory clutch in response to the startup condition.

In various embodiments, the operations further comprise determining an auxiliary heat condition and controlling the multi-position valve to direct a portion of the fuel to an auxiliary heat exchanger in fluid communication with the combustion chamber in response to the auxiliary heat condition. In various embodiments, the operations further comprise determining an operating power condition, controlling the multi-position valve in response to the operating power condition, and controlling at least one of the accessory clutch or the power transfer clutch in response to the operating power condition.

In various embodiments, the system comprises a primary turbine discharge valve configured to be controlled by the controller and in fluid communication between the combustion chamber and the primary discharge port, and a secondary turbine discharge valve configured to be controlled by the controller and in fluid communication between the combustion chamber and a secondary discharge port of the fuel turbine, wherein each of the primary turbine discharge valve and the secondary turbine discharge valve are configured to interrupt fluid communication with the combustion chamber. In various embodiments, the operations further comprise determining an intermediate operating power condition, controlling at least one of the accessory clutch or the power transfer clutch in response to the intermediate operating power condition, and controlling at least one of the primary turbine discharge valve or the secondary turbine discharge valve in response to the intermediate operating power condition.

In various embodiments, the operations further comprise selecting a motor mode of the motor generator in response to the startup condition, selecting a generator mode of the motor generator in response to the operating power condition, and controlling an electrical load disconnect relay in response to the operating power condition. In various embodiments, the sensor includes a first fuel pressure sensor in fluid communication with the primary discharge port and a second fuel pressure sensor in fluid communication with the secondary discharge port, wherein the operations further comprise receiving a primary discharge port pressure and a secondary discharge port pressure, and determining the operating power condition or the intermediate operating power condition based on the primary discharge port pressure and the secondary discharge port pressure.

In various embodiments, a method of controlling a fuel power transfer system for an engine comprises determining a startup condition, controlling a motor-generator in response to the startup condition, controlling a multi-position valve in response to the startup condition, and controlling an accessory clutch in response to the startup condition.

In various embodiments, the method includes determining an auxiliary heat condition and controlling the multi-position valve to direct a portion of a fuel to an auxiliary heat exchanger in fluid communication with a combustion chamber of the engine in response to the auxiliary heat condition. In various embodiments, the method includes determining an operating power condition, controlling the multi-position valve in response to the operating power condition, and controlling at least one of the accessory clutch or the power transfer clutch in response to the operating power condition. In various embodiments, the method includes determining an intermediate operating power condition, controlling at least one of the accessory clutch or the power transfer clutch in response to the intermediate operating power condition, and controlling at least one of the primary turbine discharge valve or the secondary turbine discharge valve in response to the intermediate operating power condition.

In various embodiments, an article of manufacture is provided. The article of manufacture may include a tangible, non-transitory computer-readable storage medium having instructions stored thereon that, in response to execution by a processor, cause the processor to perform operations comprising determining a startup condition, controlling a motor-generator in response to the startup condition, controlling a multi-position valve in response to the startup condition, and controlling an accessory clutch in response to the startup condition.

In various embodiments, the operations include determining an operating power condition, controlling the multi-position valve in response to the operating power condition, and controlling at least one of the accessory clutch or the power transfer clutch in response to the operating power condition. In various embodiments, the operations include determining an intermediate operating power condition, controlling at least one of the accessory clutch or the power transfer clutch in response to the intermediate operating power condition, and controlling at least one of the primary turbine discharge valve or the secondary turbine discharge valve in response to the intermediate operating power condition. In various embodiments, the operation further comprise operations further comprise selecting a motor mode of the motor generator in response to the startup condition, selecting a generator mode of the motor generator in response to the operating power condition, and controlling an electrical load disconnect relay in response to the operating power condition.

DETAILED DESCRIPTION

All ranges and ratio limits disclosed herein may be combined. It is to be understood that unless specifically stated otherwise, references to “a,” “an,” and/or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the exemplary embodiments of the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not limitation.

The scope of the disclosure is defined by the appended claims and their legal equivalents rather than by merely the examples described. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, coupled, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

With reference toFIG. 1A, an aircraft10is illustrated in accordance with various embodiments. Aircraft10comprises a fuselage12, wings14, cockpit controls16, landing gear18, and a propulsion system, such as gas turbine engines20. In various embodiments, aircraft10may include a fuel and power transfer system200.

In various embodiments and with reference toFIG. 1B, a gas turbine engine20is provided. Gas turbine engine20may be a two-spool turbofan that generally incorporates a fan section22, a compressor section24, a combustor section26and a turbine section28. In operation, fan section22can drive air along a bypass flow-path B while compressor section24can drive air through a core flow-path C for compression and communication into combustor section26then expansion through turbine section28. In various embodiments, gas turbine engine20may incorporate a plurality of engine accessories such as, for example, components of power transfer system200. Although depicted as a turbofan gas turbine engine20herein, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of engines including turbojet engines, a low-bypass turbofans, a high bypass turbofans, reciprocating engines, or any other internal combustion engine known to those skilled in the art.

Gas turbine engine20may generally comprise a low speed spool30and a high speed spool32mounted for rotation about an engine central longitudinal axis A-A′ relative to an engine static structure36via one or more bearing systems38(shown as bearing system38-1and bearing system38-2). It should be understood that various bearing systems38at various locations may alternatively or additionally be provided, including for example, bearing system38, bearing system38-1, and bearing system38-2.

Low speed spool30may generally comprise an inner shaft40that interconnects a fan42, a low pressure (or first) compressor section44(also referred to a low pressure compressor) and a low pressure (or first) turbine section46. Inner shaft40may be connected to fan42through a geared architecture48that can drive fan42at a lower speed than low speed spool30. Geared architecture48may comprise a gear assembly60enclosed within a gear housing62. Gear assembly60couples inner shaft40to a rotating fan structure. High speed spool32may comprise an outer shaft50that interconnects a high pressure compressor (“HPC”)52(e.g., a second compressor section) and high pressure (or second) turbine section54. A combustor56may be located between HPC52and high pressure turbine54. A mid-turbine frame57of engine static structure36may be located generally between high pressure turbine54and low pressure turbine46. Mid-turbine frame57may support one or more bearing systems38in turbine section28. Inner shaft40and outer shaft50may be concentric and rotate via bearing systems38about the engine central longitudinal axis A-A′, which is collinear with their longitudinal axes. As used herein, a “high pressure” compressor or turbine experiences a higher pressure than a corresponding “low pressure” compressor or turbine.

The core airflow C may be compressed by low pressure compressor44then HPC52, mixed and burned with fuel in combustor56, then expanded over high pressure turbine54and low pressure turbine46. Mid-turbine frame57includes airfoils59which are in the core airflow path. Low pressure turbine46, and high pressure turbine54rotationally drive the respective low speed spool30and high speed spool32in response to the expansion.

Gas turbine engine20may be, for example, a high-bypass geared aircraft engine. In various embodiments, the bypass ratio of gas turbine engine20may be greater than about six (6). In various embodiments, the bypass ratio of gas turbine engine20may be greater than ten (10). In various embodiments, geared architecture48may be an epicyclic gear train, such as a star gear system (sun gear in meshing engagement with a plurality of star gears supported by a carrier and in meshing engagement with a ring gear) or other gear system. Geared architecture48may have a gear reduction ratio of greater than about 2.3 and low pressure turbine46may have a pressure ratio that is greater than about 5. In various embodiments, the bypass ratio of gas turbine engine20is greater than about ten (10:1). In various embodiments, the diameter of fan42may be significantly larger than that of the low pressure compressor44, and the low pressure turbine46may have a pressure ratio that is greater than about (5:1). Low pressure turbine46pressure ratio may be measured prior to inlet of low pressure turbine46as related to the pressure at the outlet of low pressure turbine46prior to an exhaust nozzle. It should be understood, however, that the above parameters are exemplary of various embodiments of a suitable geared architecture engine and that the present disclosure contemplates other gas turbine engines including direct drive turbofans.

In various embodiments, the next generation of turbofan engines may be designed for higher efficiency which is associated with higher pressure ratios and higher temperatures in the HPC52. These higher operating temperatures and pressure ratios may create operating environments that may cause thermal loads that are higher than the thermal loads encountered in conventional turbofan engines, which may shorten the operational life of current components.

In various embodiments, HPC52may comprise alternating rows of rotating rotors and stationary stators. Stators may have a cantilevered configuration or a shrouded configuration. More specifically, a stator may comprise a stator vane, a casing support and a hub support. In this regard, a stator vane may be supported along an outer diameter by a casing support and along an inner diameter by a hub support. In contrast, a cantilevered stator may comprise a stator vane that is only retained and/or supported at the casing (e.g., along an outer diameter).

In various embodiments, rotors may be configured to compress and spin a fluid flow. Stators may be configured to receive and straighten the fluid flow. In operation, the fluid flow discharged from the trailing edge of stators may be straightened (e.g., the flow may be directed in a substantially parallel path to the centerline of the engine and/or HPC) to increase and/or improve the efficiency of the engine and, more specifically, to achieve maximum and/or near maximum compression and efficiency when the straightened air is compressed and spun by rotor64.

With additional reference toFIG. 2, system200is shown integrated with the gas turbine engine20of aircraft10according to various embodiments. System200includes a controller202which may be integrated into computer systems onboard aircraft10. In various embodiments, controller202may be configured as a central network element or hub to access various systems, engines, and components of system200. Controller202may comprise a network, computer-based system, and/or software components configured to provide an access point to various systems, engines, and components of system200. In various embodiments, controller202may comprise a processor. In various embodiments, controller202may be implemented in a single processor. In various embodiments, controller202may be implemented as and may include one or more processors and/or one or more tangible, non-transitory memories and be capable of implementing logic. Each processor can be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. Controller202may comprise a processor configured to implement various logical operations in response to execution of instructions, for example, instructions stored on a non-transitory, tangible, computer-readable medium configured to communicate with controller202. In this regard, controller202may be configured to control various components of system200via control signals208.

System program instructions and/or controller instructions may be loaded onto a non-transitory, tangible computer-readable medium having instructions stored thereon that, in response to execution by a controller, cause the controller to perform various operations. The term “non-transitory” is to be understood to remove only propagating transitory signals per se and includes all standard computer-readable media that are not only propagating transitory signals per se.

In various embodiments, controller202may be in electronic communication with a pilot through a control interface204of cockpit controls16, for example, a multifunction display, a switch panel, and/or the like which an operator can operate. The control interface204may enable the operator to interact with system200for example, to issue commands, display information such as, for example, warnings, or receive outputs. Control interface204may comprise any suitable combination of hardware, software, and/or database components.

System200comprises one or more feedback elements to monitor and measure aircraft10and gas turbine engine20characteristics. For example, controller202is in electronic communication with sensors206that may be coupled to or in direct electronic communication with aircraft systems such as, for example, propulsion systems, fuel systems (e.g., primary and secondary fuel systems), and/or the like. Controller202may be in electronic communication with the full suite of aircraft sensors and other data sources available within and without the aircraft10. Sensors206may comprise a temperature sensor, a torque sensor, a speed sensor, a pressure sensor, a position sensor, an accelerometer, a voltmeter, an ammeter, a wattmeter, an optical sensor, or any other suitable measuring device known to those skilled in the art. Sensors206may be configured to transmit measurements to controller202, thereby providing sensor feedback about the measured system. The sensor feedback may be, for example, a speed signal, or may be position feedback, temperature feedback, pressure feedback or other data.

System200includes a cryogenic fuel supply210which may be configured to store a fuel such as a cryogenic liquid fuel. In various embodiments, the fuel may be one of molecular hydrogen, methane, ethane, propane, butane, natural gas and/or the like. The cryogenic fuel supply210is in fluid communication with a fuel pump212via supply line214. The fuel pump212is configured to increase the pressure of the fuel (such as, for example, above a critical pressure of the fuel) and supply the fuel at an increased pressure to a multi-position valve216. In various embodiments, the fuel pump212is coupled to a gearbox218and receives operative power therefrom such as, for example, via a pump shaft.

In various embodiments, gearbox218may receive operative power from the gas turbine engine20. For example, in various embodiments, gearbox218may be coupled to any of the spools (e.g.,30,32) and/or shafts (e.g.,40,50) of gas turbine engine20by a power transfer shaft220. The power transfer shaft220may be coupled to the gearbox218through a power transfer clutch222. In this regard, the gearbox218may be selectively mechanically coupled to the gas turbine engine20and thereby configured to transmit to or receive power from the gas turbine engine20.

In various embodiments and in like regard, gearbox218may be mechanically coupled to a motor-generator224via accessory shaft226and accessory clutch228. Motor-generator224may be selectively operable as a motor or as a generator. In this regard, in motor operation, motor-generator224may be configured to provide operative power to the fuel pump212via the gearbox218by engaging the accessory clutch228. Similarly, motor-generator224may be configured to provide operative power to the gas turbine engine20via the gearbox218by engaging the accessory clutch228and the power transfer clutch222. Motor-generator224may be coupled to an electrical load230such as, for example, an electrical power system of aircraft10. When configured to operate as a generator, motor-generator224may supply electrical power to the electrical load230in response to receiving operative power from the gearbox218. In various embodiments, the electrical load230may be disconnected from the motor-generator224by, for example, an electrical load disconnect relay232.

In various embodiments, a fuel turbine234may be operatively coupled to the fuel pump212and/or the gearbox218such as, for example, via a common shaft237. In various embodiments, the fuel turbine234may provide input to the gearbox218and subsequently drive the fuel pump212and motor-generator224via geared shafting configured to provide desired rotational speeds for each component. The fuel turbine234may be a variable pressure discharge turbine and may include a primary discharge port236(i.e., a first discharge port) and a secondary discharge port238(i.e., a second discharge port) in fluid communication with a combustion chamber of the gas turbine engine20(e.g., combustor56). In various embodiments, each discharge port of the fuel turbine234may be in fluid communication with a respective control valve configured to regulate and/or interrupt fluid communication with the combustion chamber. For example, a primary turbine discharge valve240and a secondary turbine discharge valve242(i.e., a first valve and a second valve) may be coupled to the respective discharge port of the fuel turbine234. In various embodiments, sensors206may include a first fuel pressure sensor244may be in fluid communication with the primary discharge port236and a second fuel pressure sensor246may be in fluid communication with the secondary discharge port238.

In various embodiments, multi-position valve216may be in fluid communication with a primary heat exchanger248. The multi-position valve216may be configured to send a portion of the fuel from fuel pump212through the primary heat exchanger248. The primary heat exchanger248may extract heat from the gas turbine engine20and impart heat energy to the fuel. In this regard, the primary heat exchanger248may be configured to vaporize and expand the fuel and deliver heated gaseous fuel to the inlet250of the fuel turbine234. It will be appreciated that fuel serves as a working fluid for the fuel turbine234which may thereby extract energy from the working fluid to drive loads such as the fuel pump212, gearbox218, motor-generator224, and power transfer shaft220and that these loads may be modulated (e.g., by commands from controller202) via clutches222and228. The heated gaseous fuel may be further expanded by the fuel turbine234and may be directed to the combustion chamber via the primary discharge port236and/or the secondary discharge port238.

In various embodiments, multi-position valve216may be in fluid communication with an auxiliary heat exchanger252in fluid communication with the combustion chamber. The multi-position valve216may be selectively configurable to direct a portion or an entirety of the fuel pump212fuel output directly to any of the combustion chamber, the auxiliary heat exchanger252, or the primary heat exchanger248. In various embodiments, the auxiliary heat exchanger252may be in fluid communication with the primary turbine discharge valve240and/or the secondary turbine discharge valve242. In this regard, by selecting a position of the multi-position valve in response to a startup condition, the auxiliary heat exchanger252may be configured to preheat fuel from the fuel pump212to a gaseous state during the startup condition prior to introduction to the combustion chamber. In like regard, by selecting a position of the multi-position valve in response to an operating power condition, the auxiliary heat exchanger252may be configured to reheat the expanded gaseous fuel from either of the primary discharge port236and/or the secondary discharge port238prior to introduction to the combustion chamber during the operating power condition.

With additional reference toFIG. 3, a method300of controlling a fuel and power transfer system is illustrated according to various embodiments. Method300comprises determining a startup condition, controlling a motor-generator in response to the startup condition, controlling a multi-position valve in response to the startup condition, and controlling an accessory clutch in response to the startup condition (step302). For example, controller202may determine a startup condition in response to an input from control interface204such as an engine start command. The controller202may command the accessory clutch228to engage and may select a motor mode of the motor-generator224. In this regard, controller202may provide operative force to the fuel pump212via gearbox218. Stated another way, the controller202may control and/or configure the multi-position valve216to enable fluid communication between the fuel pump212and the combustion chamber but bypass the primary heat exchanger248in response to the startup condition.

In various embodiments, method300includes controller202determining an auxiliary heat condition and controlling the multi-position valve216to direct a portion of a fuel to the auxiliary heat exchanger252(step304). Method300includes determining an operating power condition, controlling the multi-position valve in response to the operating power condition, and controlling at least one of the accessory clutch or the power transfer clutch in response to the operating power condition (step306). In various embodiments, method300includes determining an intermediate operating power condition, controlling at least one of the accessory clutch or the power transfer clutch in response to the intermediate operating power condition, and controlling at least one of the primary turbine discharge valve or the secondary turbine discharge valve in response to the intermediate operating power condition (step308). In various embodiments, the controller202may determine the intermediate operating condition based on a power setting of the turbine engine20such as, for example, a cruise power setting which may be entered via the control interface204. The intermediate operating condition may be determined based on sensors206measurements such as, for example, measurements at a P3 (e.g., a combustor inlet pressure) station of the turbine engine20or a fuel pressure measurement. In like regard, an operating power condition may be determined where the measurements are relatively greater than that of the intermediate operating condition such as, for example, a full power setting which may be entered via the control interface204. In various embodiments, method300includes comprise selecting a motor mode of the motor generator in response to the startup condition, selecting a generator mode of the motor generator in response to the operating power condition, and controlling an electrical load disconnect relay in response to the operating power condition (step310).

For example, controller202may determine an operating power condition or an intermediate operating power condition of gas turbine engine20such as, for example, based on sensor data from sensors206or in response to a power setting command from control interface204. The controller202may receive a primary discharge port pressure from the first fuel pressure sensor244may a secondary discharge port pressure from the second fuel pressure sensor246. In this regard, the controller202may determine the operating power condition or the intermediate operating power condition based on the primary discharge port pressure and the secondary discharge port pressure.

Controller202may control the multi-position valve216to enable fluid communication between the fuel pump212, the primary heat exchanger248, and the inlet250of the fuel turbine234. The controller202may command accessory clutch228to engage and may command the power transfer clutch222to engage. The controller202may select a generator mode of the motor-generator224and may command the electrical load disconnect relay232to close and thereby enable electronic communication between the electrical load230and the motor-generator224. In this regard, the controller202may configure the fuel turbine234to transmit power to the gearbox218and thereby transfer power between the gas turbine engine20and the electrical load230.

In various embodiments controller202may determine an intermediate operating power condition in response to an intermediate power setting from the control interface204or in response to sensor206data such as gas turbine engine20station temperatures, rotor speeds, internal pressures, inlet250temperature, the fuel turbine discharge port pressures and/or the like. The controller202may control or module each of the primary turbine discharge valve240and a secondary turbine discharge valve242in response to the intermediate power condition. The controller202may command the power transfer clutch to disengage. In this regard, controller202may control the fuel turbine234discharge pressure to remain above the combustion chamber operating pressure and thereby tend to inhibit back driving of the fuel turbine234by the gas turbine engine20.