Systems and methods for providing output products to a combustion chamber of a gas turbine engine

Abstract

A system and method including a fuel cell stack extending around a combustion chamber, the fuel cell stack configured to provide an output product to the combustion chamber to achieve at least one of a late lean injection and a desired combustor gas concentration profile. The fuel cell stack is positioned at a downstream section of the combustion chamber in an axial direction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to systems and methods for providing output products to a combustion chamber of a gas turbine engine, the propulsion system including a fuel cell. BACKGROUND

[0002] A gas turbine engine generally includes a turbine machine and a rotor assembly. Gas turbine engines, such as turbofan engines, can be used for aircraft propulsion. In the case of a turbofan engine, the turbine machine includes, in serial flow order, a compressor section, a combustion section, and a turbine section, and the rotor assembly is configured as a fan assembly.

[0003] During operation, air is compressed in the compressor section and mixed with fuel and ignited in the combustion section to generate combustion gases that flow downstream through the turbine section. The turbine section extracts energy from the combustion gases for rotating the compressor section and the fan assembly, powering the gas turbine engine and propelling an aircraft containing such a gas turbine engine in flight.

[0004] The combustor power is adjusted to meet the fan speed demand or thrust demand. The temperature of the combustor of the combustion section can depend on the combustor power and can be an operating limit of the gas turbine engine. Thus, achieving combustor power can cause the combustor temperature to change in a manner that increases emissions. If the combustor temperature is too low, carbon monoxide (CO) can increase. And if the combustor temperature is too high, nitrogen oxides (NOx) can increase. Accordingly, a system and method that is capable of achieving a desired combustor power while reducing emissions would be welcomed in the art. x BRIEF DESCRIPTION OF DRAWINGS

[0005] A complete and enabling disclosure of the present disclosure, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification, which is to be taken in conjunction with the appended drawings, wherein:

[0006] Figure 1 is a cross-sectional view of a gas turbine engine according to exemplary aspects of the present disclosure.

[0007] Figure 2 is a perspective view of an integrated fuel cell and combustor assembly according to the present disclosure.

[0008] Figure 3 is a partial cutaway cross-sectional perspective view of a fuel cell stack of the integrated fuel cell and combustor assembly of Figure 2

[0009] Figure 4 is a schematic view of a gas turbine engine including an integrated fuel cell and combustor assembly according to exemplary aspects of the present disclosure. ​​

[0010] Figure 5 is a schematic illustration of a vehicle and propulsion system according to example aspects of the present disclosure.

[0011] Figure 6 is a cross-sectional view of an integrated fuel cell and combustor assembly according to example aspects of the present disclosure.

[0012] Figure 7 is a cross-sectional view of an integrated fuel cell and combustor assembly according to example aspects of the present disclosure.

[0013] Figure 8 is a cross-sectional view of an integrated fuel cell and combustor assembly according to example aspects of the present disclosure.

[0014] Figure 9 is a cross-sectional view of an integrated fuel cell and combustor assembly according to example aspects of the present disclosure. DETAILED DESCRIPTION

[0015] Reference will now be made in detail to the presently preferred embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. The detailed description uses numerical and letter designations

[0016] 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. Furthermore, unless otherwise indicated, the description of embodiments herein should not be viewed as relating to a particular embodiment or implementation rather than another, and the description of features in each embodiment should not be interpreted as an indication that the feature is essential to or critical for that embodiment.

[0017] For purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", and derivatives thereof shall relate to the embodiments as they are oriented in the drawing figures. However, it is to be understood that the embodiments can assume various alternative orientations and, unless otherwise specified, the specific

[0018] As used herein, the terms "first", "second", and "third" can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0019] The terms "forward" and "aft" 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, with respect to a gas turbine engine, forward refers to a position closer to the engine inlet and aft refers to a position closer to the engine nozzle or exhaust.

[0020] The terms "upstream" and "downstream" refer to the relative direction with respect to the flow of fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid flows and "downstream" refers to the direction to which the fluid flows.

[0021] Unless specified otherwise herein, the terms "coupled," "fixed," "attached to," and the like, mean either directly coupled, fixed, or attached by one or more intermediate components or features.

[0022] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0023] The term "at least one of' in the context of, for example, "at least one of A, B, and C" or "at least one of A, B, or C" means only A, only B, only C, or any combination of A, B, and C.

[0024] Approximating language as used throughout the specification and claims is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is directed. Accordingly, a value modified by a term or terms, such as "about," "approximately," and "substantially," is not limited to the precise value specified. In at least some instances, the approximating language can correspond to the precision with which the instrument used to measure the value, or the method or machinery used to construct or manufacture the components and / or systems actually measures the values. For example, the approximating language can refer to a margin of error within 1%, 2%, 4%, 10%, 15%, or 20% of the value specified.

[0025] Approximating language as used throughout the specification and claims is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is directed. Accordingly, a value modified by a term or terms, such as "about," "approximately," and "substantially," is not limited to the precise value specified. In at least some instances, the approximating language can correspond to the precision with which the instrument used to measure the value, or the method or machinery used to construct or manufacture the components and / or systems actually measures the values. For example, the approximating language can refer to a margin of error within 1%, 2%, 4%, 10%, 15%, or 20% of the value specified.

[0026] Ratios, concentrations, amounts, and other numerical data can be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. As an example, a range of "1 to 10" should be interpreted to include not only the explicitly recited limits of 1 and 10, but also the individual numbers 2, 3, 4, 5, 6, 7, 8, and 9, as well as sub-ranges such as 1-6.3, 4.1-8.3, 10, and 1.1-1.4, etc. In this example, the range of numbers

[0027] "Third flow" as used herein refers to a non-primary gas flow that is capable of increasing fluid energy to produce a small amount of total propulsion system thrust. The pressure ratio of the third flow can be higher than the pressure ratio of a primary propulsion flow (e.g., a bypass or propeller driven propulsion flow).

[0028] Thrust can be generated either through a dedicated nozzle or by mixing the airflow passing through a third stream with the main propulsion stream or core airflow (e.g., mixing it into a common nozzle).

[0029] In some exemplary embodiments, the operating temperature of the airflow through the third stream can be lower than the maximum compressor temperature of the engine.

[0030] The emission temperature, and more specifically, can be below 350 degrees Fahrenheit (such as below 300 degrees Fahrenheit, such as below 250 degrees Fahrenheit, such as below 200 degrees Fahrenheit, and at least as high as the ambient temperature). In some exemplary embodiments, this

[0031] These operating temperatures can facilitate heat transfer to or from the airflow passing through the third flow and the separate fluid flow. Furthermore, in some exemplary embodiments, under takeoff conditions, or more specifically, under operating conditions of sea-level rated takeoff power, static flight speed, and an ambient temperature of 86 degrees Fahrenheit, the airflow through the third flow can contribute less than 50% (and at least, for example, 2%) of the total engine thrust.

[0032] 0 Furthermore, in some exemplary embodiments, the airflow aspect of the third flow (e.g., airflow, mixing, or exhaust)

[0033] The aforementioned exemplary percentage contribution to total thrust can be passively adjusted during engine operation or purposefully modified by using engine control features such as fuel flow, motor power, variable stator, variable inlet guide vanes, valves, variable exhaust geometry, or fluid characteristics to adjust or optimize overall system performance under a wide range of potential operating conditions.

[0034] 5. The term "turbine" or "turbomachinery" refers to one or more compressors, generators, or other components that together generate torque output.

[0035] A machine with a hot section (e.g., a combustion section) and one or more turbines.

[0036] The term "gas turbine engine" refers to an engine that has a turbine as its power source, in whole or in part. Examples of gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, and hybrid electric versions of one or more of these engines.

[0037] 0When used with compressor, turbine, shaft or spool components, etc., the terms "low" and "high", or their respective comparative forms (e.g., more "low" and more "high", where applicable), all refer to relative speeds within the engine, unless otherwise noted. For example, "low turbine" or "low speed turbine" defines a component configured to operate at a lower rotational speed (such as a maximum allowable rotational speed) than a "high turbine" or "high speed turbine" at the engine.

[0038] The term "equivalence ratio" refers to the ratio of the actual fuel / air ratio to the stoichiometric fuel / air ratio. Stoichiometric combustion occurs when all the oxygen is consumed in the reaction and there is no molecular oxygen (O2) in the products.

[0039] If the equivalence ratio is equal to one, the combustion is stoichiometric. If it is <1, the combustion is lean (lean fuel) with excess air, and if it is >1, the combustion is rich (rich fuel) with incomplete combustion. The equivalence ratio is the inverse of the air-fuel ratio.

[0040] Exhaust gas from an aircraft gas turbine engine consists of CO, carbon dioxide (CO2), water vapor (H2O), unburned hydrocarbons (UHC), particulate matter (primarily carbon), NO x and excess atmospheric oxygen and nitrogen.

[0041] As used herein, a "late lean injection system" can be generally described as a system for injecting a mixture of fuel and air into a working fluid stream at any point downstream of the primary fuel nozzles of the combustor and upstream of the turbine. In certain embodiments, a "late lean injection system" is more specifically described as a system for injecting a fuel / air mixture into the aft end of the primary combustion chamber defined by the liner. Generally speaking, one of the goals of a late lean injection system includes enabling fuel combustion to occur downstream of the primary combustor / primary combustion zone. This type of operation can be used to improve NO x performance.

[0042] If the combustor temperature is too low, carbon monoxide (CO) can increase. And if the combustor temperature is too high, nitrogen oxides (NO x ) can increase. If the residence time in the flame zone is too long, NO x may increase. And if the residence time in the flame zone is too short, CO can increase. The equivalence ratio at different locations in the combustor also affects the emissions output.

[0043] Systems and methods provide output products from a fuel cell to a combustion chamber of a gas turbine engine. In particular, the output products can be provided according to a desired profile of the output products. For example, the output products can be provided at a downstream location of the combustion chamber to reduce a residence time of the output products in the combustion chamber, thereby reducing emissions of the combustion chamber. Further, the systems and methods described herein can provide a desired temperature profile and / or profile of the output products along a length of the combustion chamber. For example, the profile of the output products can be determined such that a temperature along the length of the combustion chamber is within a low-emission temperature range. The output products can be provided at different locations along the length of the combustion chamber to move the temperature within the low-emission temperature range by increasing or decreasing the temperature, thereby reducing emissions.

[0044] Reference will now be made to the drawings wherein like numerals refer to like components throughout. Figure 1 A schematic cross-sectional view of an engine in accordance with example embodiments of the present disclosure is provided. The engine can be incorporated into a vehicle. For example, the engine can be an aeroengine incorporated into an aircraft. However, alternatively, the engine can be any other suitable type of engine for any other suitable vehicle.

[0045] For the depicted embodiment, the engine is configured as a high-bypass gas turbine engine 100. As Figure 1 shown, the gas turbine engine 100 defines an axial direction A (extending parallel to a centerline axis 101 provided for reference), a radial direction R, and a circumferential direction (extending about the axial direction A; not shown in the drawings). Generally, the gas turbine engine 100 includes a fan section 102 and a turbine 104 disposed downstream of the fan section 102. Figure 1

[0046] The depicted example turbine 104 generally includes a substantially tubular outer casing 106 defining an annular inlet 108. The outer casing 106 encloses, in serial flow relationship: a compressor section including a booster or low pressure (LP) compressor 110 and a high pressure (HP) compressor 112; a combustion section 114; a turbine section including a high pressure (HP) turbine 116 and a low pressure (LP) turbine 118; and an ejection exhaust nozzle section 120. The compressor section, the combustion section 114, and the turbine section together at least partially define a core air flowpath 121 extending from the annular inlet 108 to the ejection exhaust nozzle section 120. The turbine fan engine further includes one or more drive shafts. More specifically, the turbine fan engine includes a high pressure (HP) shaft or spool 122 drivingly connecting the HP turbine 116 to the HP compressor 112, and a low pressure (LP) shaft or spool 124 drivingly connecting the LP turbine 118 to the LP compressor 110.

[0047] ​For the depicted embodiment, the fan section 102 includes a fan 126 having a plurality of fan blades 128 coupled to a disk 130 in a spaced apart manner. The fan blades 128 and disk 130 are rotatable together about the centerline axis 101 by the LP shaft 124. The disk 130 is covered by a rotatable front hub 132 that is aerodynamically shaped to facilitate airflow through the plurality of fan blades 128. Further, an annular fan casing or outer nacelle 134 is disposed circumferentially around at least a portion of the fan 126 and / or turbine 104. The nacelle 134 is supported relative to the turbine 104 by a plurality of circumferentially spaced outlet guide vanes 136. A downstream section 138 of the nacelle 134 extends over an outer portion of the turbine 104 so as to define a bypass airflow passage 140 therebetween.

[0048] In this manner, it will be appreciated that the gas turbine engine 100 generally includes a first flow (e.g., the core airflow path 121) and a second flow (e.g., the bypass airflow passage 140) extending parallel to the first flow. In certain example embodiments, the gas turbine engine 100 can further define a third flow, for example, extending from the LP compressor 110 to the bypass airflow passage 140 or to the environment. With this configuration, the LP compressor 110 can generally include a first compressor stage configured as a ducted intermediate fan and a downstream compressor stage. An inlet of the third flow can be positioned between the first compressor stage and the downstream compressor stage.

[0049] Still referring to Figure 1 The gas turbine engine 100 additionally includes an accessory gearbox 142 and a fuel delivery system 146. For the illustrated embodiment, the accessory gearbox 142 is located within the shroud / housing 106 of the turbine 104. Further, it will be appreciated that, for Figure 1In the depicted example embodiment, the accessory gearbox 142 is mechanically coupled to and rotatable with one or more shafts or spools of the turbine 104. For example, in the depicted example embodiment, the accessory gearbox 142 is mechanically coupled to and rotatable with the HP shaft 122 by a suitable gear train 144. The accessory gearbox 142 can provide power to one or more suitable accessory systems of the gas turbine engine 100 during at least certain operations, and can further provide power back to the gas turbine engine 100 during other operations. For example, for the illustrated embodiment, the accessory gearbox 142 is coupled to a starter motor / generator 152. The starter motor / generator can be configured to extract power from the accessory gearbox 142 and the gas turbine engine 100 to generate electricity during certain operations, and can provide power back to the accessory gearbox 142 and the gas turbine engine 100 (e.g., to the HP shaft 122) to add mechanical work back to the gas turbine engine 10 (e.g., for starting the gas turbine engine 100) during other operations.

[0050] Further, the fuel delivery system 146 generally includes a fuel source 148 (such as a fuel tank) and one or more fuel delivery lines 150. The one or more fuel delivery lines 150 provide a fuel flow through the fuel delivery system 146 to the combustion section 114 of the turbine 104 of the gas turbine engine 100. As will be discussed in greater detail below, the combustion section 114 includes an integrated fuel cell and combustor assembly 200. For the described embodiment, the one or more fuel delivery lines 150 provide a fuel flow to the integrated fuel cell and combustor assembly 200.

[0051] It will be appreciated, however, that Figure 1 The example gas turbine engine 100 depicted in FIG. 1 is provided by way of example only. In other example embodiments, any other suitable gas turbine engine can be used with aspects of the present disclosure. For example, in other embodiments, the turbine fan engine can be any other suitable gas turbine engine, such as a turboshaft engine, a turboprop engine, a turbojet engine, etc. In this way, it will be further appreciated that in other embodiments, the gas turbine engine can have any other suitable configuration, such as any other suitable number or arrangement of shafts, compressors, turbines, fans, etc. Further, although the example gas turbine engine 100 depicted in FIG. 1 includes a single combustion section 114, in other embodiments, the gas turbine engine can include any other suitable number of combustion sections. Figure 1The exemplary gas turbine engine depicted is schematically illustrated as a direct drive fixed pitch turbofan engine, but in other embodiments, the gas turbine engine of the present disclosure can be a geared gas turbine engine (i.e., including a gearbox between the fan 126 and the shaft (such as the LP shaft 124) that drives the fan), can be a variable pitch gas turbine engine (i.e., including a fan 126 having a plurality of fan blades 128 that are capable of rotating about their respective pitch axes), and the like. Moreover, although the exemplary gas turbine engine 100 includes a ducted fan 126, in other exemplary aspects, the gas turbine engine 100 can include a non-ducted fan 126 (or open rotor fan) without the nacelle 134. Moreover, although not depicted herein, in other embodiments, the gas turbine engine can be any other suitable type of gas turbine engine, such as a marine gas turbine engine.

[0052] Referring now to Figure 2 , a portion of a combustion section 114 is schematically illustrated that includes an integrated fuel cell and combustor assembly 200 used in the gas turbine engine 100 (described above with respect to Figure 1 , which is described as a gas turbine engine 100) in accordance with embodiments of the present disclosure. Figure 1

[0053] It will be appreciated that the combustion section 114 includes a compressor diffuser nozzle 202 and extends generally in an axial direction A between an upstream end and a downstream end. The combustion section 114 is fluidly coupled to the compressor section at the upstream end via the compressor diffuser nozzle 202 and is fluidly coupled to the turbine section at the downstream end.

[0054] The integrated fuel cell and combustor assembly 200 generally includes a fuel cell assembly 204 (depicted only partially in Figure 2 ; see also Figures 3-4 ) and a combustor 206. The combustor 206 includes an inner liner 208, an outer liner 210, a dome assembly 212, a shroud assembly 214, a swirler assembly 216, and a fuel flow line 218. The combustion section 114 generally includes an outer shell 220 that laterally surrounds the combustor 206 along a radial direction R5, and an inner shell 222 that is laterally inward of the combustor 206 along a radial direction R.

[0055]

[0056] The inner shell 222 and the inner liner 208 define an inner passage 224 therebetween, while the outer shell 220 and the outer liner 210 define an outer passage 226 therebetween. The inner shell 222, the outer shell 220, and the dome assembly 212 together at least partially define a combustion chamber 228 of the combustor 206.

[0057] ​​The dome assembly 212 is positioned near the upstream end of the combustion section 114 (i.e., closer to the upstream end compared to the downstream end) and includes an opening 229 for receiving and retaining the cyclone assembly 216. The cyclone assembly 216 also includes an opening for receiving and retaining the cyclone assembly 216.

[0058] Keep the fuel flow line 218 open.

[0059] Fuel flow line 218 is further connected to fuel source 148 located radially R outside housing 220 (see...). Figure 1 It is configured to receive fuel from fuel source 148. In this way, fuel flow line 218 can be fluidly connected to the above reference. Figure 1 Describes one or more fuel delivery pipelines 150.

[0060] 5. The hydrocyclone assembly 216 may include a plurality of hydrocyclones (not shown), which are configured to compress fluid.

[0061] The compressed fluid is swirled before being injected into the combustion chamber 228 to generate combustion gases. In the illustrated embodiment, the shroud assembly 214 is configured to hold the inner liner 208, outer liner 210, swirler assembly 216, and dome assembly 212 together.

[0062] During operation, the compressor diffuser nozzle 202 is configured to guide compressed fluid 230 from the compressor section to the combustion chamber.

[0063] Burner 206, wherein compressed fluid 230 is configured to mix with fuel within cyclone assembly 216 and burn within combustion chamber 2280 to generate combustion gases. The combustion gases are supplied to turbine section to drive one or more turbines of turbine section (e.g., high-pressure turbine 116 and low-pressure turbine 118).

[0064] During operation of the gas turbine engine 100, which includes an integrated fuel cell and combustor assembly 200, the flame within the combustion chamber 228 is maintained by a continuous flow of fuel and air. This is to provide fuel, for example, during the start-up of the gas turbine engine 100.

[0065] The integrated fuel cell and burner assembly 200 further includes an igniter 231 for igniting the fuel and air mixture. The igniter 231 can provide a spark or initial flame to ignite the fuel and air mixture within the combustion chamber 228. In some exemplary embodiments...

[0066] In the integrated fuel cell and burner assembly 200, a dedicated fuel cell igniter 233 (depicted in dashed lines) may be additionally included. Figure 2In some embodiments, the dedicated fuel cell igniter 233 is positioned downstream of at least a portion of the fuel cell, particularly downstream of at least a portion of a fuel cell stack (as described below). In this manner, the dedicated fuel cell igniter 233 can more effectively combust the output products of the fuel cell.

[0067] 0As described above and Figure 2 As schematically depicted in FIG. 2, the integrated fuel cell and combustor assembly 200 further includes a fuel cell assembly 204. The fuel cell stacks 232, 234 (e.g., fuel and air conditioning devices) of the fuel cell assembly 204 can be cylindrical (e.g., not necessarily circular cross-section) and extend around the outer liner 210 of the combustor 228 (e.g., as shown for the fuel cell stack 232) or within the inner liner 208 of the combustor 228 (e.g., fuel cell stack 234). Figure 3

[0068] For example, the combustor 206 is an annular combustor and the fuel cell stack 232 of the fuel cell assembly 204 extends around (or is integrated with) the outer liner 210 or housing (e.g., outer shell 220) of the combustor 206 that defines the combustion chamber 228. This configuration is discussed further below and shown in greater detail with reference to FIG. 3. Figure 3

[0069] Additionally or alternatively, the fuel cell stack 234 of the fuel cell assembly 204 extends within (or is integrated with) the inner liner 208 or housing (e.g., inner shell 222) of the combustor 206 that defines the combustion chamber 228.

[0070] In Figure 2 In some embodiments, the fuel cell stacks 232, 234 can be part of the same fuel cell assembly 204 (e.g., share common structures and components that facilitate operation of the fuel cell assembly 204).

[0071] However, alternatively, in other example embodiments, the first fuel cell stack 232 can be part of a first fuel cell assembly and the second fuel cell stack 234 can be part of a second fuel cell assembly (e.g., each having separate components that facilitate operation).

[0072] Operation of the fuel cell assembly 204, and more particularly the fuel cell stacks 232, 234 of the fuel cell assembly 204, will be described in greater detail below.

[0073] For the described embodiments, the fuel cell assembly 204 is configured as a solid oxide fuel cell (“SOFC”) assembly, including SOFC fuel cell stacks (e.g., having a plurality of SOFCs arranged in a circumferential direction).

[0074] ​​It will be appreciated that SOFCs are generally electrochemical conversion devices that generate electricity directly through oxidation of a fuel. Generally, fuel cell assemblies, and in particular fuel cells, are characterized by the electrolyte material used. The SOFCs of the present disclosure can generally include a solid oxide or ceramic electrolyte. Such fuel cells generally exhibit high overall thermoelectric efficiency, long-term stability, fuel flexibility, and low emissions.

[0075] Further, in other example embodiments, the fuel cell assembly 204 can include any other suitable number and arrangement of fuel cell stacks 232, 234 to distribute output products at various locations along the axial and circumferential directions of the combustion chamber 228 having different parameters (e.g., temperature, pressure, composition, etc.).

[0076] The example fuel cell assembly 204 further includes power converters 236, 238. The fuel cell assembly 204 is in electrical communication with the power converters 236, 238 by a plurality of power supply cables (not labeled).

[0077] The power converters 236, 238 control the current drawn from the respective fuel cell stacks 232, 234 of the fuel cell assembly 204 and can convert the power from direct current (“DC”) power to DC power at another voltage level or alternating current (“AC”) power. Similarly, in embodiments including multiple fuel cell assemblies described in greater detail below, each fuel cell assembly can have an associated power converter that controls the current drawn from the fuel cell assembly and can convert the power from DC power to DC power at another voltage level or AC power. The first power converter 236, the second power converter 238, and any other power converters can be electrically coupled to an electrical bus, such as the electrical bus 326 described below.

[0078] The integrated fuel cell and combustor assembly 200 further includes a fuel cell controller 240 in operable communication with the first power converter 236 and the second power converter 238 to, for example, send and receive communications and signals therebetween. For example, the fuel cell controller 240 can send current or power setpoint signals to the first power converter 236 and the second power converter 238 and can receive voltage or current feedback signals, for example, from the first power converter 235 and the second power converter 238. The fuel cell controller 240 is described in greater detail below with reference to FIG. 3. Figure 4 The fuel cell controller 240 is described in greater detail.

[0079] In certain embodiments described in further detail below, the fuel cell assembly 204 includes a plurality of fuel cell stacks distributed along the axial direction A of the combustor 206. Fuel (e.g., from the fuel source 148 or by elements of the fuel cell and combustor assembly 200 described herein) can be varied to the plurality of fuel cell stacks to distribute output products or fuel along the axial direction A of the combustor 206.

[0080] For example, a “late lean” approach uses more fuel burned at a downstream end of the combustor 206. The “late lean” approach can be implemented to reduce the residence time of fuel in the combustor 206.

[0081] As will be discussed in greater detail below, a fuel cell is an electrochemical device that can convert chemical energy from a fuel, such as hydrogen, to electrical energy through an electrochemical reaction of the fuel with an oxidant, such as oxygen contained in the atmosphere. Fuel cell systems can be advantageously used as energy supply systems because, when compared to at least certain existing systems, fuel cell systems can be considered environmentally superior and efficient.

[0082] To improve system efficiency and fuel utilization and reduce external water usage, the fuel cell system can include an anode recirculation loop. Because a single fuel cell can only generate about 1 V of voltage, multiple fuel cells can be stacked together, which can be referred to as a fuel cell stack, to generate a desired voltage. Fuel cells can include solid oxide fuel cells (SOFCs), molten carbonate fuel cells (MCFCs), phosphoric acid fuel cells (PAFCs), and proton exchange membrane fuel cells (PEMFCs), which are generally named after their respective electrolytes.

[0083] It will be appreciated that, in at least certain example embodiments, the fuel cell stacks 232, 234 can extend substantially 360 degrees in the circumferential direction C of the gas turbine engine (i.e., the direction extending about the centerline axis 101 of the gas turbine engine 100). For example, referring now to Figure 3 , a cross-sectional cutaway perspective view of a fuel cell stack 232 according to example embodiments of the present disclosure is depicted. Additional fuel cell assemblies described in greater detail below can be constructed in a similar manner.

[0084] As shown, the fuel cell stack 232 extends in the circumferential direction C around the outer liner 210 of the combustion chamber 228, in the illustrated embodiment, completely surrounding the outer liner 210 of the combustion chamber 288 about the centerline axis 101. More specifically, the fuel cell stack 232 (e.g., a plurality of fuel cells coupled together referred to as a fuel cell stack) is arranged in the circumferential direction C. In Figure 3The fuel cells of the fuel cell stack 232 visible in FIG. 1 can be arranged as a single ring or cylinder. As described in further detail below, the fuel cell stack 232 can have a thickness relative to the axial direction A (see FIG. 1). In another example, multiple additional rings of fuel cells can be placed on top of one another or outside of one another (e.g., radially stacked or arranged concentrically) to form the fuel cell stack 232 having an elongated length in the radial direction R. Figure 2

[0085] As will be explained in further detail below, with reference to Figure 4 , the fuel cell stack 232 is positioned to receive the exhaust air 244 from, for example, the compressor section and the fuel 246 from the fuel delivery system 146. The fuel cell stack 232 can include a channel 247 around the outside of the fuel cell stack 232. The channel 247 receives the air 244 and the fuel 246 and directs and distributes the air 244 and the fuel 246 around the outer surface of the fuel cell stack 232 and into the fuel cell stack 232.

[0086] In the case of the fuel cell stack 234, the channel 247 is around the inside of the fuel cell stack 234. Here, the channel 247 receives the air 244 and the fuel 246 and directs and distributes the air 244 and the fuel 246 around the inner surface of the fuel cell stack 234 and into the fuel cell stack 234.

[0087] The fuel cell stack 232 uses the air 244 and at least some of the fuel 246 to generate an electrical current and directs partially oxidized fuel and unused portions of air (e.g., output product 248) radially into the combustion chamber 228 (see FIG. 1). The burner 206 (see FIG. 1) combusts the partially oxidized fuel and air (e.g., output product 248) in the combustion chamber 228 into combustion gases that are directed downstream into the turbine section to drive or assist in driving one or more turbines therein. Figure 2 Figure 2

[0088] Figure 3 The fuel cell stack 232 depicted in FIG. 1 can include a housing 250 having a combustion outlet side 252 and a fuel and air inlet side 254 opposite the combustion outlet side 252, as well as sides 256, 258. The side 258 is not visible in the perspective view of FIG. 1. Figure 3

[0089] It will be appreciated that, alternatively, the fuel cell stack 232 can include multiple fuel cell stacks, for example, stacked side-by-side or concentrically.

[0090] ​​​​The combustion outlet side 252 includes a plurality of combustion outlets 264, and the fuel and air inlet side 254 includes a plurality of fuel and air inlets 266. In the case where the fuel cell stack 232 is integrated with the liner of the combustion chamber 228, the combustion outlet side 252 can be the outer liner 210 of the combustion chamber 228. Alternatively, the outer liner 210 of the combustion chamber can have an opening 271, and the output product 248 directed out of the combustion outlets 264 is directed to move through the opening 271 and into the combustion chamber 228.

[0091] The trench 247 includes one or more fuel inlets 268 and one or more air inlets 270. Optionally, one or more of the inlets 268, 270 can be on the other side of the housing 250. Each of the one or more fuel inlets 268 is fluidly coupled with a source of fuel for the fuel cell stack 232, such as a hydrogen-containing gas or one or more pressurized containers of a fuel handling unit described further below. Each of the one or more air inlets 270 is fluidly coupled with a source of air for the fuel cell stack 232, such as air exhausted from a compressor section and / or an air handling unit described further below. The inlets 268, 270 separately receive fuel and air from external sources of fuel and air, and separately direct the fuel and air into the fuel cell stack 232.

[0092] During operation, the trench 247 receives the air 244 and the fuel 246, and directs and distributes the air 244 and the fuel 246 around the fuel and air inlet side 254 of the fuel cell stack 232, and through the fuel and air inlets 266 into the fuel cell stack 232. The fuel cell stack 232 generates output products and output product 248 (e.g., partially oxidized fuel and air), also referred to herein as “combustion gas.” The output product 248 is generated using fuel and air that is not consumed by the fuel cells 204.

[0093] The output product 248 is directed out of the combustion outlet side 252 of the housing 250 from the combustion outlets 264, for example through an opening 271 in the liner of the combustion chamber 228. The output product 248 is provided to the combustion chamber 228, and combusted during operation to generate combustion gas that is used to generate thrust for the gas turbine engine 100 (and a carrier / aircraft incorporating the gas turbine engine 100).

[0094] In certain example embodiments, the fuel cell stack 232 can be configured in a similar manner as one or more of the example fuel cell systems (labeled 108) described in U.S. Patent Application Publication No. 2019 / 0136761 Al, filed November 7, 2017, the entire contents of which are incorporated herein by reference.

[0095] In certain example embodiments, the fuel cell stack 242 can be constructed in a manner similar to one or more of the example fuel cell systems (labeled 100) described in U.S. Patent Application Publication No. 2020 / 0194799 Al, filed December 17, 2018, the entire contents of which are incorporated herein by reference.

[0096] Reference will now be made to Figure 4 Operation of the integrated fuel cell and combustor assembly 200 according to example embodiments of the present disclosure will be described. More specifically, Figure 4 A schematic view of a gas turbine engine 100 and an integrated fuel cell and combustor assembly 200 according to embodiments of the present disclosure is provided. In certain example embodiments, the gas turbine engine 100 and the integrated fuel cell and combustor assembly 200 can be constructed in a manner similar to one or more of the example gas turbine engines described in U.S. Patent Application Publication No. 2020 / 0194799 Al, filed December 17, 2018, the entire contents of which are incorporated herein by reference. Figures 1-3

[0097] Accordingly, it will be appreciated that the gas turbine engine 100 generally includes a fan section 102 having a fan 126, an LP compressor 110, an HP compressor 112, a combustion section 114, an HP turbine 116, and an LP turbine 118. The combustion section 114 generally includes an integrated fuel cell and combustor assembly 200 having a combustor 206 and a fuel cell assembly 204.

[0098] The propulsion system including the gas turbine engine 100 further includes a fuel delivery system 146. The fuel delivery system 146 generally includes a fuel source 148 and one or more fuel delivery lines 150. The fuel source 148 can include a supply of fuel (e.g., a hydrocarbon fuel, including, for example, a carbon neutral fuel or a synthetic hydrocarbon) for the gas turbine engine 100. Further, it will be appreciated that the fuel delivery system 146 further includes a fuel pump 272 and a flow splitter 274, and the one or more fuel delivery lines 150 include a first fuel delivery line 150A, a second fuel delivery line 150B, and a third fuel delivery line 15C.

[0099] The flow splitter 274 splits the fuel flow from the fuel source 148 and the fuel pump 272 into a first fuel flow through the first fuel delivery line 150A to the fuel cell assembly 204 (and, in particular, to a fuel processing unit described below), a second fuel flow through the second fuel delivery line 150B also to the fuel cell assembly 204 (and, in particular, to an air processing unit described below), and a third fuel flow through the third fuel delivery line 150C to the combustor 206.

[0100] ​The flow splitter 274 can include a series of valves (not shown) to facilitate such splitting of the fuel flow from the fuel source 148, or alternatively can have a fixed geometry. Further, for the illustrated embodiment, the fuel delivery system 146 includes a first fuel valve 151 A associated with the first fuel delivery line 150A (e.g., to control the first fuel flow), a second fuel valve 151 B associated with the second fuel delivery line 150B (e.g., to control the second fuel flow), and a third fuel valve 151 C associated with the third fuel delivery line 150C (e.g., to control the third fuel flow).

[0101] The gas turbine engine 100 further includes a compressor bleed system and an airflow delivery system. More specifically, the compressor bleed system includes an LP bleed air duct 276 and an associated LP bleed air valve 278, an HP bleed air duct 280 and an associated HP bleed air valve 282, an HP outlet air duct 284 and an associated HP outlet air valve 286.

[0102] The gas turbine engine 100 further includes an airflow supply duct 288 (in airflow communication with an airflow supply 290) and an associated air valve 292, which is also in airflow communication with the airflow delivery system, for providing compressed airflow to the fuel cell assembly 204 of the integrated fuel cell and combustor assembly 200. The airflow supply can be, for example, a second gas turbine engine configured to provide cross-bleed air, an auxiliary power unit (APU) configured to provide bleed air, a ram air turbine (RAT), etc. The airflow supply can be a supplement to the compressor bleed system if the compressor air source is insufficient or unavailable.

[0103] The compressor bleed system (and the airflow supply duct 288) is in airflow communication with the airflow delivery system for providing compressed airflow to the fuel cell assembly 204, as will be explained in greater detail below.

[0104] Still referring to Figure 4 The fuel cell assembly 204 of the integrated fuel cell and combustor assembly 200 includes a fuel cell stack 232, which can be configured in a similar manner as, for example, the fuel cell stack 232 described above. The fuel cell stack 232 is schematically depicted as a single fuel cell having a cathode side 296, an anode side 298, and an electrolyte 300 positioned therebetween. It will be generally understood that the electrolyte 300 can conduct negative oxygen ions from the cathode side 296 to the anode side 298 during operation to generate an electrical current and electrical power.

[0105] Anode side 298 can support electrochemical reactions that generate electricity. Fuel can be oxidized in anode side 298 using oxygen ions received from cathode side 296 via diffusion through electrolyte 300. This reaction can produce heat, steam, and electricity in the form of free electrons in anode side 298, which can be used to power energy consuming devices, such as one or more additional electrical devices 328 described below. Oxygen ions can be generated using electrons returned to cathode side 296 from the energy consuming devices via oxygen reduction of the cathode oxidant.

[0106] Cathode side 296 can be coupled to a source of cathode oxidant, such as oxygen in the atmosphere. Cathode oxidant is defined as the oxidant supplied to cathode side 296 that the fuel cell system uses when generating electricity. Cathode side 296 can be permeable to oxygen ions received from the cathode oxidant.

[0107] Electrolyte 300 can be in communication with anode side 298 and cathode side 296. Electrolyte 300 can pass oxygen ions from cathode side 296 to anode side 298 and can have little or no electrical conductivity to prevent free electrons from passing from cathode side 296 to anode side 298.

[0108] An anode side of a solid oxide fuel cell, such as fuel cell stack 232, can be composed of nickel / yttria stabilized zirconia (Ni / YSZ) cermet. The nickel in the anode side acts as a catalyst for fuel oxidation and as a current conductor. During normal operation of fuel cell stack 232, the operating temperature can be greater than or equal to about 700°C, and the nickel (Ni) in the anode retains its reduced form due to the continuous supply of primarily hydrogen fuel gas. Other configurations can also be contemplated.

[0109] Briefly, it will be understood that fuel cell assembly 204 further includes a fuel cell sensor 302 configured to sense data indicative of a fuel cell assembly operating parameter, such as a temperature of fuel cell stack 232 (e.g., a cathode side 296 or an anode side 298 of a fuel cell), a pressure within fuel cell stack 232 (e.g., within a cathode side 296 or an anode side 298 of a fuel cell).

[0110] Fuel cell stack 232 is disposed downstream of LP compressor 110, HP compressor 112, or both. Further, from the above regarding Figure 2As will be understood from the description, fuel cell stack 232 may be coupled to or otherwise integrated with the bushing of burner 206 (e.g., the outer liner 210 or inner liner 208 for fuel cell stack 234). In this way, fuel cell stack 232 may also be arranged upstream of combustion chamber 228 of integrated fuel cell and burner assembly 200, and further upstream of HP turbine 116 and LP turbine 118.

[0111] like Figure 4 As shown, the fuel cell assembly 204 also includes a fuel processing unit 304 (e.g., a fuel and air premixing device) and an air processing unit 306. In the exemplary embodiment depicted, the fuel processing unit 304 and the air processing unit 306 are manifolded together within the housing 308 to provide conditioned air and fuel to the fuel cell stack 232.

[0112] The fuel processing unit 304 can be any suitable structure for generating a hydrogen-rich fuel stream. For example, the fuel processing unit 304 may include a fuel reformer or a catalytic partial oxidation converter (CPO). x ), used to generate a hydrogen-rich fuel stream for fuel cell stack 232.

[0113] However, it should be understood that the fuel processing unit 304 may additionally or alternatively include any suitable type of fuel reformer, such as an automatic thermal reformer and a steam reformer, which may require an additional steam inlet flow with a higher hydrogen composition at the reformer outlet flow. Additionally or alternatively, the fuel processing unit 304 may also include a reformer integrated with the fuel cell stack 232.

[0114] The air handling unit 306 can be any suitable structure for raising the temperature of the air supplied to it to a temperature sufficiently high to achieve fuel cell temperature control (e.g., about 600°C to about 800°C). For example, in the depicted embodiment, the air handling unit includes a pre-burner system that operates based on a fuel flow through a second fuel delivery line 150B and is configured to raise the temperature of the air by combustion, for example, during transient conditions such as start-up, shutdown, and abnormal situations.

[0115] Similarly, it should be understood that Figure 4 The air handling unit 306 may alternatively be a heat exchanger or another device for raising the temperature of the air supplied thereto to a temperature high enough to achieve fuel cell temperature control (e.g., about 600°C to about 800°C).

[0116] As described above, the compressor discharge system (and air supply duct 288) is in airflow communication with the airflow delivery system for supplying compressed airflow to the fuel cell assembly 204. The airflow delivery system includes an anode airflow duct 310 and associated anode airflow valve 312 for supplying airflow to the fuel processing unit 304, a cathode airflow duct 314 and associated cathode airflow valve 316 for supplying airflow to the air processing unit 306, and a cathode bypass air duct 318 and associated cathode bypass air valve 320 for supplying airflow directly to the fuel cell stack 232 (or more precisely, to the cathode side 296 of the fuel cell).

[0117] The fuel delivery system 146 is configured to provide a first fuel flow to the fuel processing unit 304 via a first fuel delivery line 150A, and to provide a second fuel flow to the air processing unit 306 via a second fuel delivery line 150B (e.g., as fuel for the pre-combustion system, if provided).

[0118] The fuel cell stack 232 outputs electricity generated as fuel cell power output 322. In addition, the fuel cell stack 232 directs cathode air emissions and anode fuel emissions (e.g., output products, which are not labeled for clarity) into the combustion chamber 228 of the burner 206.

[0119] In operation, the air treatment unit 306 is configured to heat / cool a portion of the compressed air entering through the cathode airflow duct 314 to generate treated air to be directed into the fuel cell stack 232, thereby facilitating the operation of the fuel cell stack 232. The air treatment unit 306 receives a second fuel flow from the second fuel delivery line 150B and can, for example, combust this second fuel flow to heat the received air to a desired temperature (e.g., about 600°C to about 800°C), thereby facilitating the operation of the fuel cell stack 232. The air treated by the air treatment unit 306 is directed into the fuel cell stack 232. In embodiments of this disclosure, as shown, the cathode bypass air duct 318 and the air treated by the air treatment unit 306 can be combined into a combined airflow to be fed into the cathode 296 of the fuel cell stack 232.

[0120] In addition, such as Figure 4 As shown in the embodiment, a first fuel flow via a first fuel delivery line 150A is directed to a fuel processing unit 304 for generating a hydrogen-rich fuel flow (e.g., optimizing the hydrogen content of the fuel flow), which is also fed into the fuel cell stack 232. It will be understood, and discussed below, that the air (processing air and bypass air) flow to the fuel cell stack 232 (e.g., cathode side 296) and the fuel from the fuel processing unit 304 to the fuel cell stack 232 (e.g., anode side 298) can facilitate power generation.

[0121] Since the inlet air for the fuel cell stack 232 can only come from the upstream compressor section without any other separately controlled air source, it will be appreciated that the inlet air for the fuel cell stack 232 that is discharged from the compressor section will be subject to air temperature variations that occur during different flight phases. By way of illustrative example only, air within a particular location in the compressor section of the gas turbine engine 100 can work at 200°C during idle, 600°C during takeoff, 268°C during cruise, etc. This type of temperature variation in the inlet air directed to the fuel cell stack 232 can cause significant thermal transient issues (or even thermal shock) in the ceramic materials of the fuel cell stack 232 that can range from cracking to failure.

[0122] Accordingly, by fluidly connecting the air handling unit 306 between the compressor section and the fuel cell stack 232, the air handling unit 306 can be used as a control device or system to maintain the air that is handled by the air handling unit 306 and directed into the fuel cell stack 232 within a desired operating temperature range (e.g., plus or minus 100°C, or preferably plus or minus 50°C, or plus or minus 20°C). In operation, the temperature of the air provided to the fuel cell stack 232 (relative to the temperature of the air discharged from the compressor section) can be controlled by controlling the fuel flow to the air handling unit 306. By increasing the fuel flow to the air handling unit 306, the temperature of the airflow to the fuel cell stack 232 can be increased. By decreasing the fuel flow to the air handling unit 306, the temperature of the airflow to the fuel cell stack 232 can be decreased. Alternatively, no fuel can be delivered to the air handling unit 306 to prevent the air handling unit 306 from increasing and / or decreasing the temperature of the air that is discharged from the compressor section and directed into the air handling unit 306.

[0123] Further, as depicted in dashed lines, the fuel cell assembly 204 further includes an airflow bypass conduit 321 that extends around the fuel cell stack 232 to allow a portion or all of the airflow that is conditioned by the air handling unit 306 (and combined with any bypass air through conduit 318) to bypass the cathode side 296 of the fuel cell stack 232 and directly enter the combustor 228. The airflow bypass conduit 321 can be in thermal communication with the fuel cell stack 232. The fuel cell assembly further includes a fuel bypass conduit 323 that extends around the fuel cell stack 232 to allow a portion or all of the reforming fuel from the fuel handling unit 304 to bypass the anode side 298 of the fuel cell stack 232 and directly enter the combustor 228.

[0124] As briefly mentioned above, the fuel cell stack 232 converts the anode fuel stream from the fuel processing unit 304 and the air processed by the air processing unit 306 sent to the fuel cell stack 232 into electrical energy in the form of DC current, i.e., a fuel cell power output 322. This fuel cell power output 322 is directed to the power converter 236 to convert this DC current into DC or AC current that can be effectively utilized by one or more subsystems.

[0125] For the depicted embodiment, power is provided from the power converter to an electrical bus 326. The electrical bus 326 can be an electrical bus dedicated to the gas turbine engine 100, an electrical bus of an aircraft incorporating the gas turbine engine 100, or a combination thereof. The electrical bus 326 is in electrical communication with one or more additional electrical devices 328 that can be adapted to draw current from the fuel cell stack 294 or apply an electrical load to the fuel cell stack 232.

[0126] The one or more additional electrical devices 328 can be a power source, a power sink, or both. For example, the additional electrical devices 328 can be an electrical storage device (such as one or more batteries), an electrical machine (a generator, an electric motor, or both), an electrical propulsion device, etc. For example, the one or more additional electrical devices 328 can include a starter motor / generator of the gas turbine engine 100.

[0127] Still referring to Figure 4 , the gas turbine engine 100 further includes a sensor 330. In the depicted embodiment, the sensor 330 is structured to sense data indicative of a flame within the combustion section 114 of the gas turbine engine 100. For example, the sensor 330 can be a temperature sensor structured to sense data indicative of an exit temperature of the combustion section 114, an inlet temperature of the turbine section, an exhaust temperature, or a combination thereof. Additionally or alternatively, the sensor 330 can be any other suitable sensor or any suitable combination of sensors structured to sense one or more gas turbine engine operating conditions or parameters, including data indicative of a flame within the combustion section 114 of the gas turbine engine 100.

[0128] Further, as Figure 4 further illustratively depicted, the propulsion system, an aircraft including the propulsion system, or both include a controller 240. For example, the controller 240 can be a standalone controller, a gas turbine engine controller (e.g., a full authority digital engine controller or FADEC controller), an aircraft controller, a supervisory controller of the propulsion system, a combination thereof, etc.

[0129] The controller 240 is operatively connected to various sensors, valves, etc. within at least one of the gas turbine engine 100, the fuel delivery system 146, and the fuel cell and combustor assembly 200. More particularly, for the depicted example aspect, the controller 240 is operatively connected to the air handling unit 306, the fuel handling unit 304, the power converter 236 (and / or the power converter 238), valves of the axially distributed fuel cell stacks (e.g., air and fuel valves to the fuel cell stacks discussed below), valves of the compressor discharge system (valves 278, 282, 286), valves of the airflow delivery system (valves 312, 316, 320), and valves of the fuel delivery system 146 (splitter 274, valves 151A, 151B, 151C), as well as the gas turbine engine sensors 330 and the fuel cell sensors 302.

[0130] As will be appreciated from the following description, the controller 240 can be in wired or wireless communication with these components. In this manner, the controller 240 can receive data from various inputs (including the supervisory controller 412, the gas turbine engine sensors 330, and the fuel cell sensors 302 shown in FIG. 4), can make control decisions, and can provide data (e.g., instructions) to various outputs (including valves of the compressor discharge system that control the discharge of airflow from the compressor section, the airflow delivery system that directs the airflow discharged from the compressor section, and the fuel delivery system 146 that directs the flow of fuel within the gas turbine engine 100). Figure 4

[0131] With particular reference to the operation of the controller 240, in at least certain embodiments, the controller 240 can include one or more computing devices 332. The computing device(s) 332 can include one or more processor(s) 332A and one or more memory device(s) 332B. The processor(s) 332A can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and / or other suitable processing devices. The memory device(s) 332B can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and / or other memory devices.

[0132] ​One or more memory devices 332B can store information accessible by the one or more processors 332A, including computer-readable instructions 332C that can be executed by the one or more processors 332A. Instructions 332C can be any set of instructions that when executed by the one or more processors 332A, cause the one or more processors 332A to perform operations. In some embodiments, instructions 332C can be executed by the one or more processors 332A to cause the one or more processors 332A to perform operations such as any operations and functionalities the controller 240 and / or computing device 332 are structured to perform, operations for operating a propulsion system as described herein, and / or any other operations or functionalities of the one or more computing devices 332. Instructions 332C can be software written in any suitable programming language or can be implemented in hardware.

[0133] Additionally or alternatively, instructions 332C can be executed in logically and / or virtually separate threads on processor 332A. Memory devices 332B can further store data 332D that is accessible to the processors 332A. For example, data 332D can include data indicative of power flow, data indicative of gas turbine engine 100 / aircraft operating conditions, and / or any other data and / or information described herein.

[0134] Computing device 332 also includes a network interface 332E structured to communicate, for example, with other components of gas turbine engine 100 such as valves of the compressor discharge system (valves 278, 282, 286), valves of the air flow delivery system (valves 312, 316, 320), and valves of the fuel delivery system 146 (splitter 274, valves 151A, 151B, 151C), as well as sensors 330 of gas turbine engine 100 and fuel cell sensors 302, in conjunction with an aircraft incorporating gas turbine engine 100, etc.

[0135] Network interface 332E can include any suitable components for interfacing with one or more networks, including for example, transmitters, receivers, ports, controllers, antennas, and / or other suitable components. In this manner, it will be understood that network interface 332E can utilize any suitable combination of wired and / or wireless communication networks.

[0136] The technology discussed herein makes reference to computer-based systems, actions taken by and information sent to and from computer-based systems. It is understood that the inherent flexibility of computer-based systems allows for a great variety of possible configurations, combinations, and divisions of tasks and functionality between and among components. For instance, 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 across multiple systems. Distributed components can operate sequentially or in parallel.

[0137] As briefly described above, the fuel cell assembly 204 can be in electrical communication with an electrical bus 326, which can be an electrical bus of the gas turbine engine 100, an electrical bus of the aircraft, or a combination thereof. Referring now briefly to Figure 5 A schematic view of an aircraft 400 including one or more gas turbine engines 100 (labeled 100A and 100B), each having an integrated fuel cell and combustor assembly 200 (labeled 200A and 200B), and an aircraft electrical bus 326 in electrical communication with the one or more gas turbine engines 100, is provided in accordance with embodiments of the present disclosure.

[0138] For the example embodiments described, the aircraft 400 includes a fuselage 402, a tail 404, a first wing 406, a second wing 408, and a propulsion system. The propulsion system generally includes a first gas turbine engine 100A coupled to or integrated with the first wing 406 and a second gas turbine engine 100B coupled to or integrated with the second wing 408. However, it will be understood that any other suitable number and / or configuration of gas turbine engines 100 (e.g., mounted on the fuselage, mounted on the tail, etc.) can be provided in other embodiments.

[0139] The first gas turbine engine 100A generally includes a first integrated fuel cell and combustor assembly 200A and a first electric machine 410A. The first integrated fuel cell and combustor assembly 200A can generally include a first fuel cell assembly. The first electric machine 410A can be an embedded electric machine, a bias electric machine (e.g., capable of rotating with the gas turbine engine 100 through an accessory gearbox or suitable gear train), etc. For example, in certain example embodiments, the first electric machine 410A can be a starter motor / generator of the first gas turbine engine 100A.

[0140] Similarly, the second gas turbine engine 100B generally includes a second integrated fuel cell and combustor assembly 200B and a second electric machine 410B. The second integrated fuel cell and combustor assembly 200B can generally include a second fuel cell assembly. The second electric machine 410B can also be an embedded electric machine, an offset electric machine (e.g., capable of rotating with the gas turbine engine 100B through an accessory gearbox or suitable gear train), or the like. For example, in certain example embodiments, the second electric machine 410B can be a starter motor / generator of the second gas turbine engine 100B.

[0141] In Figure 5 embodiments, the aircraft 400 additionally includes an electrical bus 326 and a supervisory controller 412. Further, it will be appreciated that the aircraft 400 and / or propulsion system includes one or more electrical devices 414 and an electrical energy storage unit 416 each in electrical communication with the electrical bus 326. The electrical devices 414 can represent one or more aircraft power loads (e.g., avionics systems, control systems, electric propulsors, etc.), one or more power sources (e.g., auxiliary power units), or the like. The electrical energy storage unit 416 can be, for example, a battery pack or the like for storing electrical power.

[0142] The electrical bus 326 is further electrically connected to the first electric machine 410A and the first fuel cell assembly, and to the second electric machine 410B and the second fuel cell assembly. The supervisory controller 412 can be configured in a similar manner as the controller 240 of Figure 4 or can be in operative communication with a first gas turbine engine controller specific to the first gas turbine engine 100A and a second gas turbine engine controller specific to the second gas turbine engine 100B.

[0143] In this manner, it will be appreciated that the supervisory controller 412 can be configured to receive data from the gas turbine engine sensors 330A of the first gas turbine engine 100A and from the gas turbine engine sensors 330B of the second gas turbine engine 100B, and can be further configured to send data (e.g., commands) to various control elements (such as valves) of the first and second gas turbine engines 100A, 100B.

[0144] Further, it will be appreciated that, for the depicted embodiments, the aircraft 400 includes one or more aircraft sensors 418 configured to sense data indicative of various flight operations of the aircraft 400, including, for example, altitude, ambient temperature, ambient pressure, airspeed, etc. The supervisory controller 412 is operatively connected to these aircraft sensors 418 to receive data therefrom.

[0145] In addition to receiving data from sensors 330A, 330B, 418 and sending data to control elements, supervisory controller 412 is structured to control power flow through electrical bus 326. For example, supervisory controller 412 can be structured to command and receive a desired power draw from one or more electric machines (e.g., first electric machine 410A and second electric machine 410B), one or more fuel cell assemblies (e.g., first fuel cell assembly and second fuel cell assembly), or both, and provide all or a portion of the drawn power to the other or both of the one or more electric machines (e.g., first electric machine 410A and second electric machine 410B), one or more fuel cell assemblies (e.g., first fuel cell assembly and second fuel cell assembly). One or more of these actions can be performed in accordance with the logic outlined below.

[0146] Reference will be made to Figure 6 and 7 An integrated fuel cell and combustor assembly 200 according to two example embodiments of the present disclosure will be described.

[0147] Reference will be made first in particular to Figure 6 A plurality of fuel cell stacks 232 extend around or are integrated into an outer liner 210 that defines a combustion chamber 228. The plurality of fuel cell stacks 232 are distributed along an axial direction A and independently receive air 244 from an air handling unit 306 and fuel 246 from a fuel handling unit 304.

[0148] In Figure 6 a first fuel cell stack 232A of the plurality of fuel cell stacks 232 is connected to the air handling unit 306 by a first air line that includes a valve and to the fuel handling unit 304 by a first fuel line that includes a valve; a second fuel cell stack 232B of the plurality of fuel cell stacks 232 is connected to the air handling unit 306 by a second air line that includes a valve and to the fuel handling unit 304 by a second fuel line that includes a valve; a third fuel cell stack 232C of the plurality of fuel cell stacks 232 is connected to the air handling unit 306 by a third air line that includes a valve and to the fuel handling unit 304 by a third fuel line that includes a valve; a fourth fuel cell stack 232D of the plurality of fuel cell stacks 232 is connected to the air handling unit 306 by a fourth air line that includes a valve and to the fuel handling unit 304 by a fourth fuel line that includes a valve; and a fifth fuel cell stack 232E of the plurality of fuel cell stacks 232 is connected to the air handling unit 306 by a fifth air line that includes a valve and to the fuel handling unit 304 by a fifth fuel line that includes a valve. In this embodiment, the various air lines, fuel lines, and valves are not labeled for clarity.

[0149] Because the fuel and air flow (e.g., flow rate) to the fuel cell stacks 232A, 232B, 232C, 232D, 232E is independently controllable (e.g., by a controller 240, which can be operably coupled to the various valves, not shown), the output product 248 from the fuel cell stacks 232A, 232B, 232C, 232D, 232E along the axial length of the combustor 206 Figure 3 ) is configured to be controlled to achieve an axial temperature profile to reduce emissions by a “late lean” method or the like. For example, the fuel cell stacks 232A, 232B, 232C, 232D, 232E can be independently controllable to control the volume and composition (e.g., % H2) of the output product 248 within the combustion chamber 228 along the axial length of the combustor 206 to affect the axial temperature profile therein, thereby reducing emissions by a “late lean” combustion method.

[0150] The plurality of fuel stacks 232 in the axial profile are configured to achieve at least one of a late lean injection and a desired combustor gas concentration profile. For example, the gas concentration profile can be along the axial direction, along the circumferential direction, or a combination of both.

[0151] The controlled gas composition profile can include an emissions indicator including at least one of CO, carbon dioxide (CO2), water vapor (H2O), unburned hydrocarbons (UHC), particulate matter (e.g., primarily carbon), NO x and excess atmospheric oxygen and nitrogen.

[0152] It will be appreciated that in the depicted embodiment, each of the fuel cell stacks 232A, 232B, 232C, 232D, 232E is configured to receive an air flow from the same air handling unit 306 and a fuel flow from the same fuel handling unit 304. However, in alternative example embodiments, the illustrated fuel cell system can include more than one air handling unit 306, more than one fuel handling unit 304, or both. In such example embodiments, the fuel cell system can be configured to provide an air flow to one of the fuel cell stacks 232A, 232B, 232C, 232D, 232E at a higher or lower temperature, pressure, flow rate, or combination thereof than the other fuel cell stacks 232A, 232B, 232C, 232D, 232E; can be configured to provide a fuel flow to one of the fuel cell stacks 232A, 232B, 232C, 232D, 232E at a higher or lower temperature, pressure, flow rate, or combination thereof than the other fuel cell stacks 232A, 232B, 232C, 232D, 232E. This can facilitate a greater degree of control over the axial temperature profile through the combustion chamber 228.

[0153] Although spacing is provided between fuel cell stacks 232A, 232B, 232C, 232D, 232E for illustrative purposes, fuel cell stacks 232A, 232B, 232C, 232D, 232E can completely cover the liner of combustion chamber 228 along the length of combustor 206 in axial direction A.

[0154] In alternative embodiments described in greater detail below, different fuel cell stacks 232 can extend along different lengths in axial direction A. In some embodiments, fuel cell stacks 232 partially cover liner 208, 210 defining combustion chamber 228 along the length of combustor 206 in axial direction A.

[0155] In alternative embodiments described in greater detail below, different fuel cell stacks 232 can have different sizes (represented by height in radial direction R). Here, the size of fuel cell stacks 232 generally corresponds to a greater potential for generating electrical power for a given number of individual fuel cells and fuel cell stacks, and a greater potential for flow rate of output products 248 therethrough to combustion chamber 228.

[0156] Still referring to Figure 6 , the depicted exemplary fuel cell system further includes a plurality of fuel cell stacks 234A, 234B, 234C, 234D, 234E.

[0157] Here, however, the plurality of fuel cell stacks 234A, 234B, 234C, 234D, 234E extend around housing 220 of combustor 206 or are integrated into inner liner 208 of combustor 206. The plurality of fuel cell stacks 234A, 234B, 234C, 234D, 234E are distributed along axial direction A and are connected one after another in a cascading arrangement (e.g., a serial flow arrangement) by connections 440, 442, 444, 446. Here, fuel 246 (see Figure 6 ) received at a first fuel cell stack 234A of the plurality of fuel cell stacks 234A, 234B, 234C, 234D, 234E in embodiments of the present disclosure from fuel processing unit 304 (see Figure 3 ) (and / or air 244 (see Figure 3 ) from air processing unit 306) is configured to be provided to another fuel cell stack 234B of the plurality of fuel cell stacks 234A, 234B, 234C, 234D, 234E in embodiments of the present disclosure via connections 440, 442, 444, 446. Figure 6

[0158] ​The connections can be configured to control flow from one fuel cell stack 232 to the next. For example, the size of the grooves of each of the connections 440, 442, 444, 446 can be reduced to reduce the amount of flow through the grooves. In addition, the connections 440, 442, 444, 446 can include valves configured to be controlled to control flow from one fuel cell stack 232 to the next.

[0159] In Figure 6 , the first fuel cell stack 234A is connected to the fuel processing unit 304 by the first fuel flow line 448; the second fuel cell stack 234B is connected to the first fuel cell stack 234A by the connection 440; the third fuel cell stack 234C is connected to the second fuel cell stack 234B by the connection 442; the fourth fuel cell stack 234D is connected to the third fuel cell stack 234C by the connection 444; and the fifth fuel cell stack 234E is connected to the fourth fuel cell stack 234D by the connection 446.

[0160] For example, the grooves 247( Figure 3 ) of the fuel cell stacks 234 can be connected by the connections 440, 442, 444, 446.

[0161] Although not depicted, it will be appreciated that in at least certain example embodiments, the fuel cell system can be similarly configured to provide air flow to multiple fuel cell stacks 234A, 234B, 234C, 234D, 234E in a similar cascading manner.

[0162] It will be appreciated that such a configuration provides control and distribution of the output products 248( Figure 3 ) from the multiple fuel cell stacks 234A, 234B, 234C, 234D, 234E along the length of the combustor 206 in the axial direction A.

[0163] Now referring in particular to Figure 7 , the multiple fuel cell stacks 232A, 232B extend around, or are integrated into, the outer liner 210 defining the combustion chamber 228. The multiple fuel cell stacks 232 are distributed along the axial direction A and independently receive air 244( Figure 3 ) from the air processing unit 306 and fuel 246( Figure 3 ) from the fuel processing unit 304.

[0164] In Figure 7In the example embodiment, a first fuel cell stack 232A of the plurality of fuel cell stacks 232 is connected to the air handling unit 306 by a first air flow line 500 including a valve 502 and to the fuel handling unit 304 by a first fuel flow line 504 including a valve 506; and a second fuel cell stack 232B of the plurality of fuel cell stacks 232 is connected to the air handling unit 306 by a second air flow line 510 including a valve 512 and to the fuel handling unit 304 by a second fuel flow line 514 including a valve 516.

[0165] Here, the first fuel cell stack 232A covers a greater length of the outer liner 210 defining the combustion chamber 228 in the axial direction A than the second fuel cell stack 232B. More specifically, the first fuel cell stack 232A has a greater length in the axial direction A than the second fuel cell stack 232B.

[0166] For example, the length of the first fuel cell stack 232A along the axial direction A can be at least about 5% greater than the length of the second fuel cell stack 232B along the axial direction A, such as at least about 10% greater, such as at least about 20% greater, such as at least about 25% greater, such as at least about 40% greater, such as at least about 60% greater, such as up to about 1,000% greater.

[0167] Further, for the depicted embodiment, the first fuel cell stack 232A is upstream of the second fuel cell stack 232B, and the second fuel cell stack 232B is positioned to be at, adjacent, proximate, near, etc. a downstream end 526 of the combustion chamber 228 in the axial direction A (i.e., the most downstream location of the combustion chamber 228 along the axial direction A). For example, an upstream end of the second fuel cell stack 232B is spaced apart from an upstream end 520 of the combustion chamber 228 (i.e., the most upstream location of the combustion chamber 228 along the axial direction A, e.g., at the dome 212 or opening 229) by a distance 522. The second fuel cell stack 232B provides output products 248 to the combustion chamber 228 downstream of the distance 522 (e.g., at or adjacent the downstream end 526 of the combustion chamber 228). A length 528 of the combustion chamber 228 in the axial direction A can be measured between the upstream end 520 and the downstream end 526.

[0168] Since the fuel and air flow (e.g., flow rate) to the fuel cell stacks 232A, 232B is independently controlled by the controller 240, the output products 248A, 248B from the respective fuel cell stacks 232A, 232B along the length 528 of the combustor 206 can be controlled to achieve an axial temperature profile to reduce emissions by a “late lean” combustion method, etc.

[0169] For example, the controller 240 can increase the fuel flow rate to the second fuel cell stack 232B relative to the fuel flow rate (e.g., indicated by the longer output product 248 “arrow”) to the first fuel cell stack 232A to modify the composition of the output product 248, e.g., to increase the % H2 in the output product, resulting in an increase in downstream secondary combustion in the combustion chamber. This distribution or composition of the output product 248 can provide for more complete combustion of the combustion gases generated within the combustion chamber 228 and a reduction of certain emissions, such as NOx x ) emissions.

[0170] Additionally or alternatively, the controller 240 can control one or both of the power converters 238, 239 to increase the current drawn from the second fuel cell stack 232B. By increasing the current in the downstream fuel cell stack 232B, the fuel cell exhaust injected downstream into the combustor 206 tends to have less residual fuel than the fuel cell exhaust injected upstream into the combustor 206. Given the same amount of air flow rate to both the first and second fuel cell stacks 232A, 232B, this approach generates a higher air / fuel ratio (or lean combustion) at the downstream end of the combustor 206.

[0171] The controller 240 is configured to control the valves 506, 516 in cooperation with the power converters 238, 239 to achieve a desired combustor gas composition distribution.

[0172] The controller 240 is configured to control the valves 506, 516 in cooperation to achieve a desired combustor gas temperature distribution.

[0173] The controller 240 is configured to control the valves 506, 516 in cooperation to achieve a desired combustor gas pressure distribution.

[0174] Additionally or alternatively, the temperature of the output product 248B from the second fuel cell stack 232B can be increased to provide a desired effect on emissions within the combustion gases generated within the combustion chamber 228. For example, a higher temperature gas stream can be provided to the second fuel cell stack 232B to increase the temperature of the output product 248B therefrom.

[0175] It will be understood that, as described above with respect to Figure 6 , although Figure 7 each of the fuel cell stacks 232A, 232B depicted therein are configured to receive an air stream from the same air handling unit 306 and a fuel stream through the same fuel handling unit 304, in alternative example embodiments, the illustrated fuel cell system can include more than one air handling unit 306, more than one fuel handling unit 304, or both.

[0176] Further, it will be understood that, although for the example embodiments described above with respect toFigure 7 In one embodiment, the first fuel cell stack 232A (upstream fuel cell stack) has a longer axial dimension than the second fuel cell stack 232B (downstream fuel cell stack). However, in other exemplary embodiments, this configuration may be reversed, such that the downstream fuel cell stack has a longer axial dimension than the upstream fuel cell stack.

[0177] The distance 522 to the downstream section 524 can be at least 30% of the length 528 of the combustion chamber 228. For example, in some exemplary embodiments, the distance 522 can be greater than or equal to half the length 528 of the combustion chamber 228 in the axial direction A. For example, the distance 522 to the downstream section 524 can be at least two-thirds, at least three-fifths, or at least four-sevenths of the length 528 of the combustion chamber 228 in the axial direction A. This configuration ensures that the second fuel cell stack 232B is positioned to provide a desired amount of secondary downstream combustion / heat additive to the combustion gas within the combustion chamber 228 to influence undesirable components in the combustion gas (such as NO). x The amount of ).

[0178] Now for reference Figure 8 The following describes an integrated fuel cell and burner assembly 200 according to an additional exemplary embodiment of the present disclosure.

[0179] Figure 8 An exemplary integrated fuel cell and burner assembly 200 can be used with Figure 7 The exemplary integrated fuel cell and burner assembly 200 is constructed in a similar manner. For example, Figure 8 An exemplary integrated fuel cell and burner assembly 200 includes a fuel cell stack 232 that extends around or is integrated into a liner 210 defining a combustion chamber 228. The fuel cell stack 232 may receive air 244 from an air handling unit 306 and air from a fuel handling unit 304. Figure 8 Fuel 246 (not shown in the image).

[0180] The fuel cell stack 232 is positioned in the axial direction A at, adjacent to, near, or close to the downstream end 526 of the combustion chamber 228. The upstream end of the fuel cell stack 232 is spaced apart from the upstream end 520 of the combustion chamber 228 (e.g., dome 212 or opening 229) by a distance 522.

[0181] Here, fuel cell stack 232 is the foremost fuel cell stack 232.

[0182] In this embodiment, distance 522 represents a distance between an upstream location at which fuel is first provided to combustion chamber 228 (e.g., upstream end 520 in the depicted embodiment) through opening 229 and a downstream location at which fuel or output product is next provided to combustion chamber 228. Fuel cell stack 232 provides output product 248 to combustion chamber 228 downstream of distance 522 (e.g., at or adjacent downstream section 524 of combustion chamber 228 or downstream end 526). A length 528 of combustion chamber 228 can be measured in axial direction A between upstream end 520 and downstream end 526.

[0183] Distance 522 can be similar to distance 522 described above with respect to Figure 7 For example, distance 522 to downstream section 524 can be at least 30% of length 528 of combustion chamber 228. In certain example embodiments, distance 522 can be greater than or equal to one-half of length 528 of combustion chamber 228 in axial direction A. For example, distance 522 to downstream section 524 can be at least two-thirds, at least three- fifths, or at least seven-quarters of length 528 of combustion chamber 228 in axial direction A.

[0184] Distance 522 to downstream section 524 can be greater than or equal to one-half of length 528 of combustion chamber 228 in axial direction A. For example, distance 522 to downstream section 524 can be two-thirds, three-fifths, seven-quarters, etc. of length 528 of combustion chamber 228 in axial direction A.

[0185] Output product 248 from fuel cell stack 232 along a portion of the length of combustor 206 in axial direction A can be used to achieve a desired axial temperature profile, particularly within downstream section 524. Such a configuration can reduce emissions through a “late lean” combustion approach. For example, with less than 100% fuel utilization within fuel cell stack 232, output product 248 will include hydrogen (H2), which can promote a secondary downstream combustion within combustion chamber 228, potentially providing more complete combustion of combustion gases flowing therethrough.

[0186] Additionally, it will be appreciated that output product 248 can be provided to combustion chamber 228 at a relatively high temperature and can further include oxygen. The high temperature of output product 248 and the oxygen content of output product 248 can similarly promote more complete combustion of combustion gases flowing through combustion chamber 228. The above effects can potentially reduce undesirable components (e.g., NOx) in combustion gases from combustion chamber. x

[0187] ​In certain example embodiments, the controller 240 can modify a fuel flow rate to the fuel cell stack 232, an air flow rate to the fuel cell stack 232, a temperature of air provided to the fuel cell stack 232, a current drawn from the fuel cell stack 232, or a combination thereof, to modify a composition, a temperature, a flow rate, or a combination thereof, of the output product 248 provided to the combustion chamber 228, to, for example, promote more complete combustion of combustion gases within the combustion chamber 228 near or within the downstream section 524 of the combustion chamber 228.

[0188] According to example methods, an aviation fuel stream is provided to the combustion chamber 228 of the combustor 206 through the opening 229 defined at the upstream end 520 of the combustion chamber 228 to initiate initial combustion within the combustion chamber 228. Further, an output product stream 248 is provided from the fuel cell stack 232 to the combustion chamber 228 at the downstream section 524 of the combustion chamber 228 to initiate secondary combustion within the combustion chamber 228 at a downstream location of the initial combustion within the combustion chamber.

[0189] Reference will now be made to Figure 9 An example integrated fuel cell and combustor assembly 200 according to additional example embodiments of the present disclosure will be described.

[0190] Figure 9 The example integrated fuel cell and combustor assembly 200 of Figure 7 may be constructed in a similar manner as the example integrated fuel cell and combustor assembly 200 of Figure 9 The example integrated fuel cell and combustor assembly 200 includes a fuel cell stack 232 that extends around or is integrated into an outer liner 210 that defines a combustion chamber 228. The fuel cell stack 232 can receive air 244 from an air handling unit 306 and fuel 246 from a fuel handling unit 304 (not shown in FIG. 1) and provide an output product 248 to the combustion chamber 228. Figure 9

[0191] Figure 9 The fuel cell stack 232 of the example integrated fuel cell and combustor assembly 200 includes a first fuel cell stack 232A positioned at, adjacent to, proximate to, near, etc. the upstream end 520 of the combustion chamber 228 in the axial direction A and a second fuel cell stack 232B positioned at, adjacent to, proximate to, near, etc. the downstream end 526 of the combustion chamber 228 in the axial direction A. An upstream end of the second fuel cell stack 232B is spaced apart from the upstream end 520 of the combustion chamber 228 (e.g., the dome 212 or the opening 229) by a distance 522.

[0192] ​The first fuel cell stack 232A provides output products 248A to the combustion chamber 228 upstream of the distance 522, and the second fuel cell stack 232B provides output products 248B to the combustion chamber 228 downstream of the distance 522 (e.g., in the downstream section 524 or adjacent the downstream end 526 of the combustion chamber 228). The length 528 of the combustion chamber 228 can be measured between the upstream end 520 and the downstream end 526.

[0193] Further, the size (e.g., height 550 in the radial direction R) of the second fuel cell stack 232B is greater than the size (e.g., height 552 in the radial direction R) of the first fuel cell stack 232A. For example, the height 550 is 1.1 to 2 times the height 552. In certain embodiments, the greater height in the radial direction R can be achieved by stacking fuel cells end-to-end in the radial direction R or by simply using longer fuel cells.

[0194] The greater height can allow the second fuel cell stack 232B to generate more electrical power for a given number of fuel cells. Additionally or alternatively, the greater height can allow the second fuel cell stack 232B to provide output products 248B to the combustion chamber 228 near the downstream end 526 in a manner that better promotes more complete combustion and thus fewer emissions.

[0195] For example, the controller 240 controls the power converter 236 Figure 2 ) to increase or decrease the current (I) drawn from the second fuel cell stack 232B, and controls the valves to control the amount of fuel provided to the second fuel cell stack 232B and the amount, pressure, and temperature of air, in turn controlling aspects of the output products 248B provided at the downstream section 524 of the combustion chamber 228.

[0196] In at least certain example aspects, an increase in the current (I) drawn by the power converter 236 can result in more hydrogen being consumed in the second fuel cell stack 232B (e.g., converted to electricity) and less fuel being emitted from the second fuel cell stack 232B into the combustion chamber 228. Thus, the second fuel cell stack 232B can provide less combustible gas into the combustion chamber 228, which can act as a vaporizer to reduce nitrogen oxides (NO x ) emissions. The flow of less combustible gas can be referred to as a high purity flow. The high purity flow quenches the NO x reaction. The NO x decreases exponentially with an increase in water or steam injection or an increase in specific humidity.

[0197] Further, providing output products at the downstream section 524 (late lean) reduces the residence time of the output products and thus reduces NO x .

[0198] In other example aspects, for a desired total heat input of the integrated fuel cell and combustor assembly 200, less aircraft fuel can be provided to the combustor 206 through the combustor nozzle at the upstream end 520 of the combustion chamber. With this configuration, for a given air and fuel flow, less current can be drawn from the second fuel cell stack 232B, such that the output product 248B provided near the downstream end 526 contains a higher amount of combustible gas, such as H2, allowing for a lower peak temperature within the combustion chamber 228, and thus resulting in less NOx x formed.

[0199] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural

[0200] Further aspects are provided by the subject matter of the following clauses:

[0201] A propulsion system for an aircraft, the aircraft including an aircraft fuel supply, the propulsion system comprising: a turbomachine including, in serial flow order, a compressor section, a combustor, and a turbine section, the combustor defining a combustion chamber and an opening at an upstream end of the combustion chamber, the turbomachine defining an axial direction, the combustor being configured to receive a flow of aviation fuel from the aircraft fuel supply through the opening; and a fuel cell stack extending around the combustion chamber and configured to provide an output product to the combustion chamber to achieve at least one of a late lean injection and a desired combustor gas concentration profile, wherein the fuel cell stack is positioned along the axial direction (A) downstream of the combustion chamber.

[0202] The propulsion system according to one or more of these clauses, wherein the propulsion system defines a downstream distance in the axial direction between the opening of the combustor and an upstream end of the fuel cell stack, and wherein the downstream distance is at least 30% of a length of the combustion chamber in the axial direction.

[0203] The propulsion system according to one or more of these clauses, wherein the downstream distance is at least half of the length of the combustion chamber in the axial direction.

[0204] The propulsion system according to one or more of these clauses, wherein the downstream distance is greater than two-thirds of the length of the combustion chamber in the axial direction.

[0205] The propulsion system according to one or more of these clauses, wherein the downstream distance in the axial direction (A) is a distance between the opening and a next downstream flow of output products into the combustion chamber.

[0206] The propulsion system according to one or more of these clauses, wherein the fuel cell stack is a forward-most fuel cell stack.

[0207] The propulsion system according to one or more of these clauses, wherein the combustor includes an outer liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the outer liner.

[0208] The propulsion system according to one or more of these clauses, wherein the combustor includes an inner liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the inner liner.

[0209] The propulsion system according to one or more of these clauses, wherein the fuel cell stack is configured to achieve a desired combustor gas composition profile.

[0210] The propulsion system according to one or more of these clauses, wherein the combustor gas composition profile is along at least one of an axial direction and a circumferential direction of the combustor.

[0211] The propulsion system according to one or more of these clauses, wherein the combustor gas composition profile includes carbon monoxide, carbon dioxide, water vapor, unburned hydrocarbons, particulate matter, NOx, excess atmospheric oxygen, and nitrogen.

[0212] An integrated fuel cell and combustor assembly for a turbomachine, the turbomachine defining an axial direction, the integrated fuel cell and combustor assembly comprising: a combustor defining a combustion chamber and an opening at an upstream end of the combustion chamber, the combustor configured to receive a flow of aviation fuel through the opening when incorporated into the turbomachine; and a fuel cell stack extending around the combustion chamber and configured to provide output products to the combustion chamber, wherein the fuel cell stack is positioned in a downstream section of the combustion chamber along the axial direction.

[0213] The integrated fuel cell and combustor assembly of one or more of these clauses, wherein the integrated fuel cell and combustor assembly defines a downstream distance in the axial direction between the opening of the combustor and an upstream end of the fuel cell stack, and wherein the downstream distance is at least 30% of a length of the combustion chamber in the axial direction.

[0214] The integrated fuel cell and combustor assembly of one or more of these clauses, wherein the downstream distance is at least half of the length of the combustion chamber in the axial direction.

[0215] The integrated fuel cell and combustor assembly of one or more of these clauses, wherein the downstream distance in the axial direction is a distance between the opening and a next downstream flow of output products into the combustion chamber.

[0216] The integrated fuel cell and combustor assembly of one or more of these clauses, wherein the fuel cell stack is a forward-most fuel cell stack.

[0217] The integrated fuel cell and combustor assembly of one or more of these clauses, wherein the combustor includes an outer liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the outer liner.

[0218] The integrated fuel cell and combustor assembly of one or more of these clauses, wherein the combustor includes an inner liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the inner liner.

[0219] A method of operating a propulsion system including a turbine defining an axial direction and a fuel cell stack, the method comprising: providing a flow of aviation fuel to a combustion chamber of a combustor of the turbine through an opening defined at an upstream end of the combustion chamber to initiate primary combustion within the combustion chamber; and providing a flow of output products from the fuel cell stack to the combustion chamber at a downstream section of the combustion chamber to initiate secondary combustion within the combustion chamber at a location downstream of the primary combustion within the combustion chamber.

[0220] The method of one or more of these clauses, wherein the propulsion system defines a downstream distance in the axial direction between the opening and an upstream end of the fuel cell stack, and wherein the downstream distance is at least half of a length of the combustion chamber in the axial direction.

Claims

1. A propulsion system for an aircraft, the aircraft comprising an aircraft fuel supply, characterized in that, The propulsion system includes: a turbine including, in serial flow order, a compressor section, a combustor, and a turbine section, the combustor defining a combustion chamber and an opening at an upstream end of the combustion chamber, the turbine defining an axial direction, the combustor configured to receive a flow of aviation fuel from the aircraft fuel supply through the opening; and a fuel cell stack extending around the combustion chamber and configured to provide an output product to the combustion chamber to achieve at least one of a late lean injection and a desired combustor gas concentration profile, wherein the fuel cell stack is positioned in a downstream section of the combustion chamber along the axial direction (A); wherein fuel of the plurality of fuel cell stacks can be varied to distribute the output product or fuel to the combustor along the axial direction of the combustor; the late lean injection to inject a fuel / air mixture to a rear end of a primary combustion chamber defined by a liner, enabling fuel combustion to occur downstream of a primary combustor / primary combustion zone; the desired combustor gas concentration profile includes at least one of: providing the output product at a location downstream of the combustion chamber to reduce a residence time of the output product in the combustion chamber, thereby reducing emissions of the combustion chamber; determining a distribution of the output product such that a temperature along a length of the combustion chamber is within a low-emission temperature range; providing the output product at different locations along the length of the combustion chamber to move the temperature within a low-emission temperature range by increasing or decreasing the temperature, thereby reducing emissions; or, modifying a composition or distribution of the output product to provide more complete combustion of combustion gases generated within the combustion chamber and reduce emissions.

2. The propulsion system of claim 1, wherein, wherein the propulsion system defines a downstream distance in the axial direction between the opening of the combustor and an upstream end of the fuel cell stack, and wherein the downstream distance is at least 30% of a length of the combustion chamber in the axial direction.

3. The propulsion system of claim 2, wherein, wherein the downstream distance is at least one half of the length of the combustion chamber in the axial direction.

4. The propulsion system of claim 2, wherein, wherein the downstream distance is greater than two-thirds of the length of the combustion chamber in the axial direction.

5. The propulsion system of claim 2, wherein, wherein the downstream distance in the axial direction (A) is a distance between the opening and a next downstream flow of output product into the combustion chamber.

6. The propulsion system of claim 2, wherein, wherein the fuel cell stack is a forward-most fuel cell stack.

7. The propulsion system of claim 1, wherein, wherein the combustor includes an outer liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the outer liner.

8. The propulsion system of claim 1, wherein, wherein the combustor includes an inner liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the inner liner.

9. The propulsion system of claim 1, wherein, wherein the fuel cell stack is configured to achieve a desired combustor gas composition profile.

10. The propulsion system of claim 9, wherein, wherein the combustor gas composition profile is along at least one of an axial direction and a circumferential direction of the combustor.

11. The propulsion system of claim 9, wherein, wherein the combustor gas composition profile includes emissions indicators including carbon monoxide, carbon dioxide, water vapor, unburned hydrocarbons, particulate matter, NO x x, excess atmospheric oxygen, and nitrogen.

12. An integrated fuel cell and combustor assembly for a turbine, the turbine defining an axial direction, characterized by, The integrated fuel cell and combustor assembly includes: a combustor defining a combustion chamber and an opening at an upstream end of the combustion chamber, the combustor configured to receive a flow of aviation fuel through the opening when incorporated into the turbine; and a fuel cell stack extending around the combustion chamber and configured to provide an output product to the combustion chamber, wherein the fuel cell stack is positioned in a downstream section of the combustion chamber along the axial direction; wherein a fuel of a plurality of the fuel cell stacks can be varied to distribute the output product or fuel to the combustor along the axial direction of the combustor to achieve at least one of: injecting a fuel / air mixture to a rear end of a primary combustion chamber defined by a liner to enable fuel combustion to occur downstream of a primary combustor / primary combustion zone; providing the output product at a downstream location of the combustion chamber to reduce a residence time of the output product in the combustion chamber to reduce emissions of the combustion chamber; determining a distribution of the output product such that a temperature along a length of the combustion chamber is within a low emission temperature range; providing the output product at different locations along the length of the combustion chamber to move a temperature within a low emission temperature range by increasing or decreasing the temperature to reduce emissions; or, modifying a composition or distribution of the output product to provide more complete combustion of combustion gases generated within the combustion chamber and reduce emissions.

13. The integrated fuel cell and combustor assembly of claim 12, wherein, wherein the integrated fuel cell and combustor assembly defines a downstream distance in the axial direction between the opening of the combustor and an upstream end of the fuel cell stack, and wherein the downstream distance is at least 30% of a length of the combustion chamber in the axial direction.

14. The integrated fuel cell and combustor assembly of claim 13, wherein, wherein the downstream distance is at least half of the length of the combustion chamber in the axial direction.

15. The integrated fuel cell and combustor assembly of claim 13, wherein, wherein the downstream distance in the axial direction is a distance between the opening and a next downstream flow of output product into the combustion chamber.

16. The integrated fuel cell and combustor assembly of claim 13, wherein, wherein the fuel cell stack is a forward-most fuel cell stack.

17. The integrated fuel cell and combustor assembly of claim 12, wherein, wherein the combustor includes an outer liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the outer liner.

18. The integrated fuel cell and combustor assembly of claim 12, wherein, wherein the combustor includes an inner liner at least partially defining the combustion chamber, wherein the fuel cell stack extends around or is integrated into the inner liner.

19. A method of operating a propulsion system, the propulsion system comprising a turbine and a fuel cell stack, the turbine defining an axial direction, characterised by, the method comprising: providing a flow of aviation fuel to a combustion chamber of a combustor of a turbine through an opening defined at an upstream end of the combustion chamber to initiate initial combustion within the combustion chamber; and providing a flow of an output product from the fuel cell stack to the combustion chamber at a downstream section of the combustion chamber to initiate secondary combustion within the combustion chamber at a downstream location of the initial combustion within the combustion chamber; wherein a fuel of a plurality of the fuel cell stacks can be varied to distribute the output product or fuel to the combustor along the axial direction of the combustor to achieve at least one of: injecting a fuel / air mixture to a rear end of a primary combustion chamber defined by a liner to enable fuel combustion to occur downstream of a primary combustor / primary combustion zone; providing the output product at a location downstream of the combustion chamber to reduce the residence time of the output product in the combustion chamber, thereby reducing emissions from the combustion chamber; determining a profile of the output product such that the temperature along the length of the combustion chamber is within a low emissions temperature range; providing the output product at different locations along the length of the combustion chamber to move the temperature into a low emissions temperature range by increasing or decreasing the temperature, thereby reducing emissions; or, modifying the composition or profile of the output product to provide more complete combustion of combustion gases generated within the combustion chamber and reduce emissions.

20. The method of claim 19, wherein, wherein the propulsion system defines a downstream distance in the axial direction between the opening and the upstream end of the fuel cell stack, and wherein the downstream distance is at least half of the length of the combustion chamber in the axial direction.

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