Abstract: A combustion section includes a casing that defines a diffusion chamber. The combustion section further includes a combustion liner that is disposed within the diffusion chamber and that defines a combustion chamber. The combustion liner is spaced apart from the casing such that a passageway is defined between the combustion liner and the casing. The combustion section further includes a fuel cell assembly that is disposed in the passageway. The fuel cell assembly includes a fuel cell stack having a plurality of fuel cells. The plurality of fuel cells extend from an inlet end in fluid communication with the diffusion chamber to an outlet end extending through the combustion liner and in fluid communication with the combustion chamber.

Abstract: A combustion section defines an axial direction, a radial direction, and a circumferential direction. The combustion section includes a casing that defines a diffusion chamber. A combustion liner is disposed within the diffusion chamber and defines a combustion chamber the combustion liner is spaced apart from the casing such that a passageway is defined between the combustion liner and the casing. A fuel cell assembly is disposed in the passageway. The fuel cell assembly includes a fuel cell stack that has a plurality of fuel cells each extending between an inlet end and an outlet end. The inlet end receives a flow of air and fuel and the outlet end provides output products to the combustion chamber. The fuel cell assembly further includes an electrical circuit that is electrically coupled to the plurality of fuel cells and that extends through the casing.

Abstract: A combustion section defines an axial direction, a radial direction, and a circumferential direction. The combustion section includes a casing that defines a diffusion chamber. A combustion liner is disposed within the diffusion chamber and defines a combustion chamber. The combustion liner is spaced apart from the casing such that a passageway is defined between the combustion liner and the casing. A fuel cell assembly is disposed in the passageway. The fuel cell assembly includes a fuel cell that extends between an inlet end and an outlet end. The inlet end receives a flow of air and fuel and the outlet end provides output products to the combustion chamber. The fuel cell extends at an angle between the inlet end and the outlet end relative to a radial projection line.

Abstract: A combustion section defines an axial direction, a radial direction, and a circumferential direction. The combustion section includes a casing that defines a diffusion chamber. A combustion liner is disposed within the diffusion chamber and defines a combustion chamber. The combustion liner is spaced apart from the casing such that a passageway is defined between the combustion liner and the casing. A fuel cell assembly is disposed in the passageway. The fuel cell assembly includes a fuel cell stack having a plurality of fuel cells each extending between an inlet end and an outlet end. Each fuel cell of the plurality of fuel cells includes an air channel and a fuel channel each fluidly coupled to the combustion chamber.

Abstract: A fuel cell unit that includes a support structure having a plurality of flow channels and an active layer membrane coupled with the support structure, the active layer membrane comprising at least one electrode layer. Each flow channel of the plurality of flow channels is configured to direct one of air and fuel across at least one electrode layer of an active layer membrane to create electric current. Each flow channel of the plurality of flow channels includes at least one enhancement feature that is configured to disrupt a formation of a boundary layer near a surface of the active layer membrane where reactions occur. The plurality of flow channels can be positioned in a zig-zag configuration to allow for an increase in power density of the fuel cell unit.

Abstract: A combustion section defines an axial direction, a radial direction, and a circumferential direction. The combustion section includes a casing that defines a diffusion chamber. A combustion liner is disposed within the diffusion chamber and defines a combustion chamber. The combustion liner is spaced apart from the casing such that a passageway is defined between the combustion liner and the casing. A fuel cell assembly is disposed in the passageway. The fuel cell assembly includes a fuel cell stack that has a plurality of fuel cells each extending between an inlet end and an outlet end. The inlet end receives a flow of air and fuel and the outlet end provides output products to the combustion chamber. The outlet end of the plurality of fuel cells extends through the combustion liner and partially defines the combustion chamber.

Abstract: A method for operating a propulsion system for an aircraft, the propulsion system including a gas turbine engine and a fuel cell assembly, the fuel cell assembly including a fuel cell stack having a solid oxide fuel cell defining an outlet positioned to remove output products from the solid oxide fuel cell during operation, the method including: operating the fuel cell assembly to provide output products to a combustor of a combustion section of the gas turbine engine; and operating the fuel cell assembly, the gas turbine engine, or both such that a pressure within an anode of the solid oxide fuel cell is less than a pressure within a cathode of the solid oxide fuel cell, is less than a pressure within a combustion chamber of the gas turbine engine, or both while operating the gas turbine engine.

Abstract: A propulsion system for an aircraft, the aircraft including an aircraft fuel supply, the propulsion system including: a turbomachine including a compressor section, a combustion section, and a turbine section arranged in serial flow order, the combustion section configured to receive a flow of aviation fuel from the aircraft fuel supply; and a fuel cell assembly including a fuel cell stack having a solid oxide fuel cell, the solid oxide fuel cell defining an outlet positioned to remove output products from the solid oxide fuel cell and provide the output products to the combustion section, the solid oxide fuel cell including a cathode; an electrolyte layer; and an anode positioned opposite the electrolyte layer from the cathode, the anode including a cermet, the cermet including less than 25% by volume nickel.

Abstract: A method for operating a fuel cell assembly, the fuel cell assembly including a fuel cell stack having a solid oxide fuel cell, the solid oxide fuel cell having an anode, a cathode, and an electrolyte, the method including: determining a temperature setpoint for the fuel cell stack, for output products of the fuel cell stack, or both; and controlling a volume of oxidant provided to the anode in response to the determined temperature setpoint to control a temperature of the fuel cell stack, a temperature of the output products of the fuel cell stack, or both.

Abstract: A method for operating a propulsion system for an aircraft, the propulsion system including a gas turbine engine and a fuel cell assembly, the fuel cell assembly including a fuel cell stack having a solid oxide fuel cell defining an outlet positioned to remove output products from the solid oxide fuel cell during operation, the method including: operating the fuel cell assembly to provide output products to a combustor of a combustion section of the gas turbine engine; and operating the fuel cell assembly, the gas turbine engine, or both such that a pressure within an anode of the solid oxide fuel cell is less than a pressure within a cathode of the solid oxide fuel cell, is less than a pressure within a combustion chamber of the gas turbine engine, or both while operating the gas turbine engine.

Abstract: A method for operating a propulsion system for an aircraft, the propulsion system including a gas turbine engine and a fuel cell assembly, the fuel cell assembly comprising a fuel cell stack having a fuel cell defining an outlet positioned to remove output products from the fuel cell during operation, the method including: executing a startup sequence for the gas turbine engine, wherein executing the startup sequence comprises initiating the startup sequence for the gas turbine engine; executing a startup sequence for the fuel cell assembly concurrently with, or subsequent to, initiating the startup sequence for the gas turbine engine; and operating the fuel cell assembly to provide output products to a combustion section of the gas turbine engine.

Abstract: A method for operating a propulsion system for an aircraft, the propulsion system including a gas turbine engine and a fuel cell assembly, the fuel cell assembly including a fuel cell stack having a fuel cell defining an outlet positioned to remove output products from the fuel cell during operation, the method including: executing a startup sequence for the fuel cell assembly, wherein executing the startup sequence for the fuel cell assembly includes initiating the startup sequence for the fuel cell assembly; executing a startup sequence for the gas turbine engine, wherein executing the startup sequence for the gas turbine engine comprises initiating the startup sequence for the gas turbine engine subsequent to initiating the startup sequence for the fuel cell assembly; and operating the fuel cell assembly to provide output products to a combustion section of the gas turbine engine.

Abstract: A safety management system for an aircraft, or a propulsion system thereof including a fuel cell assembly and a combustion engine, may include various sensors and controllers configured to execute a safety action. At least one sensor is configured to detect at least one operating parameter of the propulsion system, and a controller is configured to determine that the at least one operating parameter has achieved a safety threshold and to execute a safety action when the at least one operating parameter has achieved the safety threshold. The safety action is configured to control operation of the fuel cell assembly and to control operation of the combustion engine.

Abstract: A gas turbine engine including a catalytic reactor and a combustor. The catalytic reactor is configured (i) to receive hydrogen fuel, (ii) to receive air containing oxygen, (iii) to catalytically react at least a portion of the oxygen in the air with at least a portion of the hydrogen in the hydrogen fuel to produce water, and (iv) to output diluent comprising the catalytically produced water. The combustor includes (a) a combustion chamber and (b) at least one nozzle that is fluidly coupled to the catalytic reactor to receive the diluent output by the catalytic reactor and configured to inject the diluent into the combustion chamber.

Abstract: A propulsion system including: a fuel cell assembly having a fuel cell defining an outlet positioned to remove output products from the fuel cell and a fuel cell assembly operating condition; a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the combustion section configured to receive a flow of aviation fuel from an aircraft fuel supply and further configured to receive the output products from the fuel cell; and a controller comprising memory and one or more processors, the memory storing instructions that when executed by the one or more processors cause the propulsion system to perform operations including receiving data indicative of a mid-flight flameout within the combustion section; modifying the fuel cell assembly operating condition in response to receiving data indicative of the mid-flight flameout within the combustion section; and initiating a relight of the combustion section.

Abstract: An integrated fuel cell and combustor assembly includes a combustor that is fluidly coupled with at least one upstream compressor that generates compressed air. A fuel cell stack having a cathode and an anode is fluidly coupled to the combustor. The fuel cell stack is configured to receive intake fuel and a portion of the compressed air as intake air, to generate a fuel cell power output using the intake fuel and the intake air, and to direct a fuel and air exhaust from the fuel cell stack into the combustor. A self-reliant air supply system is fluidly coupled with the at least one upstream compressor and the fuel cell stack, and is configured to supply the intake air to the fuel cell stack. A fault-tolerant controller is configured to detect a transient event within the combustor and to control the self-reliant air supply system during the transient event.

Abstract: An engine assembly includes a combustor, a fuel cell stack fluidly connected to the combustor, the fuel cell stack being configured (i) to generate power using fuel and air directed into the fuel cell stack and (ii) to direct fuel and air exhaust from the fuel cell stack into the combustor, a compressor fluidly connected upstream of (i) the combustor and (ii) the fuel cell stack, the compressor being configured to generate compressed air to direct into the fuel cell stack, a turbine disposed downstream from the combustor, the turbine having a turbine inlet temperature, and a controller that is configured to control a power allocation between the fuel cell stack and the turbine based upon the turbine inlet temperature of the turbine. The combustor is configured to combust the fuel and air exhaust from the fuel cell stack into one or more gaseous combustion products that power the turbine.

Abstract: An engine assembly includes a combustor, a fuel cell stack integrated with the combustor, the fuel cell stack configured (i) to direct fuel and air exhaust from the fuel cell stack into the combustor and (ii) to generate electrical energy, a catalytic partial oxidation convertor that is fluidly connected to the fuel cell stack, the catalytic partial oxidation convertor being configured to optimize a hydrogen content of a fuel stream to be directed into the fuel cell stack, and one or more subsystems electrically connected with the fuel cell stack, the one or more subsystems being configured to receive the electrical energy generated by the fuel cell stack. The combustor is configured to combust the fuel and air exhaust from the fuel cell stack into one or more gaseous combustion products that drive a downstream turbine.

Abstract: An engine assembly includes a combustor, a fuel cell stack integrated with the combustor, and a pre-burner system fluidly connected to the fuel cell stack. The fuel cell stack is configured to direct fuel and air exhaust from the fuel cell stack into the combustor. The pre-burner system is configured to control a temperature of an air flow directed into the fuel cell stack. The combustor is configured to combust the fuel and air exhaust from the fuel cell stack into one or more gaseous combustion products that drive a downstream turbine. The engine assembly can further include a catalytic partial oxidation convertor that is fluidly connected to the fuel cell stack. The catalytic partial oxidation convertor is configured to develop a hydrogen rich fuel stream to be directed into the fuel cell stack.

Abstract: A fuel cell unit that includes a support structure having a plurality of flow channels and an active layer membrane coupled with the support structure, the active layer membrane comprising at least one electrode layer. Each flow channel of the plurality of flow channels is configured to direct one of air and fuel across at least one electrode layer of an active layer membrane to create electric current. Each flow channel of the plurality of flow channels includes at least one enhancement feature that is configured to disrupt a formation of a boundary layer near a surface of the active layer membrane where reactions occur. The plurality of flow channels can be positioned in a zig-zag configuration to allow for an increase in power density of the fuel cell unit.