Abstract: A propulsion system is provided including: a gas turbine engine including a combustion section having a combustor; and a modular fuel cell assembly. The modular fuel cell assembly includes: a first fuel cell string comprising a first processing unit and a first fuel cell stack, the first fuel cell stack comprising a first fuel cell defining an outlet configured to provide output products from the first fuel cell to the combustor; and a second fuel cell string comprising a second processing unit and a second fuel cell stack, the second fuel cell stack comprising a second fuel cell defining an outlet configured to provide output products from the second fuel cell to the combustor.

Abstract: An anti-stall system for an aircraft may be provided, where the aircraft includes a propulsion system including a fuel cell assembly and a combustion engine, the combustion engine including a compressor section having a compressor. The anti-stall system may include at least one sensor configured to sense data indicative of at least one operating parameter indicative of a compressor stall condition of the compressor; and a controller including a processor and a memory storing instructions that when executed by the processor cause the controller to determine that the at least one operating parameter has achieved a compressor stall condition threshold and execute an anti-stall action responsive to determining that the at least one operating parameter has achieved the compression stall condition threshold. The anti-stall action may be configured to adjust at least one fuel cell parameter.

Abstract: A method is provided for operating a propulsion system having a gas turbine engine and a fuel cell assembly. The fuel cell assembly includes a fuel cell. The method includes: receiving gas composition data of output products from the fuel cell; and controlling operation of the fuel cell assembly, the gas turbine engine, or both in response to the received gas composition data of the output products from the fuel cell.

Abstract: A propulsion system is provided including: a propulsor; a turbomachine operable to drive the propulsor to generate thrust during operation; a fuel cell assembly configured to add power to the propulsor, the turbomachine, or both; and a multi-gas sensor operable with the turbomachine, the fuel cell assembly, or both for sensing gas composition data of a fluid flow in or to the turbomachine, the fuel cell assembly, or both, the gas composition data comprising data indicative of at least two gases and their concentrations.

Abstract: A gas turbine engine and combustor assembly are provided, the combustor assembly including a first liner and a second liner together defining at least in part a combustion chamber, wherein the first liner and the second liner are separated by a gap along the longitudinal direction, and wherein the first liner is forward of the second liner relative to a flow of fluid through the combustion chamber along the longitudinal direction, and wherein the gap is extended along the circumferential direction.

Abstract: Systems and methods including a reformer stack extended around a combustion chamber. The reformer stack is configured to provide output products to 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 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 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 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: Systems and methods including a plurality of reformer stacks extended around the combustion chamber. The reformer stacks are distributed along a length of the combustion chamber in the axial direction and configured to provide output products to the combustion chamber.

Abstract: Systems and methods of aircraft thrust management are provided. For example, a propulsion system for an aircraft comprises a fuel cell assembly comprising a fuel cell, a turbomachine, and a controller comprising memory and one or more processors. The memory stores instructions that, when executed by the one or more processors, cause the propulsion system to perform operations including receiving data indicative of a propulsion system thrust discrepancy and modifying an output of the fuel cell in response to receiving data indicative of the propulsion system thrust discrepancy. Modifying the fuel cell output may include modifying output products, an electrical power output, or both of the fuel cell to balance the thrust provided by the propulsion system.

Abstract: Systems and methods include a plurality of fuel cell stacks extended around a combustion chamber. The plurality of fuel cell stacks are distributed along a length of the combustion chamber in the axial direction. The fuel cell stacks are configured to provide output products to the combustion chamber to achieve at least one of late lean injection and a desired combustor gas concentration distribution.

Abstract: Systems and methods include a fuel cell stack extended around a combustion chamber that is configured to provide output products to the combustion chamber to achieve at least one of late lean injection and a desired combustor gas concentration distribution. The fuel cell stack is positioned at a downstream section of the combustion chamber along an axial direction.

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 includes a fuel cell assembly including a fuel cell stack and defining a fuel cell assembly operating parameter, a fuel source, and a turbomachine. The turbomachine includes a compressor section, a combustor, and a turbine section arranged in serial flow order. The combustor is configured to receive a flow of fuel from the fuel source and further configured to receive output products from the fuel cell stack. A controller is configured to perform operations including receiving data indicative of system operation conditions, determining a set of fuel cell operating conditions to move the system emission output into or maintain the system emission output within an emissions range, and controlling the fuel cell assembly operating parameter according to the determined set of fuel cell operating conditions.

Abstract: Systems and methods configured to receive a set of real-time flight conditions and a user-selected objective function. The user-selected objective function is one of a plurality of objective functions. The systems and methods determine, with an emissions tuning model, one of a plurality of sets of fuel cell operating conditions based on the set of real-time flight conditions and the user-selected objective function. The systems and methods are configured to control a fuel cell assembly operating parameter according to the determined one of the plurality of sets of fuel cell operating conditions.

Abstract: Systems and methods including a reformer stack extended around a combustion chamber. The reformer stack is configured to provide output products to the combustion chamber.

Abstract: A propulsion system including: a fuel cell assembly comprising a fuel cell, the fuel cell defining an outlet positioned to remove output products from the fuel cell and a fuel cell assembly operating condition; a combustion section that includes a combustor configured to receive a flow of aviation fuel from the 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: determining data indicative of at least one of an enthalpy or a composition of the output products from the fuel cell; and modifying the flow of aviation fuel from the aircraft fuel supply to the combustor based on the at least one of the enthalpy or the composition of the output products.

Abstract: A propulsion system for an aircraft includes a fuel cell assembly, the fuel cell assembly including a fuel cell, and a turbomachine, the turbomachine including a compressor section, a combustor, and a turbine section arranged in serial flow order. The combustor is configured to receive a flow of fuel and further configured to receive output products from the fuel cell. A controller is configured to receive data indicative of an engine constraint of the turbomachine, determine that the engine constraint has achieved a fuel cell trim threshold; and perform a fuel cell corrective action with the fuel cell assembly in response to determining that the engine constraint has achieved the fuel cell trim threshold.