An energy storage and retrieval system is disclosed. The system includes a heat generating layer for generating thermal energy based on combusting a combustible substance and a thermal energy storage layer located to receive thermal energy from the heat generating layer. The thermal energy storage layer includes a thermal energy storage material to store thermal energy. The system also includes a thermal energy retrieval layer thermally connectable to the thermal energy storage material and configurable to retrieve thermal energy from the thermal energy storage layer.

An energy storage and retrieval system is disclosed. The system includes a heat generating layer for generating thermal energy based on combusting a combustible substance and a thermal energy storage layer located to receive thermal energy from the heat generating layer. The thermal energy storage layer includes a thermal energy storage material to store thermal energy. The system also includes a thermal energy retrieval layer thermally connectable to the thermal energy storage material and configurable to retrieve thermal energy from the thermal energy storage layer.

An embodiment of a torch ignitor system for combustor of a gas turbine engine includes a torch ignitor, the torch ignitor having a combustion chamber oriented about an axis, the combustion chamber having axially upstream and downstream ends defining a flow direction through the combustion chamber, along the axis. The torch ignitor system also includes a cap defining the axially upstream end of the combustion chamber and oriented about the axis, wherein the cap is configured to receive a fuel injector and at least one glow plug, a tip at a downstream end of the combustion chamber, and a passage for pressurized oxygen containing gas passing through the cap from an exterior of the combustion chamber and in fluid communication with the combustion chamber. An embodiment of a method for starting a gas turbine engine is also disclosed.

An embodiment of a torch ignitor system for combustor of a gas turbine engine includes a torch ignitor, the torch ignitor having a combustion chamber oriented about an axis, the combustion chamber having axially upstream and downstream ends defining a flow direction through the combustion chamber, along the axis. The torch ignitor system also includes a cap defining the axially upstream end of the combustion chamber and oriented about the axis, wherein the cap is configured to receive a fuel injector and at least one glow plug, a tip at a downstream end of the combustion chamber, and a passage for pressurized oxygen containing gas passing through the cap from an exterior of the combustion chamber and in fluid communication with the combustion chamber. An embodiment of a method for starting a gas turbine engine is also disclosed.

An engine system is provided for an aircraft having an engine and an engine controller. The engine system includes: an electric machine configured to be in electrical communication with the engine controller for powering the engine controller; and a fuel oxygen reduction unit defining a liquid fuel flowpath and a stripping gas flowpath and configured to transfer an oxygen content of a fuel flow through the liquid fuel flowpath to a stripping gas flow through the stripping gas flowpath, the fuel oxygen reduction unit also in electrical communication with the electric machine such that the electric machine powers at least in part the fuel oxygen reduction unit.

A fuel delivery system for a gas turbine engine including a fuel oxygen reduction unit is provided. The fuel oxygen reduction unit defines a liquid fuel flowpath and a stripping gas flowpath and is configured to transfer an oxygen content of a fuel flow through the liquid fuel flowpath to a stripping gas flow through the stripping gas flowpath. The fuel oxygen reduction unit includes an impeller in airflow communication with the stripping gas flowpath for circulating the stripping gas flow through the stripping gas flowpath; and a turbine coupled to the impeller.

A fuel delivery system for a gas turbine engine including a fuel oxygen reduction unit is provided. The fuel oxygen reduction unit defines a liquid fuel flowpath and a stripping gas flowpath and is configured to transfer an oxygen content of a fuel flow through the liquid fuel flowpath to a stripping gas flow through the stripping gas flowpath. The fuel oxygen reduction unit includes an impeller in airflow communication with the stripping gas flowpath for circulating the stripping gas flow through the stripping gas flowpath; and a turbine coupled to the impeller.

A fluid flow system includes a main valve having a spool, a first chamber, and a second chamber. A pressure difference between the first chamber and the second chamber is configured to move the spool to control fluid flow. An electromechanical meter interface device (EMID) is in fluid communication with at least one of the first and second chambers of the main valve. The EMID is configured to meter fluid from a first source and a second source to the at least one of the first chamber and the second chamber. The first source has a different pressure from the second source. A fixed orifice is arranged between the main valve and the EMID. A fuel system for a gas turbine engine is also disclosed.

A fluid flow system includes a main valve having a spool, a first chamber, and a second chamber. A pressure difference between the first chamber and the second chamber is configured to move the spool to control fluid flow. An electromechanical meter interface device (EMID) is in fluid communication with at least one of the first and second chambers of the main valve. The EMID is configured to meter fluid from a first source and a second source to the at least one of the first chamber and the second chamber. The first source has a different pressure from the second source. A fixed orifice is arranged between the main valve and the EMID. A fuel system for a gas turbine engine is also disclosed.

A metal catalytic converter system employs an engine having an exhaust duct. A multistage metal catalytic converter is mounted in the exhaust duct. A compressor stage is mounted in the exhaust duct, the compressor stage configured to reduce exhaust backpressure created by the converter.