Abstract: An engine system includes a gas turbine engine with a first compressor, a first combustor, and first turbine. The engine system also includes a secondary power unit with a second compressor, a second combustor, a second turbine, a third compressor coupled to the second compressor, and an electric motor-generator, where the secondary power unit is coupled to the gas turbine engine and includes a heat exchanger. A controller is operable to determine an operating mode of the engine system, select an input energy source and an output type of the secondary power unit based on the operating mode, control the secondary power unit based on the input energy source and the output type as selected, detect a change in the operating mode of the engine system, and modify the input energy source and/or the output type of the secondary power unit based on the change in the operating mode.

Abstract: A heat exchanger can comprise: a housing; a heat transfer region disposed within the housing; and an inlet manifold or an inlet conduit defined at least partially by an interior surface extending axially from a first end of the heat exchanger to an inlet defined by the heat transfer region, the inlet manifold or the inlet conduit comprising a dimple configuration disposed in the interior surface. The heat exchanger can further comprise an outlet manifold or an outlet conduit including a dimple configuration disposed on an interior surface of the outlet manifold or outlet conduit.

Abstract: An engine system is provided that includes a compressor section, a combustor section, a turbine section, a flowpath and a flow regulator. The combustor section includes a combustion chamber. The flowpath extends sequentially through the compressor section, the combustor section and the turbine section. The flow regulator is configured to open the flowpath between the compressor section and the combustion chamber during a first mode of operation. The flow regulator is configured to at least substantially close the flowpath between the compressor section and the combustion chamber during a second mode of operation.

Abstract: An engine system includes a gas turbine engine with a first compressor, a first combustor, and first turbine. The engine system also includes a secondary power unit with a second compressor, a second combustor, a second turbine, a third compressor coupled to the second compressor, and an electric motor-generator, where the secondary power unit is coupled to the gas turbine engine and includes a heat exchanger. A controller is operable to determine an operating mode of the engine system, select an input energy source and an output type of the secondary power unit based on the operating mode, control the secondary power unit based on the input energy source and the output type as selected, detect a change in the operating mode of the engine system, and modify the input energy source and/or the output type of the secondary power unit based on the change in the operating mode.

Abstract: An engine system includes a gas turbine engine with a first compressor, a first combustor, and a first turbine. The engine system also includes a secondary power unit with a second compressor, a second combustor, a second turbine, a third compressor coupled to the second compressor, and an electric motor-generator, where the secondary power unit is coupled to the gas turbine engine. A controller is operable to determine an operating mode of the engine system, select an input energy source and an output type of the secondary power unit based on the operating mode, control the secondary power unit based on the input energy source and the output type as selected, detect a change in the operating mode of the engine system, and modify the input energy source and/or the output type of the secondary power unit based on the change in the operating mode.

Abstract: An engine system is provided that includes a compressor section, a combustor section, a turbine section, a flowpath and a flow regulator. The combustor section includes a combustion chamber. The flowpath extends sequentially through the compressor section, the combustor section and the turbine section. The flow regulator is configured to open the flowpath between the compressor section and the combustion chamber during a first mode of operation. The flow regulator is configured to at least substantially close the flowpath between the compressor section and the combustion chamber during a second mode of operation.

Abstract: An engine system includes a gas turbine engine with a first compressor, a first combustor, and a first turbine. The engine system also includes a secondary power unit with a second compressor, a second combustor, a second turbine, a third compressor coupled to the second compressor, and an electric motor-generator, where the secondary power unit is coupled to the gas turbine engine. A controller is operable to determine an operating mode of the engine system, select an input energy source and an output type of the secondary power unit based on the operating mode, control the secondary power unit based on the input energy source and the output type as selected, detect a change in the operating mode of the engine system, and modify the input energy source and/or the output type of the secondary power unit based on the change in the operating mode.

Abstract: A fluid system may comprise a fluid passage comprising a passage inlet and a passage outlet, through which fluid may flow by entering the passage inlet as an inlet flow and exiting the passage outlet as an outlet flow; a bypass valve comprising a bypass inlet and a bypass outlet, the bypass inlet being in fluid communication with the passage inlet, wherein the bypass valve further comprises a piston coupled to a spring; and a position sensor coupled to the bypass valve and configured to detect a position of the piston in the bypass valve. The spring may retain the piston in a rest position, and the spring and the piston may be configured to block the fluid from passing through the bypass outlet in response to the inlet flow exerting a pressure below a bypass pressure threshold.

Abstract: A fluid system may comprise a fluid passage comprising a passage inlet and a passage outlet, through which fluid may flow by entering the passage inlet as an inlet flow and exiting the passage outlet as an outlet flow; a bypass valve comprising a bypass inlet and a bypass outlet, the bypass inlet being in fluid communication with the passage inlet, wherein the bypass valve further comprises a piston coupled to a spring; and a position sensor coupled to the bypass valve and configured to detect a position of the piston in the bypass valve. The spring may retain the piston in a rest position, and the spring and the piston may be configured to block the fluid from passing through the bypass outlet in response to the inlet flow exerting a pressure below a bypass pressure threshold.