There are described methods and systems for operating an aircraft having two or more engines. One method comprises operating the two or more engines of the aircraft in an asymmetric operating regime, wherein a first of the engines is in an active mode to provide motive power to the aircraft and a second of the engines is in a standby mode to provide substantially no motive power to the aircraft; governing the first engine in the active mode using a first governing logic; and governing the second engine in the standby mode using a second governing logic, the second governing logic based on a target compressor speed and variable geometry mechanism (VGM) settings that are adjusted using trim values dependent on at least one parameter of the second engine in the standby mode.

There are described methods and systems for operating an aircraft having two or more engines. One method comprises operating the two or more engines of the aircraft in an asymmetric operating regime, wherein a first of the engines is in an active mode to provide motive power to the aircraft and a second of the engines is in a standby mode to provide substantially no motive power to the aircraft; governing the first engine in the active mode using a first governing logic; and governing the second engine in the standby mode using a second governing logic, the second governing logic based on a target compressor speed and variable geometry mechanism (VGM) settings that are adjusted using trim values dependent on at least one parameter of the second engine in the standby mode.

An anti-icing system of a nacelle inlet of an engine of an aircraft includes first and second direct acting valves and first and second control valve assemblies fluidly connected to the nacelle inlet. The first direct acting valve includes a first inlet, outlet, valve chamber, and piston. The first piston is positioned in the first direct acting valve. The first control valve assembly is fluidly connected to the first valve. The second direct acting valve includes a second inlet, outlet, valve chamber, and piston. The second piston is positioned in the second direct acting valve. The second direct acting valve is fluidly connected to the first direct acting valve in a series configuration. The second control valve assembly is fluidly connected to the second valve chamber.

An anti-icing system of a nacelle inlet of an engine of an aircraft includes first and second direct acting valves and first and second control valve assemblies fluidly connected to the nacelle inlet. The first direct acting valve includes a first inlet, outlet, valve chamber, and piston. The first piston is positioned in the first direct acting valve. The first control valve assembly is fluidly connected to the first valve. The second direct acting valve includes a second inlet, outlet, valve chamber, and piston. The second piston is positioned in the second direct acting valve. The second direct acting valve is fluidly connected to the first direct acting valve in a series configuration. The second control valve assembly is fluidly connected to the second valve chamber.

A system includes a generator using a fluid mixture obtained via a generator inlet, a compressor having a compressor inlet that is connected to a generator outlet by a first set of conduits, a second set of conduits connected to the compressor outlet and the generator inlet, and a sensor in communication with the second set of conduits, where a portion of the fluid mixture includes gas from a hydrocarbon well, and where exhaust fluid of the generator is provided to the compressor. A process includes obtaining a target fluid property and a fluid measurement using the sensor and modifying a parameter of a fluid control device to modify a first flow rate of the flow of the exhaust fluid through the second set of conduits relative to a second flow rate of the flow of the gas provided by the hydrocarbon well through the first set of conduits.

A system includes a generator using a fluid mixture obtained via a generator inlet, a compressor having a compressor inlet that is connected to a generator outlet by a first set of conduits, a second set of conduits connected to the compressor outlet and the generator inlet, and a sensor in communication with the second set of conduits, where a portion of the fluid mixture includes gas from a hydrocarbon well, and where exhaust fluid of the generator is provided to the compressor. A process includes obtaining a target fluid property and a fluid measurement using the sensor and modifying a parameter of a fluid control device to modify a first flow rate of the flow of the exhaust fluid through the second set of conduits relative to a second flow rate of the flow of the gas provided by the hydrocarbon well through the first set of conduits.

A gas turbine engine comprising: a duct extending about an axis, the duct including an outer-duct wall having an interior-duct surface circumscribing an interior of the duct and an exterior-duct surface radially outward of the interior-duct surface relative to the axis, the outer-duct wall defining an offtake opening extending from the interior-duct surface to the exterior-duct surface, the offtake opening in fluid communication between an offtake location inside the duct and outside the duct, and a bleed air offtake assembly including: an air line in fluid communication with inside the duct via the offtake opening, the air line having a first-line end defining a line inlet proximate to the outer-duct wall and a second-line end spaced from the first-line end; a valve located outside the duct and fluidly connected to the air line via the second-line end, and a conduit having a conduit inlet in fluid communication with inside the air line at a resonance location between the first-line end and the second-line end upstream of the valve, and a conduit outlet in fluid communication with inside the duct at a relief location spaced from the offtake location.

Shape memory alloy (SMA) actuators and thermal management systems including the same. An SMA actuator includes an SMA lifting tube and a process fluid conduit configured to convey a process fluid through the SMA lifting tube. The SMA actuator assumes a conformation that is based on the temperature of the process fluid. The SMA lifting tube includes a first end and a second end configured to translate relative to the first end at least partially along a lateral direction. A thermal management system is configured to regulate a temperature of a process fluid. The thermal management system includes a heat exchanger that at least partially defines a heat transfer region, a process fluid conduit configured to convey the process fluid through the heat transfer region, and an actuator assembly including the SMA actuator. The actuator assembly is configured to selectively position the heat exchanger within a thermal management fluid flow.

Shape memory alloy (SMA) actuators and thermal management systems including the same. An SMA actuator includes an SMA lifting tube and a process fluid conduit configured to convey a process fluid through the SMA lifting tube. The SMA actuator assumes a conformation that is based on the temperature of the process fluid. The SMA lifting tube includes a first end and a second end configured to translate relative to the first end at least partially along a lateral direction. A thermal management system is configured to regulate a temperature of a process fluid. The thermal management system includes a heat exchanger that at least partially defines a heat transfer region, a process fluid conduit configured to convey the process fluid through the heat transfer region, and an actuator assembly including the SMA actuator. The actuator assembly is configured to selectively position the heat exchanger within a thermal management fluid flow.

A system includes an air manifold, a fuel manifold, and a plurality of fuel injectors. At least one of the fuel injectors includes a heat exchanger portion for supplying compressed, cooled air form the heat exchanger portion to the air manifold. An air valve is operatively connected to an outlet of the air manifold for controlling release of air from the air manifold. A controller is operatively connected to the air valve, wherein the controller includes machine readable instructions configured to control the air valve to regulate flow of air through the air valve based on fuel temperatures in the fuel channel. The machine readable instructions can be configured to cause the controller to flow air through the air valve in a heat exchange mode if a fuel temperature in the fuel injectors is below a predetermined fuel temperature.