Methods and systems of operating a gas turbine engine in a low-power condition are provided. In one embodiment, the method includes supplying fuel to a combustor by supplying fuel to a first fuel manifold and a second fuel manifold of the gas turbine engine. The method also includes, while supplying fuel to the combustor by supplying fuel to the first fuel manifold: stopping supplying fuel to the second fuel manifold; and supplying pressurized air to the second fuel manifold to flush fuel in the second fuel manifold into the combustor and hinder coking in the second fuel manifold and associated fuel nozzles.

Methods and systems of operating a gas turbine engine in a low-power condition are provided. In one embodiment, the method includes supplying fuel to a combustor by supplying fuel to a first fuel manifold and a second fuel manifold of the gas turbine engine. The method also includes, while supplying fuel to the combustor by supplying fuel to the first fuel manifold: stopping supplying fuel to the second fuel manifold; and supplying pressurized air to the second fuel manifold to flush fuel in the second fuel manifold into the combustor and hinder coking in the second fuel manifold and associated fuel nozzles.

A gas turbine engine for an aircraft comprises a high-pressure (HP) spool comprising an HP compressor and a first electric machine driven by an HP turbine; a low-pressure (LP) spool comprising an LP compressor and a second electric machine driven by an LP turbine; a combustion system comprising a fuel metering unit; and an engine controller configured to, in response to a change of a power lever angle setting indicative of a deceleration event, reduce fuel flow to the combustion system by the fuel metering unit, and to operate the first electric machine in a generator mode to reduce the HP spool rotational speed and engine core mass flow.

A gas turbine engine for an aircraft comprises a high-pressure (HP) spool comprising an HP compressor and a first electric machine driven by an HP turbine; a low-pressure (LP) spool comprising an LP compressor and a second electric machine driven by an LP turbine; a combustion system comprising a fuel metering unit; and an engine controller configured to, in response to a change of a power lever angle setting indicative of a deceleration event, reduce fuel flow to the combustion system by the fuel metering unit, and to operate the first electric machine in a generator mode to reduce the HP spool rotational speed and engine core mass flow.

A method for controlling a fuel metering device with a movable metering element, comprising at least two iterations of the following steps: a detection (E1) of a possible change in the operating state among two position sensors of the metering element, if no change in the operating state is detected, a determination (E2_1) of the position of the metering element from an average of the measurements of the sensors or otherwise a determination (E2_2) from the non-defective sensor, a determination (E4) of a fuel flow rate setpoint, a conversion (E5) of the flow rate setpoint, a determination (E6) of a command of displacement of the metering element, a control (E7) of the position of the metering element, and

if a change in the operating state is detected, the calculation of an instantaneous fuel flow rate from the position of the metering element, and, during the second iteration of the method, the determination of the flow rate setpoint according to instantaneous flow rate to match the position setpoint to the position of the metering element.

A method for controlling a fuel metering device with a movable metering element, comprising at least two iterations of the following steps: a detection (E1) of a possible change in the operating state among two position sensors of the metering element, if no change in the operating state is detected, a determination (E2_1) of the position of the metering element from an average of the measurements of the sensors or otherwise a determination (E2_2) from the non-defective sensor, a determination (E4) of a fuel flow rate setpoint, a conversion (E5) of the flow rate setpoint, a determination (E6) of a command of displacement of the metering element, a control (E7) of the position of the metering element, and

if a change in the operating state is detected, the calculation of an instantaneous fuel flow rate from the position of the metering element, and, during the second iteration of the method, the determination of the flow rate setpoint according to instantaneous flow rate to match the position setpoint to the position of the metering element.

A method and system for cleaning a fuel nozzle during engine operation is provided. Operations include operating the compressor section to provide the flow of oxidizer at a first oxidizer flow condition to the combustion chamber, wherein the first oxidizer flow condition comprises an environmental parameter; operating the fuel system at a first fuel flow condition to produce a fuel-oxidizer ratio at the combustion chamber; comparing the environmental parameter to a first environmental parameter threshold; and transitioning the fuel system to a second fuel flow condition corresponding to a cleaning condition at the fuel nozzle if the environmental parameter is equal to or greater than the first environmental threshold.

A method and system for cleaning a fuel nozzle during engine operation is provided. Operations include operating the compressor section to provide the flow of oxidizer at a first oxidizer flow condition to the combustion chamber, wherein the first oxidizer flow condition comprises an environmental parameter; operating the fuel system at a first fuel flow condition to produce a fuel-oxidizer ratio at the combustion chamber; comparing the environmental parameter to a first environmental parameter threshold; and transitioning the fuel system to a second fuel flow condition corresponding to a cleaning condition at the fuel nozzle if the environmental parameter is equal to or greater than the first environmental threshold.

A gas turbine includes: multiple fuel systems; a combustor that combusts fuels from the multiple fuel systems in compressed air to generate combustion gas; and a turbine that is driven by the combustion gas. A flow volume ratio calculation device which calculates the flow volume ratio of the fuels flowing in the multiple fuel systems includes calculators that receive values of a first parameter and a second parameter capable of expressing the combustion state in the combustor, and that calculate the flow volume ratio relative to the received values of the two parameters from a predetermined relationship between the two parameters and the flow volume ratio.

A method for controlling a fuel metering device with a movable metering element, comprising at least two iterations of the following steps: a detection (E1) of a possible change in the operating state among two position sensors of the metering element, if no change in the operating state is detected, a determination (E2_1) of the position of the metering element from an average of the measurements of the sensors or otherwise a determination (E2_2) from the non-defective sensor, a determination (E4) of a fuel flow rate setpoint, a conversion (E5) of the flow rate setpoint, a determination (E6) of a command of displacement of the metering element, a control (E7) of the position of the metering element, and if a change in the operating state is detected, the calculation of an instantaneous fuel flow rate from the position of the metering element, and, during the second iteration of the method, the determination of the flow rate setpoint according to instantaneous flow rate to match the position setpoint to the position of the metering element.