A control system operable includes a modified primary control parameter for an aircraft, the control system includes: a primary control parameter leg configured to output a demand in an aircraft primary control parameter; a primary control parameter compensation leg configured to receive a change in absolute levels and/or spatial distributions of swirl angle and/or fan pressure at a primary control parameter relative to a reference and convert the change into the primary control parameter; a processor adapted to receive the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; compare the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; and generate a modified primary control parameter for the aircraft.

A method of estimating a parameter of a fluid flowing in a passage includes: having a plurality of instruments operable to measure one or more fluid properties flowing in the passage, the plurality of instruments being disposed in the passage and arranged within a common measurement plane; assigning a stream tube to each instrument, each stream tube represents a region of space in the common measurement plane within the passage and each stream tube surrounds one of the plurality of instruments, the stream tubes together correspond to the cross-sectional shape and area of the passage in the common measurement plane; measuring the one or more fluid properties using the instruments to obtain one or more measured values for each stream tube; using the measured value(s) for each stream tube to calculate a derived value for each stream tube; and summing the derived values across all of the stream tubes.

An assembly is provided for a turbofan engine. This turbofan engine assembly includes a cowling, a door and an actuation mechanism configured to actuate movement of the door in response to receiving a control signal. The cowling is configured to form a compartment at least partially around a case of the turbofan engine. The cowling includes an exhaust port that is fluidly coupled with the compartment. The door is configured to at least partially open and close the exhaust port. This variable exhaust port may be opened in case increased airflow is needed through the compartment, such as when increased cooling airflow is needed through an environmental air precooler that cools compressed air for the aircraft cabin and the precooler exhausts its cooling air into the compartment.

An assembly is provided for a turbofan engine. This turbofan engine assembly includes a cowling, a door and an actuation mechanism configured to actuate movement of the door in response to receiving a control signal. The cowling is configured to form a compartment at least partially around a case of the turbofan engine. The cowling includes an exhaust port that is fluidly coupled with the compartment. The door is configured to at least partially open and close the exhaust port. This variable exhaust port may be opened in case increased airflow is needed through the compartment, such as when increased cooling airflow is needed through an environmental air precooler that cools compressed air for the aircraft cabin and the precooler exhausts its cooling air into the compartment.

A gas turbine engine having a forward thrust mode and a reverse thrust mode is provided. The gas turbine engine includes a variable pitch fan configured for generating forward thrust in the forward thrust mode of the engine and reverse thrust in the reverse thrust mode of the engine. The engine also includes a fan cowl surrounding the variable pitch fan, wherein the fan cowl forms a bypass duct for airflow generated by the fan. The fan cowl includes an aft edge that defines a physical flow area of the bypass duct, and a deflection device configured for deflecting airflow near the aft edge, wherein the deflection device is configured for operation in the reverse thrust mode of the engine. The physical flow area of the bypass duct at the aft edge remains the same in the forward thrust mode of the engine and in the reverse thrust mode of the engine.

A gas turbine engine having a forward thrust mode and a reverse thrust mode is provided. The gas turbine engine includes a variable pitch fan configured for generating forward thrust in the forward thrust mode of the engine and reverse thrust in the reverse thrust mode of the engine. The engine also includes a fan cowl surrounding the variable pitch fan, wherein the fan cowl forms a bypass duct for airflow generated by the fan. The fan cowl includes an aft edge that defines a physical flow area of the bypass duct, and a deflection device configured for deflecting airflow near the aft edge, wherein the deflection device is configured for operation in the reverse thrust mode of the engine. The physical flow area of the bypass duct at the aft edge remains the same in the forward thrust mode of the engine and in the reverse thrust mode of the engine.

A variable geometry exhaust nozzle arrangement includes a plurality of hingable exhaust petals defining a perimeter of an exhaust duct and an annular ring slidably engagable against a radially outer surface of each petal. The annular ring is coupled to a plurality of circumferentially spaced actuator arrangements, each including first and second circumferentially spaced parallel actuator arms pivotably coupled to the annular ring at a first end and to a slide arrangement at a second end. Each slide arrangement is mounted for linear sliding movement relative to the annular ring, such that sliding movement of each slide arrangement causes pivoting of the first and second actuator arms to thereby translate the annular ring in one or both of a longitudinal direction and a lateral direction.

A system for a thrust reverser of an aircraft includes a primary sleeve and a secondary sleeve having cascades. The secondary sleeve is coupled to a set of blocker doors. The sliding motions of the primary sleeve and the secondary sleeve are not directly coupled when each moves between its stowed and deployed positions. The sliding motion of the primary sleeve may begin at a different time and continue at a different rate from the sliding motion of the secondary sleeve.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan section including a plurality of fan blades, a gear train, a low pressure turbine driving the fan section through the gear train, a fan nacelle and a core nacelle, the fan nacelle at least partially surrounding the core nacelle, a fan bypass flow path defined between the core nacelle and the fan nacelle, and a fan variable area nozzle in communication with the fan bypass flow path, and defining a fan nozzle exit area between the fan nacelle and the core nacelle. The fan variable area nozzle includes a first fan nacelle section and a second fan nacelle section, the second fan nacelle section movably mounted relative the first fan nacelle section and moveable axially along an engine axis of rotation relative the first fan nacelle section, defining an auxiliary port that extends between the first fan nacelle section and the second fan nacelle section.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan section including a plurality of fan blades, a gear train, a low pressure turbine driving the fan section through the gear train, a fan nacelle and a core nacelle, the fan nacelle at least partially surrounding the core nacelle, a fan bypass flow path defined between the core nacelle and the fan nacelle, and a fan variable area nozzle in communication with the fan bypass flow path, and defining a fan nozzle exit area between the fan nacelle and the core nacelle. The fan variable area nozzle includes a first fan nacelle section and a second fan nacelle section, the second fan nacelle section movably mounted relative the first fan nacelle section and moveable axially along an engine axis of rotation relative the first fan nacelle section, defining an auxiliary port that extends between the first fan nacelle section and the second fan nacelle section.