A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan section including a plurality of fan blades, the plurality of fan blades having a fixed stagger angle and a design angle of incidence, a low pressure turbine driving the plurality of fan blades through a gear train, a fan nacelle and a core nacelle extending along an engine axis of rotation, the fan nacelle at least partially surrounding the core nacelle and the plurality of fan blades, a fan bypass flow path defined between the core nacelle and the fan nacelle, the core nacelle contoured along the fan bypass flow path with respect to the engine axis of rotation, and a fan variable area nozzle in communication with a controller and with the fan bypass flow path, and defining a fan nozzle exit area between the fan nacelle and the core nacelle.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan section including a plurality of fan blades, the plurality of fan blades having a fixed stagger angle and a design angle of incidence, a low pressure turbine driving the plurality of fan blades through a gear train, a fan nacelle and a core nacelle extending along an engine axis of rotation, the fan nacelle at least partially surrounding the core nacelle and the plurality of fan blades, a fan bypass flow path defined between the core nacelle and the fan nacelle, the core nacelle contoured along the fan bypass flow path with respect to the engine axis of rotation, and a fan variable area nozzle in communication with a controller and with the fan bypass flow path, and defining a fan nozzle exit area between the fan nacelle and the core nacelle.

A variable area nozzle assembly includes a fixed center plug, a fixed outer nozzle, and an inner nozzle. The fixed center plug includes a seal. The inner nozzle is disposed between the fixed center plug and the fixed outer nozzle. The inner nozzle includes an inner nozzle body. The inner nozzle body forms a primary duct between the inner nozzle and the fixed outer nozzle. The inner nozzle body forms a secondary duct and a gap. The gap is a nozzle outlet of the secondary duct. The secondary duct is disposed between the inner nozzle body and the fixed center plug upstream of the seal. The inner nozzle body forms a plurality of apertures. The inner nozzle body is translatable between a first position and a second position. In the first position, the primary duct has a first cross-sectional area and the plurality of apertures are isolated from the gap by the seal. In the second position, the primary duct has a second cross-sectional area and the plurality of apertures are connected in fluid communication with the gap.

A variable area nozzle assembly includes a fixed center plug, a fixed outer nozzle, and an inner nozzle. The fixed center plug includes a seal. The inner nozzle is disposed between the fixed center plug and the fixed outer nozzle. The inner nozzle includes an inner nozzle body. The inner nozzle body forms a primary duct between the inner nozzle and the fixed outer nozzle. The inner nozzle body forms a secondary duct and a gap. The gap is a nozzle outlet of the secondary duct. The secondary duct is disposed between the inner nozzle body and the fixed center plug upstream of the seal. The inner nozzle body forms a plurality of apertures. The inner nozzle body is translatable between a first position and a second position. In the first position, the primary duct has a first cross-sectional area and the plurality of apertures are isolated from the gap by the seal. In the second position, the primary duct has a second cross-sectional area and the plurality of apertures are connected in fluid communication with the gap.

A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

A fan nacelle, a gas turbine engine cell assembly, and an aircraft are provided. The fan nacelle includes a fan duct skin arranged in a fan duct to direct airflow from the fan of a Turbofan engine toward a fan nozzle. An exterior skin of the fan nacelle directs air flow around an exterior of the engine. The fan duct skin and the exterior skin terminate at a trailing edge, and a trailing edge portion of the exterior skin is one of parallel to and diverging from a trailing edge portion of the fan duct skin in an aft direction. In certain aspects, the trailing edge portion of the exterior skin is actuatable or inflatable to selectively divert from the trailing edge portion of the fan duct skin.

A fan nacelle, a gas turbine engine cell assembly, and an aircraft are provided. The fan nacelle includes a fan duct skin arranged in a fan duct to direct airflow from the fan of a Turbofan engine toward a fan nozzle. An exterior skin of the fan nacelle directs air flow around an exterior of the engine. The fan duct skin and the exterior skin terminate at a trailing edge, and a trailing edge portion of the exterior skin is one of parallel to and diverging from a trailing edge portion of the fan duct skin in an aft direction. In certain aspects, the trailing edge portion of the exterior skin is actuatable or inflatable to selectively divert from the trailing edge portion of the fan duct skin.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan section including a plurality of fan blades, the plurality of fan blades having a fixed stagger angle and a design angle of incidence, a low pressure turbine driving the plurality of fan blades through a gear train, a fan nacelle and a core nacelle extending along an engine axis of rotation, the fan nacelle at least partially surrounding the core nacelle and the plurality of fan blades, a fan bypass flow path defined between the core nacelle and the fan nacelle, the core nacelle contoured along the fan bypass flow path with respect to the engine axis of rotation, and a fan variable area nozzle in communication with a controller and with the fan bypass flow path, and defining a fan nozzle exit area between the fan nacelle and the core nacelle.