A convergent-divergent nozzle arranged to convey fluid from an upstream zone to a downstream zone via a throat aperture, wherein the nozzle includes an assembly movable to vary the size of the throat aperture of the nozzle, thereby regulating the flow of fluid to the downstream zone.

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.

A control system for a variable area fan nozzle (VAFN) having a plurality of petals is disclosed. The control system may include at least one fiber optic shape sensor extending along at least one of the plurality of petals, and a light source operatively connected to the at least one fiber optic shape sensor. The control system may further include a receiver operatively connected to the at least one fiber optic shape sensor. The control system may further include a VAFN control unit in operative communication with the plurality of petals and the receiver. The VAFN control unit may be configured to receive a signal from the receiver indicative of the measured strain along the at least one fiber optic shape sensor, and calculate a nozzle area of the VAFN based on the measured strain.

A control system for a variable area fan nozzle (VAFN) having a plurality of petals is disclosed. The control system may include at least one fiber optic shape sensor extending along at least one of the plurality of petals, and a light source operatively connected to the at least one fiber optic shape sensor. The control system may further include a receiver operatively connected to the at least one fiber optic shape sensor. The control system may further include a VAFN control unit in operative communication with the plurality of petals and the receiver. The VAFN control unit may be configured to receive a signal from the receiver indicative of the measured strain along the at least one fiber optic shape sensor, and calculate a nozzle area of the VAFN based on the measured strain.

A method of designing a turbofan engine according to an exemplary aspect of the present disclosure includes, among other things, providing a fan section including a plurality of fan blades, providing a low pressure turbine driving the plurality of fan blades through a gear train, providing a fan nacelle and a core nacelle, the fan nacelle at least partially surrounding the core nacelle, providing a fan bypass flow path defined between the core nacelle and the fan nacelle, and providing 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.

A method of designing a turbofan engine according to an exemplary aspect of the present disclosure includes, among other things, providing a fan section including a plurality of fan blades, providing a low pressure turbine driving the plurality of fan blades through a gear train, providing a fan nacelle and a core nacelle, the fan nacelle at least partially surrounding the core nacelle, providing a fan bypass flow path defined between the core nacelle and the fan nacelle, and providing 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.

A turbofan engine includes fan section including a plurality of fan blades, a gear train, a low spool including a low pressure turbine and a low pressure compressor, the low pressure turbine driving the plurality of fan blades through the gear train, and a high spool including a high pressure turbine driving a high pressure compressor. A fan nacelle at least partially surrounds a core nacelle to define a fan bypass flow path. A fan variable area nozzle is in communication with the fan bypass flow path and defines a fan nozzle exit area between the fan nacelle and the core nacelle. The fan variable area nozzle varies the fan nozzle exit area.

A turbofan engine includes fan section including a plurality of fan blades, a gear train, a low spool including a low pressure turbine and a low pressure compressor, the low pressure turbine driving the plurality of fan blades through the gear train, and a high spool including a high pressure turbine driving a high pressure compressor. A fan nacelle at least partially surrounds a core nacelle to define a fan bypass flow path. A fan variable area nozzle is in communication with the fan bypass flow path and defines a fan nozzle exit area between the fan nacelle and the core nacelle. The fan variable area nozzle varies the fan nozzle exit area.

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.