Abstract: A nacelle for a gas turbine engine includes a ring shaped body defining a center axis and having a radially outward surface and a radially inward surface. An aft portion of the radially inward surface includes an axially extending convergent-divergent exit nozzle. An axially extending secondary duct passes through the nacelle in the convergent-divergent exit nozzle. The axially extending secondary duct includes an inlet at a convergent portion of the convergent-divergent exit nozzle and an outlet at a divergent portion of the convergent-divergent exit nozzle.

Abstract: A gas turbine engine includes a core engine that has at least a compressor section, a combustor section and a turbine section disposed along a central axis. A fan is coupled to be driven by the turbine section. A fan nozzle is aft of the fan and defines an exit area. The fan nozzle has a body with an airfoil cross-section geometry. The body includes a wall that has a controlled mechanical property distribution that varies in material macro- or micro-structure by location on the wall in accordance with a desired flutter characteristic at the location.

Abstract: A turbofan engine includes a fan section. A core engine section drives the fan section. An outer nacelle surrounds the fan section and defines a radially outer surface of a fan duct. An inner nacelle surrounds the core engine section and defines a radially inner surface of the fan duct. A nozzle is disposed at a terminal end of the outer nacelle that defines an exit area for bypass air flow through the fan duct. The nozzle includes a convergent portion forward of a divergent portion and a turning angle for the divergent portion greater than about 12 degrees. A nacelle assembly and method are also disclosed.

Abstract: A gas turbine engine includes a core engine that has at least a compressor section, a combustor section and a turbine section disposed along a central axis. A fan is coupled to be driven by the turbine section. A fan nozzle is aft of the fan and defines an exit area. The fan nozzle has a body with an airfoil cross-section geometry. The body includes a wall that has a controlled mechanical property distribution that varies in material macro- or micro-structure by location on the wall in accordance with a desired flutter characteristic at the location.

Abstract: A nacelle for a gas turbine engine includes a ring shaped body defining a center axis and having a radially outward surface and a radially inward surface. An aft portion of the radially inward surface includes an axially extending convergent-divergent exit nozzle. An axially extending secondary duct passes through the nacelle in the convergent-divergent exit nozzle. The axially extending secondary duct includes an inlet at a convergent portion of the convergent-divergent exit nozzle and an outlet at a divergent portion of the convergent-divergent exit nozzle.

Abstract: A gas turbine engine includes a core engine that has at least a compressor section, a combustor section and a turbine section disposed along a central axis. A fan is coupled to be driven by the turbine section. A fan nozzle is aft of the fan and defines an exit area. The fan nozzle has a body that defines an airfoil cross-section geometry. The body includes a wall that has a controlled mechanical property distribution that varies by location on the wall in accordance with a desired flutter characteristic at the location.

Abstract: A nacelle for a gas turbine engine includes a ring shaped body defining a center axis and having a radially outward surface and a radially inward surface. An aft portion of the radially inward surface includes an axially extending convergent-divergent exit nozzle. An axially extending secondary duct passes through the nacelle in the convergent-divergent exit nozzle. The axially extending secondary duct includes an inlet at a convergent portion of the convergent-divergent exit nozzle and an outlet at a divergent portion of the convergent-divergent exit nozzle.

Abstract: A gas turbine engine includes a core engine that has at least a compressor section, a combustor section and a turbine section disposed along a central axis. A fan is coupled to be driven by the turbine section. A fan nozzle is aft of the fan and defines an exit area. The fan nozzle has a body that defines an airfoil cross-section geometry. The body includes a wall that has a controlled mechanical property distribution that varies by location on the wall in accordance with a desired flutter characteristic at the location.

Abstract: A method of controlling flutter of a fan nozzle includes, for a given design of a fan nozzle, determining a vibration mode that causes a flutter characteristic of the fan nozzle and, in response to the determined vibration mode, establishing a wall thickness distribution of at least one wall of the fan nozzle to include local thick portions and local thin portions that alter the flutter characteristic.

Abstract: A gas turbine engine includes a core engine that has at least a compressor section, a combustor section and a turbine section disposed along a central axis. A fan is coupled to be driven by the turbine section. A fan nacelle is arranged around the fan, and a bypass passage extends between the fan nacelle and the core engine. A variable area fan nozzle (VAFN) extends at least partially around the central axis and defines an exit area of the bypass passage. The VAFN is selectively movable to vary the exit area. The VAFN includes a body that defines an airfoil cross-section shape. The VAFN includes a wall that has a mechanical property distribution in accordance with a computer-simulated vibration profile of a flutter characteristic of the VAFN.

Abstract: A nacelle for a gas turbine engine includes a ring shaped body defining a center axis and having a radially outward surface and a radially inward surface. An aft portion of the radially inward surface includes an axially extending convergent-divergent exit nozzle. An axially extending secondary duct passes through the nacelle in the convergent-divergent exit nozzle. The axially extending secondary duct includes an inlet at a convergent portion of the convergent-divergent exit nozzle and an outlet at a divergent portion of the convergent-divergent exit nozzle.

Abstract: A turbofan engine includes a fan section. A core engine section drives the fan section. An outer nacelle surrounds the fan section and defines a radially outer surface of a fan duct. An inner nacelle surrounds the core engine section and defines a radially inner surface of the fan duct. A nozzle is disposed at a terminal end of the outer nacelle that defines an exit area for bypass air flow through the fan duct. The nozzle includes a convergent portion forward of a divergent portion and a turning angle for the divergent portion greater than about 12 degrees. A nacelle assembly and method are also disclosed.

Abstract: A nacelle structure for a gas turbine engine includes a core engine nacelle disposed about an engine axis and an outer nacelle disposed about the core engine nacelle. A bifurcation extends between the outer nacelle and the core engine nacelle along a bifurcation axis extending between the outer nacelle and the core engine nacelle. The bifurcation includes at least one mounting surface that is disposed at a non-normal angle relative to the bifurcation axis.

Abstract: A method of controlling flutter of a fan nozzle includes, for a given design of a fan nozzle, determining a vibration mode that causes a flutter characteristic of the fan nozzle and, in response to the determined vibration mode, establishing a wall thickness distribution of at least one wall of the fan nozzle to include local thick portions and local thin portions that alter the flutter characteristic.

Abstract: A nacelle structure for a gas turbine engine includes a core engine nacelle disposed about an engine axis and an outer nacelle disposed about the core engine nacelle. A bifurcation extends between the outer nacelle and the core engine nacelle along a bifurcation axis extending between the outer nacelle and the core engine nacelle. The bifurcation includes at least one mounting surface that is disposed at a non-normal angle relative to the bifurcation axis.

Abstract: A variable area fan nozzle for a gas turbine engine includes a radially outer wall and a radially inner wall. At least one of the radially outer wall and the radially inner wall includes a wall thickness distribution that has local thick portions and local thin portions.