A propulsion unit for an aircraft includes a nacelle, a turbojet engine, an annular flow path for circulating a secondary air flow, and a precooler device communicating with a motor enclosure and including a scoop opening into the annular flow path. The propulsion unit includes a compressed air supply circuit arranged in the propulsion unit for injecting a flow of compressed air into the scoop of the precooler device. A method for ventilating a motor enclosure of a propulsion unit includes injecting compressed air into a scoop of the precooler device when the turbojet engine is stopped.

A turbofan engine has a fan portion in fluid communication with a core stream and a bypass stream of air separated by splitters disposed both upstream and downstream of the fan portion. A blade splitter (shroud) on the fan partially spans the fan blade thus separating the core and bypass streams downstream while leaving a gap upstream for communication between the flows. The communication gap expands the operational range of the fan over fans without the communication gap.

A turboshaft engine includes a core engine, including a fan section, a compressor section, a primary combustor and a turbine section positioned within a core flow path of the gas turbine engine; a bypass splitter positioned radially outward of the core engine and configured to house the compressor section, the primary combustor and the turbine section; a bypass duct positioned radially outward of the bypass splitter; and a power spool operably coupled to the core engine and configured rotationally drive a fan included within the fan section.

Vehicles, such as aircraft, may include turbine-based combined cycle power plants (TBCC) for power to achieve high-mach speeds. An anti-unstart configuration provides control for transitioning between the amount of air directed to either engine during operation of gas turbine engine and scramjet engines, to avoid unstart during operation above sonic speeds.

Vehicles, such as aircraft, may include turbine-based combined cycle power plants (TBCC) for power to achieve high-mach speeds. An anti-unstart configuration provides control for transitioning between the amount of air directed to either engine during operation of gas turbine engine and scramjet engines, to avoid unstart during operation above sonic speeds.

A nacelle assembly of a gas turbine engine includes an annular structure defining a central axis, and having a radially inward surface and a radially outward surface, the radially inward surface at least partially defining a bypass duct. An aft portion of the radially inward surface at least partially defines an axially extending convergent-divergent exit nozzle. A secondary nozzle flap is radially spaced from the aft portion of the radially inward surface. The secondary nozzle flap and the aft portion of the radially inward surface define a secondary bypass duct therebetween. The secondary nozzle flap is operably connected to the annular structure such that the secondary nozzle flap is selectably movable relative to the aft portion of the radially inward surface, thereby changing a cross-sectional area of a secondary bypass duct exit.

A nacelle assembly of a gas turbine engine includes an annular structure defining a central axis, and having a radially inward surface and a radially outward surface, the radially inward surface at least partially defining a bypass duct. An aft portion of the radially inward surface at least partially defines an axially extending convergent-divergent exit nozzle. A secondary nozzle flap is radially spaced from the aft portion of the radially inward surface. The secondary nozzle flap and the aft portion of the radially inward surface define a secondary bypass duct therebetween. The secondary nozzle flap is operably connected to the annular structure such that the secondary nozzle flap is selectably movable relative to the aft portion of the radially inward surface, thereby changing a cross-sectional area of a secondary bypass duct exit.

A system for modulating air flow in a gas turbine engine is provided. The system may include a seal wall comprising an opening, a seal door configured to slideably engage the seal wall, and an actuator configured to move the seal door over the opening. In various embodiments, the system may include a surface forward of the seal door. The seal door may be configured to seal a passage through the surface and the opening of the seal wall. A track may be disposed under the seal door. The track may comprise cobalt. Rollers may be coupled to the seal door with the rollers on the track. The seal door may comprise a nickel-chromium alloy. A sync ring may be coupled to the seal door. The actuator may be coupled through the sync ring to the seal door.

A system for modulating air flow in a gas turbine engine is provided. The system may include a seal wall comprising an opening, a seal door configured to slideably engage the seal wall, and an actuator configured to move the seal door over the opening. In various embodiments, the system may include a surface forward of the seal door. The seal door may be configured to seal a passage through the surface and the opening of the seal wall. A track may be disposed under the seal door. The track may comprise cobalt. Rollers may be coupled to the seal door with the rollers on the track. The seal door may comprise a nickel-chromium alloy. A sync ring may be coupled to the seal door. The actuator may be coupled through the sync ring to the seal door.

A system for modulating air flow in a gas turbine engine is provided. The system may include a seal wall comprising an opening, a seal door configured to slideably engage the seal wall, and an actuator configured to move the seal door over the opening. In various embodiments, the system may include a surface forward of the seal door. The seal door may be configured to seal a passage through the surface and the opening of the seal wall. A track may be disposed under the seal door. The track may comprise cobalt. Rollers may be coupled to the seal door with the rollers on the track. The seal door may comprise a nickel-chromium alloy. A sync ring may be coupled to the seal door. The actuator may be coupled through the sync ring to the seal door.