Method for cooling a thermal protection floor of an aft aerodynamic fairing of a structure for mounting an aircraft propulsion system
A propulsion system for an aircraft, including a dual-flow turbojet and a mounting structure for mounting this turbojet on the wing surface or on the fuselage of an aircraft. The mounting structure includes an aft aerodynamic fairing including a thermal protection floor to protect the mounting structure from the heat of a primary airstream channelled by an exhaust nozzle of the turbojet, as well as an air inlet provided in a longitudinal aerodynamic wall washed by a secondary airstream of the turbojet and delimiting together with an other similar wall a cavity isolated from the secondary airstream for extracting a cooling airstream from the secondary airstream, and air circulation means fed by the air inlet and having at least one outlet aperture emerging in a space between the thermal protection floor and the exhaust nozzle.
1. A propulsion system for an aircraft, including a dual-flow turbojet and a mounting structure intended to mount said turbojet to the wing surface or to the fuselage of the aircraft, said mounting structure including an aft aerodynamic fairing including a thermal protection floor to protect said mounting structure from heat of a primary airstream channeled by an exhaust nozzle of said turbojet, said propulsion system comprising:
extraction means for extracting a cooling airstream from a secondary airstream of said turbojet, together with an air circulator fed by said extraction means, said air circulator having at least one outlet aperture emerging into a space defined by a gap between said thermal protection floor and said exhaust nozzle, the outlet aperture is located upstream from a trailing edge of the exhaust nozzle,
wherein said extraction means include at least one air inlet connected to said air circulator and formed in an aerodynamic wall of said propulsion system, said aerodynamic wall being followed by said secondary airstream during operation, said aerodynamic wall extending longitudinally opposite another similar aerodynamic wall of said propulsion system, said aerodynamic wall delimiting with said another similar aerodynamic wall a cavity separated from said secondary airstream,
wherein said aerodynamic fairing extends in an extension of a bifurcation formed of two bifurcation walls mutually connecting two annular nacelle cases respectively internally and externally delimiting an annular space for the secondary airstream to flow in said turbojet, and said aerodynamic walls being said bifurcation walls or side walls of said aft aerodynamic fairing.
2. A propulsion system according to claim 1 , wherein said air circulator includes at least one pipe extending at least partly in said cavity.
3. A propulsion system according to claim 1 , wherein said outlet aperture of said air circulator has an air ejection axis which is parallel to a front end portion of said thermal protection floor.
4. A propulsion system according to claim 1 , wherein said outlet aperture of said air circulator traverses said thermal protection floor.
5. A propulsion system according to claim 1 , including side sealing joints which laterally delimit said space between said thermal protection floor and said exhaust nozzle.
6. An aircraft including at east one propulsion system according to claim 1 .
7. A method of cooling a thermal protection floor of an aft aerodynamic fairing of a structure for mounting a propulsion system according to claim 1 , in which cooling air is extracted from the secondary airstream of the turbojet of said propulsion system by said extraction means, and is injected into said space comprised between said thermal protection floor and said exhaust nozzle of the turbojet by said air circulator.
8. A method according claim 7 , wherein the cooling air is injected into said space in a direction parallel to said thermal protection floor so as to form a cooling film of air between said thermal protection floor and said primary airstream of the turbojet.