Gas turbine engine with axial movable fan variable area nozzle

1. A nacelle assembly for a high-bypass gas turbine engine comprising:

a core nacelle defined about an engine centerline axis;

a fan nacelle mounted at least partially around said core nacelle to define a fan bypass flow path for a fan bypass airflow; and

a fan variable area nozzle that defines a trailing edge of the fan nacelle and is axially movable relative said fan nacelle between an open position and a closed position to open an auxiliary port and to vary a fan nozzle exit area such that bypass airflow flows concurrently through both the auxiliary port and the fan nozzle exit area to adjust a pressure ratio of the fan bypass airflow during engine operation, wherein the fan variable area nozzle includes a chord length and a radial outer wall surface that is at a radial distance from the engine centerline axis and a ratio of the radial distance to the chord length is greater than 0.7.

2. The assembly as recited in claim 1 , further comprising a controller operable to control said fan variable area nozzle to vary a fan nozzle exit area and adjust the pressure ratio of the fan bypass airflow, wherein said controller is one of an engine controller and an aircraft flight control system.

3. The assembly as recited in claim 2 , wherein said controller is operable to reduce said fan nozzle exit area at a cruise flight condition.

4. The assembly as recited in claim 2 , wherein said controller is operable to control said fan nozzle exit area to reduce a fan instability.

5. The assembly as recited in claim 1 , further comprising a controller operable to axially move said fan variable area nozzle to vary said fan nozzle exit area in response to a flight condition, wherein the controller is one of an engine controller and an aircraft flight control system.

6. The assembly as recited in claim 5 , wherein said fan variable area nozzle is aligned with said fan nacelle to define a closed position of said fan nozzle exit area.

7. The assembly as recited in claim 6 , wherein said fan variable area nozzle is axially offset from the fan nacelle to define the open position of said fan nozzle exit area.

8. The assembly as recited in claim 1 , further comprising a gear system driven by a core engine within the core nacelle to drive a fan within the fan nacelle, said gear system defines a gear reduction ratio of greater than or equal to about 2.3.

9. The assembly as recited in claim 1 , further comprising a gear system driven by a core engine within the core nacelle to drive a fan within the fan nacelle, said gear system defines a gear reduction ratio of greater than or equal to about 2.5.

10. The assembly as recited in claim 1 , further comprising a gear system driven by said core engine to drive a fan, said gear system defines a gear reduction ratio of greater than or equal to 2.5.

11. The assembly as recited in claim 8 , wherein said core engine includes a low pressure turbine which defines a pressure ratio that is greater than about five (5).

12. The assembly as recited in claim 8 , wherein said core engine includes a low pressure turbine which defines a pressure ratio that is greater than five (5).

13. The assembly as recited in claim 1 , wherein said bypass flow defines a bypass ratio greater than about six (6).

14. The assembly as recited in claim 1 , wherein said bypass flow defines a bypass ratio greater than about ten (10).

15. The assembly as recited in claim 1 , wherein said bypass flow defines a bypass ratio greater than ten (10).

16. The nacelle assembly as recited in claim 1 , wherein the fan variable area nozzle includes a first fan nacelle section and a second fan nacelle section movable relative to the first fan nacelle section with the second nacelle section and the auxiliary port is defined between the first fan nacelle section and the second fan nacelle section that doubles a fan exit area gain due to translation of the second fan nacelle section.

17. The nacelle assembly as recited in claim 1 , wherein the second fan nacelle section defines an entrance angle of the auxiliary port that is less than about 20 degrees relative to a radially outer surface of the bypass flow path.

18. A gas turbine engine comprising:

a core nacelle defined about an engine centerline axis;

a fan nacelle mounted at least partially around said core nacelle to define a fan bypass flow path for a fan bypass airflow;

a fan variable area nozzle defines a trailing edge of the fan nacelle and is axially movable relative said fan nacelle between an open position and a closed position to open an auxiliary port and to vary a fan nozzle exit area such that bypass airflow flows concurrently through both the auxiliary port and the fan nozzle exit area to adjust a pressure ratio of the fan bypass airflow during engine operation, the fan variable area nozzle includes a chord length and a radial outer wall surface that is at a radial distance from the engine centerline axis and a ratio of the radial distance to the chord length is greater than 0.7; and

a controller operable to control said fan variable area nozzle to vary a fan nozzle exit area and adjust the pressure ratio of the fan bypass airflow.

19. The gas turbine engine of claim 18 , wherein said gas turbine engine is a direct drive turbofan engine.

20. The gas turbine engine of claim 18 , wherein said gas turbine further comprises a low spool within said core nacelle that drives a fan within said fan nacelle through a geared architecture.

21. The gas turbine engine of claim 20 , wherein the engine has a bypass ratio greater than 10:1 and the geared architecture has a gear reduction ratio of greater than 2.5:1.

22. The gas turbine engine as recited in claim 18 , wherein the fan variable area nozzle includes a first fan nacelle section and a second fan nacelle section movable relative to the first fan nacelle section with the second nacelle section and the auxiliary port is defined between the first fan nacelle section and the second fan nacelle section that doubles fan exit area gain due to translation of the second fan nacelle section.

23. The gas turbine engine as recited in claim 22 , wherein the second fan nacelle section defines an entrance angle of the auxiliary port that is less than about 20 degrees relative to a radially outer surface of the bypass flow path.