Variable fan nozzle using shape memory material

1. A gas turbine engine comprising:

a fan disposed about an engine axis;

a nacelle arranged about the fan;

an engine core at least partially within the nacelle, the engine core having a compressor and a turbine;

a fan bypass passage downstream of the fan between the nacelle and the engine core, for conveying a bypass airflow from the fan;

a nozzle section disposed about the engine axis for controlling the bypass airflow, wherein the nozzle section includes a shape memory material disposed at least partially around an internal cavity and defining a radial inner side and a radial outer side of the internal cavity, the shape memory material having a first solid state phase that corresponds to a first nozzle position and a second solid state phase that corresponds to a second nozzle position; and

an actuator at least partially within the internal cavity, the actuator having a radiant heating element that includes wires for selectively heating the internal cavity and the shape memory material.

2. The gas turbine engine recited in claim 1 , wherein the shape memory material comprises a threshold temperature that corresponds to a reversible change between the first solid state phase and the second solid state phase.

3. The gas turbine engine recited in claim 1 , wherein the shape memory material comprises a nickel-titanium alloy.

4. The gas turbine engine recited in claim 1 , wherein the shape memory material comprises a material selected from a copper alloy, a nickel alloy, a cobalt alloy, a manganese alloy, a copper-aluminum alloy, a copper-zinc-aluminum alloy, and combinations thereof.

5. The gas turbine engine of claim 1 , wherein the nozzle includes tabs that include the shape memory material.

6. The gas turbine engine recited in claim 5 , wherein the tabs extend from the nacelle in a generally axial direction relative to an axis of rotation of the fan.

7. The gas turbine engine recited in claim 5 , wherein the tabs taper from a forward end toward a trailing end.

8. The gas turbine engine recited in claim 1 , wherein the nozzle section moves in an axial direction between the first nozzle position and the second nozzle position.

9. The gas turbine engine recited in claim 1 , wherein the nozzle section moves in a radial direction between the first nozzle position and the second nozzle position.

10. The gas turbine engine recited in claim 1 , wherein the shape memory material comprises a cobalt alloy.

11. The gas turbine engine recited in claim 1 , wherein the shape memory material consists of a cobalt alloy.

12. The gas turbine engine recited in claim 1 , wherein the nozzle varies an effective area associated with the nozzle by approximately 20% to influence the bypass airflow.

13. The gas turbine engine recited in claim 1 , wherein a single actuator heats the wires extending through multiple internal cavities.

14. The gas turbine engine recited in claim 5 , wherein the tabs are only shape memory material.

15. The gas turbine engine recited in claim 5 , wherein the internal cavity tapers with a taper of walls of the tabs.

16. The gas turbine engine recited in claim 5 , wherein the wires includes multiple loops that form a heating mesh to uniformly heat the tabs.

17. The gas turbine engine recited in claim 5 , wherein each tab of the tabs includes one of a plurality of actuators.

18. A variable fan nozzle for use in a gas turbine engine, comprising:

a nozzle section for influencing a bypass airflow associated with a fan bypass passage, the nozzle section including a shape memory material disposed at least partially around an internal cavity and defining a radial inner side and a radial outer side of the internal cavity, the shape memory material having a first solid state phase that corresponds to a first nozzle position and a second solid state phase that corresponds to a second nozzle position, and an actuator at least partially within the internal cavity, the actuator having a radiant heating element that includes wires for selectively heating the internal cavity and the shape memory material.

19. A method for controlling a bypass airflow through a nozzle associated with a fan bypass passage in a gas turbine engine, comprising the steps of:

controlling a radiant heating element within an internal cavity of the nozzle to provide a desired temperature within the internal cavity; and

controlling the desired temperature to selectively reversibly transition a shape memory material, disposed at least partially around the internal cavity of the nozzle and defining a radial inner side and a radial outer side of the internal cavity, relative to a threshold temperature associated with the shape memory material, where the reversible transitioning includes transitioning between a first solid state phase and a second solid state phase of the shape memory material to move the nozzle between a first position corresponding to the first solid state phase and a second position corresponding to the second solid state phase.

20. The method recited in claim 19 , further including reversibly transitioning between the first solid state phase and the second solid state phase to change an effective area of the nozzle.

21. The method recited in claim 19 , further including reversibly transitioning between the first solid state phase and the second solid state phase to move the nozzle in an axial direction between the first position and the second position relative to a central axis of the gas turbine engine.

22. The method recited in claim 19 , further including reversibly transitioning between the first solid state phase and the second solid state phase to move the nozzle in a radial direction between the first position and the second position relative to a central axis of the gas turbine engine.