Three stream, variable area fixed aperture nozzle with pneumatic actuation

1. A variable internal exhaust area nozzle for a gas turbine engine, comprising:

a plurality of flap trains extending around a periphery of the gas turbine engine, with each flap train including a convergent flap pivotally attached to an engine body and a divergent flap pivotally attached to the engine body downstream of the convergent flap; and

a fluid circuit in communication with the convergent and divergent flaps and configured to pivot the convergent and divergent flaps between a radially inward position and a radially outward position;

wherein the convergent flap has a closing pressure chamber selectively communicating with a closing portion of the fluid circuit, and the convergent flap is configured to move radially outward in response to the closing pressure chamber receiving a working fluid from the closing portion of the fluid circuit;

wherein the divergent flap has a closing pressure chamber selectively communicating with a closing portion of the fluid circuit, and the divergent flap is configured to move radially outward in response to the closing pressure chamber receiving a working fluid from the closing portion of the fluid circuit.

2. The variable internal exhaust area nozzle of claim 1 , wherein the convergent flap has a closing pressure chamber selectively communicating with a closing portion of the fluid circuit, and the convergent flap is configured to move radially outward in response to the closing pressure chamber receiving a working fluid from the closing portion of the fluid circuit.

3. The variable internal exhaust area nozzle of claim 2 , wherein the closing pressure chamber is configured to vent the working fluid in response to the convergent flap moving radially inward.

4. The variable internal exhaust area nozzle of claim 1 , wherein the convergent flap has an opening pressure chamber selectively communicating with an opening portion of the fluid circuit, and the convergent flap is configured to move radially inward in response to the opening pressure chamber receiving a working fluid from the opening portion of the fluid circuit.

5. The variable internal exhaust area nozzle of claim 4 , wherein the opening pressure chamber is configured to vent the working fluid in response to the convergent flap moving radially outward.

6. The variable internal exhaust area nozzle of claim 1 , wherein the divergent flap has a closing pressure chamber selectively communicating with a closing portion of the fluid circuit, and the divergent flap is configured to move radially outward in response to the closing pressure chamber receiving a working fluid from the closing portion of the fluid circuit.

7. The variable internal exhaust area nozzle of claim 6 , wherein the closing pressure chamber is configured to vent the working fluid in response to the divergent flap moving radially inward.

8. The variable internal exhaust area nozzle of claim 1 , wherein the divergent flap has an opening pressure chamber selectively communicating with an opening portion of the fluid circuit, and the divergent flap is configured to move radially outward in response to the opening pressure chamber receiving a working fluid from the opening portion of the fluid circuit.

9. The variable internal exhaust area nozzle of claim 8 , wherein the opening pressure chamber is configured to vent the working fluid in response to the divergent flap moving radially outward.

10. The variable internal exhaust area nozzle of claim 1 , further comprising a plurality of side walls that separate the plurality of flap trains adjacent to each other in a circumferential direction.

11. A variable internal exhaust area nozzle for a gas turbine engine, comprising:

a plurality of flap trains extending around a periphery of the gas turbine engine, with each flap train including a convergent flap pivotally attached to an engine body and a divergent flap pivotally attached to the engine body downstream of the convergent flap;

a fluid circuit in communication with the convergent and divergent flaps and configured to pivot the convergent and divergent flaps between a radially inward position and a radially outward position; and

a plurality of side walls that separate the plurality of flap trains adjacent to each other in a circumferential direction, the plurality of side walls extending from one axial end of the nozzle to at least a region between the convergent flap and the divergent flap;

wherein the nozzle is configured to provide a fixed exit aperture.

12. The variable internal exhaust area nozzle of claim 11 , wherein the fixed exit aperture is formed by one of an external shroud and an external housing surrounding the convergent flaps and the divergent flaps.

13. The variable internal exhaust area nozzle of claim 11 , wherein each of the convergent flaps and the divergent flaps has a closing pressure chamber selectively communicating with a closing portion of the fluid circuit, and the flaps are configured to move radially outward in response to the closing pressure chamber receiving a working fluid from the closing portion of the fluid circuit.

14. The variable internal exhaust area nozzle of claim 11 , wherein each of the convergent flaps and the divergent flaps has an opening pressure chamber selectively communicating with an opening portion of the fluid circuit, and the flaps are configured to move radially inward in response to the opening pressure chamber receiving a working fluid from the opening portion of the fluid circuit.

15. The variable internal exhaust area nozzle of claim 11 , wherein each of the convergent flaps and the divergent flaps has an opening pressure chamber configured to vent a working fluid in response to the divergent flap moving radially outward and a closing pressure chamber configured to vent the working fluid in response to the divergent flap moving radially inward.

16. A variable internal exhaust area nozzle for a gas turbine engine, comprising:

a plurality of flap trains extending around a periphery of the gas turbine engine, with each flap train including a convergent flap pivotally attached to an engine body and a divergent flap pivotally attached to the engine body downstream of the convergent flap; and

a fluid circuit in communication with the convergent and divergent flaps and configured to pivot the convergent and divergent flaps between a radially inward position and a radially outward position;

wherein the convergent flap has a closing pressure chamber selectively communicating with a closing portion of the fluid circuit, and the convergent flap is configured to move radially outward in response to the closing pressure chamber receiving a working fluid from the closing portion of the fluid circuit;

wherein the divergent flap has a closing pressure chamber selectively communicating with a closing portion of the fluid circuit, and the divergent flap is configured to move radially outward in response to the closing pressure chamber receiving a working fluid from the closing portion of the fluid circuit;

wherein the nozzle defines a throat configured to pass a primary stream;

wherein the nozzle further defines a series of variable area passages spaced apart from each other along a periphery of the throat;

wherein the nozzle further defines a series of fixed area passages spaced apart from each other along the periphery of the throat, such that the nozzle is configured to bifurcate a third stream flow; and

wherein the fluid circuit is one of a pneumatic circuit and a hydraulic circuit.

17. The variable internal exhaust area nozzle of claim 16 , wherein the bifurcated third stream flow includes a fixed area third stream exhausted from a heat exchanger and passing through the series of fixed area passages.

18. The variable internal exhaust area nozzle of claim 16 , wherein the bifurcated third stream flow includes a variable area third stream bypassing a heat exchanger and passing through the series of variable area passages.

19. The variable internal exhaust area nozzle of claim 16 , wherein the variable area passages alternate with the fixed area passages about the periphery of the throat.

20. The variable internal exhaust area nozzle of claim 16 , wherein the nozzle is configured to provide a fixed exit aperture.