Variable volume combustor with pre-nozzle fuel injection system

1. A combustor for use with a gas turbine engine, comprising:

a liner;

a cap assembly;

a seal in between the liner and the cap assembly;

a head end with a head end volume;

a combustion zone with a combustion zone volume;

a plurality of fuel nozzles positioned within the cap assembly;

a pre-nozzle fuel injection system supporting the plurality of fuel nozzles, wherein the pre-nozzle fuel injection system separates the head end from the combustion zone; and

a linear actuator to maneuver the plurality of fuel nozzles and the pre-nozzle fuel injection system, such that the head end volume is increased as the combustion zone volume is decreased.

2. The combustor of claim 1 , wherein the plurality of fuel nozzles comprises a plurality of micro-mixer fuel nozzles.

3. The combustor of claim 1 , further comprising a common fuel tube in communication with the pre-nozzle fuel injection system.

4. The combustor of claim 1 , wherein the pre-nozzle fuel injection system comprises a fuel nozzle manifold.

5. The combustor of claim 4 , wherein the fuel nozzle manifold comprises a center hub.

6. The combustor of claim 1 , wherein the pre-nozzle fuel injection system comprises a plurality of support struts supporting the plurality of fuel nozzles.

7. The combustor of claim 6 , wherein the plurality of support struts comprises a substantially aerodynamically contoured shape.

8. The combustor of claim 6 , wherein the plurality of support struts is positioned upstream of the plurality of fuel nozzles.

9. The combustor of claim 6 , wherein the plurality of support struts comprises a plurality of fuel injections holes.

10. The combustor of claim 9 , wherein the plurality of support struts comprises a first side wall and a second side wall and wherein the plurality of fuel injection holes is positioned thereon.

11. The combustor of claim 9 , wherein a pre-nozzle fuel flow passes through the plurality of fuel injection holes.

12. The combustor of claim 11 , wherein the pre-nozzle flow comprises about twenty percent or less of a flow of fuel to the plurality of fuel nozzles.

13. The combustor of claim 1 , wherein the linear actuator comprises a drive rod in communication with the pre-nozzle fuel injection system.

14. A method of operating a combustor in a gas turbine engine, the combustor comprising a liner, a cap assembly, and a seal in between the liner and the cap assembly, the method comprising:

supporting a plurality of fuel nozzles about a plurality of support struts, the plurality of fuel nozzles positioned within the cap assembly;

flowing a flow of fuel through the plurality of support struts to the plurality of fuel nozzles;

actuating the plurality of fuel nozzles from a first position to a second position, such that a head end volume of the combustor is increased as a combustion zone volume of the combustor is decreased;

diverting a pre-nozzle flow of fuel from the plurality of support struts;

flowing a flow of air through the plurality of support struts; and

mixing the flow of air and the pre-nozzle flow of fuel upstream of the plurality of fuel nozzles.

15. A combustor for use with a gas turbine engine, comprising:

a liner;

a cap assembly;

a seal in between the liner and the cap assembly;

a head end with a head end volume;

a combustion zone with a combustion zone volume;

a plurality of micro-mixer fuel nozzles positioned within the cap assembly;

a plurality of support struts supporting the plurality of micro-mixer fuel nozzles;

the plurality of support struts comprising a plurality of fuel injections holes thereon; and

a linear actuator to maneuver the plurality of micro-mixer fuel nozzles and the plurality of support struts, such that the head end volume is increased as the combustion zone volume is decreased.

16. The combustor of claim 15 , wherein the plurality of support struts comprises a substantially aerodynamically contoured shape.

17. The combustor of claim 15 , wherein the plurality of support struts is positioned upstream of the plurality of fuel nozzles.

18. The combustor of claim 15 , wherein the plurality of support struts comprises a first side wall and a second side wall and wherein the plurality of fuel injection holes is positioned thereon.

19. The combustor of claim 15 , wherein a pre-nozzle fuel flow passes through the plurality of fuel injection holes.