Variable volume combustor with center hub fuel staging

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

a plurality of micro-mixer fuel nozzles; and

a fuel injection system for providing a flow of fuel to the plurality of micro-mixer fuel nozzles;

the fuel injection system comprising a center hub comprising a plurality of fuel circuits therein for providing the flow of fuel therethrough;

wherein the center hub comprises a first supply circuit therein for a first micro-mixer fuel nozzle of the plurality of micro-mixer fuel nozzles and a second supply circuit therein for a second micro-mixer fuel nozzle of the plurality of micro-mixer fuel nozzles, wherein the fuel injection system comprises a plurality of support struts extending radially from the center hub to a cap assembly, wherein the plurality of support struts comprise at least one support strut disposed upstream from the first and second micro-mixer fuel nozzles, wherein the second micro-mixer fuel nozzle extends towards a combustion zone from a downstream end of the at least one first support strut, wherein a flow of fuel in the second supply circuit passes through the center hub and into the at least one first support strut where it is then supplied to the second micro-mixer fuel nozzle.

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

3. The combustor of claim 1 , wherein the plurality of support struts comprises an aerodynamic shape.

4. The combustor of claim 1 , wherein the first micro-mixer fuel nozzle comprises a center micro-mixer fuel nozzle.

5. The combustor of claim 1 , wherein the second micro-mixer fuel nozzle comprises an outer micro-mixer fuel nozzle.

6. The combustor of claim 5 , wherein the outer micro-mixer fuel nozzle comprises a first set of outer micro-mixer fuel nozzles.

7. The combustor of claim 5 , wherein the outer micro-mixer fuel nozzle comprises a second set of outer micro-mixer fuel nozzles.

8. The combustor of claim 1 , wherein the fuel injection system is in communication with a common fuel tube with the first supply circuit and the second supply circuit therein.

9. The combustor of claim 8 , further comprising a nested fuel manifold in communication with the common fuel tube with the first supply circuit and the second supply circuit therein.

10. The combustor of claim 8 , further comprising an end cover and wherein the common fuel tube comprises a single entry port through the end cover.

11. The combustor of claim 1 , wherein the center hub comprises a third supply circuit therethrough for a third micro-mixer fuel nozzle of the plurality of micro-mixer fuel nozzles.

12. The combust of claim 1 , further comprising a linear actuator to maneuver the plurality of micro-mixer fuel nozzles and the center hub.

13. A fuel injection system for a combustor for use with a gas turbine engine, comprising:

a plurality of micro-mixer fuel nozzles;

one or more of the plurality of micro-mixer fuel nozzles extending from a plurality of support struts; and

the plurality of support struts extending radially from a center hub to a cap assembly;

wherein the center hub comprises a first supply circuit therein for a first micro-mixer fuel nozzle of the plurality of micro-mixer fuel nozzles and a second supply circuit therein for a second micro-mixer fuel nozzle of the plurality of micro-mixer fuel nozzles, wherein the plurality of support struts comprise a first support strut disposed between the wherein the plurality of support struts comprise at least one first support strut disposed upstream from the first and second micro-mixer fuel nozzles, wherein the second micro-mixer fuel nozzle extends towards a combustion zone from a downstream end of the at least one first support strut, wherein a flow of fuel in the second supply circuit passes through the center hub and into the at least one first support strut where it is then supplied to the second micro-mixer fuel nozzle.

14. The fuel injection system of claim 13 , wherein the plurality of micro-mixer fuel nozzles comprises a plurality of micro-mixer fuel tubes and a fuel plate.

15. The fuel injection system of claim 14 , wherein the first micro-mixer fuel nozzle comprises a center micro-mixer fuel nozzle.

16. The fuel injection system of claim 14 , wherein the second micro-mixer fuel nozzle comprises an outer micro-mixer fuel nozzle.

17. The fuel injection system of claim 16 , wherein the outer micro-mixer fuel nozzle comprises a set of outer micro-mixer fuel nozzles.

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

a plurality of micro-mixer fuel nozzles;

a fuel injection system for providing a flow of fuel to the plurality of micro-mixer fuel nozzles;

the fuel injection system comprising a center hub comprising a plurality of fuel circuits therein for providing the flow of fuel therethrough;

a plurality of support struts extending radially from the center hub to a cap assembly, wherein the plurality of support struts are disposed upstream from the plurality of micro-mixer fuel nozzles, wherein at least one of the plurality of micro-mixer fuel nozzles extends towards a combustion zone from a downstream end of at least one of the plurality of support struts, wherein the flow of fuel in at least one of the plurality of fuel circuits passes through the center hub and into at least one of the plurality of support struts where it is then supplied to at least one of the plurality of micro-mixer fuel nozzles; and

a linear actuator to maneuver the plurality of micro-mixer fuel nozzles, the center hub, and the plurality of support struts.