Methods and systems to facilitate reducing NO

1. A method for assembling a gas turbine combustor system, said method comprising:

providing a combustion liner including a center axis, an outer wall, a first end, and a second end, wherein the outer wall orientated substantially parallel to the center axis and having a first end and a second end having substantially the same cross-sectional area;

coupling a transition piece to the liner second end, wherein the transition piece includes an outer wall having a first end with a first cross-sectional area and a second end with a second cross-sectional area such that the transition piece is substantially frustoconical in shape; and

coupling a plurality of lean-direct injectors along the liner outer wall and the transition piece outer wall such that the injectors are spaced axially apart along the liner outer wall and the transition piece outer wall.

2. A method in accordance with claim 1 further comprising coupling at least one premixing injector adjacent to the liner first end.

3. A method in accordance with claim 1 further comprising coupling at least one lean-direct injector adjacent to the liner first end.

4. A method in accordance with claim 1 further comprising coupling an end cap to the liner first end.

5. A method in accordance with claim 4 further comprising coupling at least one premixing injector to the end cap.

6. A method in accordance with claim 4 further comprising coupling at least one lean-direct injector to the end cap.

7. A method in accordance with claim 1 wherein each of the lean-direct injectors includes at least one air injector and at least one fuel injector, said method further comprises orientating each air injector and each fuel injector such that air and fuel flows discharged therefrom impinge within the combustion liner.

8. A method in accordance with claim 7 further comprising:

defining a plurality of openings in the liner outer wall and the transition piece outer wall; and

orientating the openings to be in flow communication with the at least one air injector and the at least one fuel injector of a respective lean-direct injector.

9. A method for distributing air and fuel in a gas turbine combustor system comprising:

providing a combustion liner including a center axis, an outer wall, a first end, and a second end, wherein the outer wall is orientated substantially parallel to the center axis and having a first end and a second end having substantially the same cross-sectional area;

coupling a transition piece to the liner second end, wherein the transition piece includes an outer wall having a first end with a first cross-sectional area and a second end with a second cross-sectional area such that the transition piece is substantially frustoconical in shape; and

axially staging air and fuel injection through a plurality of lean-direct injectors spaced axially along the liner outer wall and the transition piece outer wall.

10. A method in accordance with claim 9 wherein axially staging air and fuel injection further comprises injecting air and fuel separately into the at least one liner outer wall and transition piece outer wall.

11. A method in accordance with claim 10 wherein axially staging air and fuel injection further comprises injecting air and fuel from a respective lean-direct injector based on an operating condition of the gas turbine system.

12. A gas turbine combustor system comprising:

a combustion liner comprising a center axis, an outer wall, a first end, and a second end, said outer wall is orientated substantially parallel to the center axis and having a first end and a second end having substantially the same cross-sectional area;

a transition piece coupled to said liner second end, said transition piece comprising an outer wall having a first end with a first cross-sectional area and a second end with a second cross-sectional area such that the transition piece is substantially frustoconical in shape; and

a plurality of lean-direct injectors spaced axially along said liner outer wall and said transition piece outer wall.

13. A gas turbine combustor system in accordance with claim 12 further comprising at least one premixing injector coupled adjacent to said liner first end.

14. A gas turbine combustor system in accordance with claim 12 further comprising at least one lean-direct injector coupled adjacent said liner first end.

15. A gas turbine combustor system in accordance with claim 12 further comprising an end cap coupled to said liner first end.

16. A gas turbine combustor system in accordance with claim 15 further comprising at least one premixing injector coupled to said end cap.

17. A gas turbine combustor system in accordance with claim 15 further comprising at least one lean-direct injector coupled to said end cap.

18. A gas turbine combustor system in accordance with claim 12 wherein each of said lean-direct injectors comprises:

at least one air injector configured to introduce air flow within said combustor liner; and

at least one fuel injector configured to fuel within said combustion liner such that the fuel mixes with the air.

19. A gas turbine combustor system in accordance with claim 18 wherein said at least one air injector and said at least one fuel injector are orifices defined in at least one of said liner outer wall and said transition piece outer wall.

20. A gas turbine combustor system in accordance with claim 18 wherein at least one of said combustion liner and said transition piece comprises a plurality of openings defined therein, said openings are in flow communication with said at least one air injector and said at least one fuel injector.