Gas turbine transition inlet ring adapter

1. A combustion system for a gas turbine engine, comprising:

a combustor assembly comprising a combustor basket having a liner and a downstream terminal end; a transition duct extending downstream from the combustor basket and having an upstream end located adjacent to the downstream terminal end of the combustor basket;

an inlet ring adapter affixed to the upstream end of the transition duct, the inlet ring adapter extending downstream of the upstream end of the transition duct in overlapping relation to an inner surface of the transition duct;

a spring clip assembly mounted to the downstream terminal end of the combustor basket and resiliently biased into engagement with an inwardly facing surface of the inlet ring adapter forming a coupling between the combustor basket and the transition duct; and

wherein the transition duct is a single piece that has a radial step wall at the upstream end to define a first larger diameter adjacent to a cylindrical sleeve of the inlet ring adapter and a second smaller diameter extending in a direction distal from the inlet ring adapter, wherein the radial step wall extends perpendicularly from the inner surface of the transition duct to a second inner surface of the transition duct; and

wherein the cylindrical sleeve of the inlet ring adapter extends generally parallel to the transition duct between the liner and the inlet ring adapter, and comprises a flange portion extending perpendicular to the cylindrical sleeve and attached to the upstream end of the transition duct.

2. The system of claim 1 , wherein the flange portion is formed with apertures for receiving removable fasteners.

3. The system of claim 2 , wherein the upstream end of the transition duct includes threaded holes for receiving fasteners received through the apertures in the flange portion.

4. The system of claim 3 , including a bolt ring affixed to the upstream end of the transition duct and including the threaded holes, the bolt ring defining a radial thickness that is greater than a radial thickness of the upstream end of the transition duct.

5. The system of claim 4 , wherein the bolt ring is welded to the upstream end of the transition duct.

6. The system of claim 4 , wherein the bolt ring is formed integral with the upstream end of the transition duct.

7. The system of claim 1 , wherein the inwardly facing surface of the inlet ring adapter defines an inner diameter that is greater than the second smaller diameter of the transition duct.

8. The system of claim 1 , wherein the sleeve of the inlet ring adapter includes a distal downstream end that is located adjacent to the radial step of the transition duct to effect a reduction in recirculation flow at the radial step.

9. A combustion system for a gas turbine engine, comprising:

a combustor assembly comprising a combustor basket having a liner and a downstream terminal end;

a transition duct extending downstream from the combustor basket and having an upstream end located adjacent to the downstream terminal end of the combustor basket;

a coupling comprising:

an inlet ring adapter including a cylindrical sleeve extending downstream of the upstream end of the transition duct in overlapping relation to an inner surface of the transition duct; and

a spring clip assembly mounted to the downstream terminal end of the combustor basket, the spring clip assembly extending into engagement with and forming a seal on the cylindrical sleeve;

wherein the transition duct is a single piece that has a radial step wall at the upstream end to define a first larger diameter adjacent to the cylindrical sleeve and a second smaller diameter extending in a direction distal from the cylindrical sleeve; wherein the radial step wall extends perpendicularly from the inner surface of the transition duct to a second inner surface of the transition duct; and

wherein the cylindrical sleeve of the inlet ring adapter extends generally parallel to the transition duct between the liner and the inlet ring adapter, and comprises a flange portion extending perpendicular to the cylindrical sleeve and attached to the upstream end of the transition duct.

10. The system of claim 9 , wherein the cylindrical sleeve is spaced radially inwardly from the inner surface of the transition duct.

11. The system of claim 9 , wherein the cylindrical sleeve is mounted on the transition duct with removable fasteners.

12. The system of claim 11 , including a flange portion extending radially outwardly from the cylindrical sleeve, and apertures formed through the flange portion for receiving the removable fasteners.

13. The system of claim 12 , including a bolt ring welded to the upstream end of the transition duct, and including threaded holes for receiving the removable fasteners.

14. The system of claim 9 , wherein at least a portion of the spring clip assembly is resiliently biased into engagement with an inwardly facing surface of the cylindrical sleeve.

15. The system of claim 9 , wherein an inwardly facing surface of the cylindrical sleeve defines an inner diameter that is greater than the second smaller diameter of the transition duct.

16. The system of claim 9 , wherein the cylindrical sleeve includes a distal downstream end that is located adjacent to the radial step of the transition duct to effect a reduction in recirculation flow at the radial step.