Ducting arrangement with injector assemblies configured to form a shielding flow of air injected into a combustion stage in a gas turbine engine

1. An injector assembly disposed in a combustion stage of a combustion turbine engine, the combustion stage fluidly coupled to receive a cross-flow of combustion products, the injector assembly comprising:

a reactant-guiding structure comprising an inner wall and an outer wall, the reactant-guiding structure arranged to convey a flow of fuel/air mixture to admix with the cross-flow of combustion products; and

a passageway defined between the inner wall and the outer wall, the passageway comprising an inlet side and an outlet side, the inner wall circumferentially wrapping around the outer wall at the inlet side, the passageway configured to inject a flow of air arranged to condition interaction of the flow of fuel/air mixture with the cross-flow of combustion products.

2. The injector assembly of claim 1 , wherein the flow of air is arranged to form a boundary of air flow that surrounds the flow of fuel/air mixture, as the flow of fuel/air mixture is admitted in the combustion stage.

3. The injector assembly of claim 2 , wherein the boundary of air flow that surrounds the flow of fuel/air mixture is effective to transitorily shield the flow of fuel/air mixture conveyed to the combustion stage from the cross-flow of combustion products, and thus provide an ignition delay to the flow of fuel/air mixture injected into the combustion stage.

4. The injector assembly of claim 1 , wherein the injector assembly is one of a plurality of injector assemblies, wherein the plurality of injector assemblies are arranged circumferentially spaced apart from each other in a transition duct.

5. The injector assembly of claim 4 , wherein at least some of the plurality of injector assemblies are disposed at different axial locations in the transition duct.

6. The injector assembly of claim 1 , wherein the outlet side of the passageway comprises a uniform cross-sectional profile along a perimeter of the outlet side of the passageway.

7. The injector assembly of claim 1 , wherein the outlet side of the passageway comprises a varying cross-sectional profile along a perimeter of the outlet side of the passageway so that a velocity and a volume of the flow of air have a desired variation along the perimeter of the outlet side of the passageway.

8. The injector assembly of claim 1 , wherein the outlet side of the passageway comprises geometric features configured to promote co-flow intermixing of the flow of air with the flow of fuel/air mixture, as each flow is respectively admitted into the combustion stage.

9. The injector assembly of claim 1 , wherein the passageway comprises a first helical rib for swirling the flow of air to be injected into the combustion stage.

10. The injector assembly of claim 1 , wherein the reactant-guiding structure comprises a second helical rib for swirling the flow of fuel/air mixture to be injected into the combustion stage.

11. The injector assembly of claim 1 , wherein the passageway comprises a first helical rib for swirling the flow of air along a first swirl direction, wherein the reactant-guiding structure comprises a second helical rib for swirling the flow of fuel/air mixture along a second swirl direction, wherein the first and the second swirl directions comprise opposite swirling directions relative to one another.

12. The injector assembly of claim 1 , wherein the passageway comprises a first helical rib for swirling the flow of air along a first swirl direction, wherein the reactant-guiding structure comprises a second helical rib for swirling the flow of fuel/air mixture along a second swirl direction, wherein the first and the second swirl directions comprise equal swirling directions relative to one another.

13. The injector assembly of claim 1 , further comprising orifices arranged on the inner wall.

14. A ducting arrangement comprising:

a combustor wall in a combustion stage of a combustion turbine engine, the combustion stage fluidly coupled to receive a cross-flow of combustion products;

an injector assembly disposed in the combustor wall, the injector assembly comprising a reactant-guiding structure comprising an inner wall and an outer wall, the reactant-guiding structure arranged to convey a flow of fuel/air mixture to admix with the cross-flow of combustion products, wherein the injector assembly includes a passageway defined between the inner wall and the outer wall, the passageway comprising an inlet side and an outlet side, the inner wall circumferentially wrapping around the outer wall at the inlet side, the passageway configured to inject a flow of air arranged for conditioning interaction of the flow of fuel/air mixture with the cross-flow of combustion products, the interaction conditioning based on a boundary formed by the flow of air that surrounds the flow of fuel/air mixture and is effective to provide an ignition delay to the flow of fuel/air mixture injected into the combustion stage.

15. The ducting arrangement of claim 14 , wherein the combustor wall comprises a multi-panel arrangement that includes a plurality of cooling air conduits in fluid communication with the passageway in the injector assembly to convey air that passes through the plurality of cooling air conduits to the passageway and form the flow of air to be injected.

16. The ducting arrangement of claim 14 , wherein the combustor wall comprises a unitized structure that includes a plurality of cooling air conduits in fluid communication with the passageway in the injector assembly to convey air that passes through the plurality of cooling air conduits to the passageway and form the flow of air to be injected.

17. The ducting arrangement of claim 14 , wherein the injection assembly comprises a unitized structure.

18. The ducting arrangement of claim 14 , comprising a unitized structure.