Staged fuel and air injection in combustion systems of gas turbines

1. A gas turbine that comprises:

a combustor coupled to a turbine that together define a working fluid flowpath, the working fluid flowpath extending aftward along a longitudinal axis from a forward end defined by a forward injector in the combustor, through an interface at which the combustor transitions to the turbine, and then through the turbine to an aftward end defined therein, wherein the combustor includes an inner radial wall, which defines the working fluid flowpath, and an outer radial wall, which is formed about the inner radial wall such that a flow annulus is formed therebetween;

a compressor discharge cavity formed about the combustor for receiving a combustor air supply delivered thereto by a compressor;

a staged injection system that includes the forward injector and, axially spaced aftward therefrom, a staged injector, wherein the staged injector intersects the flow annulus so to attain an injection point within the working fluid flowpath, and wherein, relative an axial position of the injection point, an aftward annulus section is defined to an aftward side of the injection point and a forward annulus section is defined to a forward side of the injection point;

fuel directing structure for apportioning a combustor fuel supply between the forward injector and the staged injector; and

air directing structure for apportioning the combustor air supply between the forward injector and the staged injector;

wherein the air directing structure comprises axially defined intake sections formed through the outer radial wall that fluidly connect the compressor discharge cavity to corresponding axially defined sections of the flow annulus, the intake sections including an aftward intake section that corresponds to the aftward annulus section and a forward intake section that corresponds to the forward annulus section; and

wherein the air directing structure is configured to:

direct air entering through the aftward intake section through the aftward annulus section in a forward direction to the staged injector; and

direct air entering through the forward intake section through the forward annulus section in a forward direction to the forward injector;

further comprising an axial partition positioned in the flow annulus so to approximately axially coincide with the staged injector;

wherein the axial partition comprises a wall that extends between the outer radial wall and the inner radial wall and about a circumference of the flow annulus so to seal the flow annulus against fluid communication between the aftward annulus section and the forward annulus section.

2. The gas turbine according to claim 1 , wherein the combustor comprises reference planes including: a forward reference plane, a mid reference plane, an aftward reference plane, and a staged injector reference plane, each of which comprising reference planes aligned substantially perpendicular to the longitudinal axis of the working fluid flowpath, wherein:

the forward reference plane aligns with the forward end of the working fluid flowpath;

the aftward reference plane aligns with the interface at which the combustor transitions to the turbine;

the mid reference plane aligns with an axial midpoint between of the working fluid flowpath between the forward and aftward reference plane; and

the staged injector reference plane aligns with the injection point of the staged injector; and

wherein:

the aftward intake section comprises an axial range defined approximately between the staged injector reference plane and the aftward reference plane; and

the forward intake section comprises an axial range defined approximately between the staged injector reference plane and the forward reference plane.

3. The gas turbine according to claim 2 , wherein:

the aftward intake section comprises a plurality of spaced impingement ports, each formed through the outer radial wall for training an impinged air jet against an outer surface of the inner radial wall; and

the forward intake section comprises a plurality of spaced impingement ports, each formed through the outer radial wall for training an impinged air jet against the outer surface of the inner radial wall.

4. The gas turbine according to claim 3 , wherein:

the plurality of impingement ports of the aftward intake section are axially spaced between an aftward most impingement port positioned just forward of the aftward reference plane and a forward most impingement port positioned just aftward of the injector reference plane;

the plurality of impingement ports of the forward intake section are axially spaced between an aftward most impingement port positioned just forward of the injector reference plane and a forward most impingement port positioned just aftward of the forward reference plane; and

wherein the plurality of impingement ports of each of the aftward and the forward intake sections are spaced circumferentially about substantially all of a circumference of the outer radial wall.

5. The gas turbine according to claim 4 , wherein the staged injector is positioned between the forward reference plane and the mid reference plane.

6. The gas turbine according to claim 4 , wherein the staged injector is positioned approximately at the mid reference plane.

7. The gas turbine according to claim 4 , wherein the staged injector is positioned just forward of the aftward reference plane.

8. The gas turbine according to claim 4 , wherein the staged injector is positioned approximately midway between the mid reference plane and the aftward reference plane.

9. The gas turbine according to claim 4 , further comprising a plurality of the staged injectors that are spaced circumferentially about the injector reference plane; and

wherein each of the plurality of the staged injectors has corresponding ones of the aftward and the forward intake sections that angularly align therewith.

10. The gas turbine according to claim 4 , wherein the inner radial wall comprises axially stacked chambers defined therewithin, the axially stacked chambers including a forward chamber that houses the forward injector and an aftward chamber that defines a combustion zone; and

wherein a nozzle of the staged injector intersects the flow annulus so to attain the injection point; and

wherein the nozzle includes a tube extending between the outer radial wall and the inner radial wall, the tube blocking a portion of the flow annulus.

11. The gas turbine according to claim 10 , wherein the staged injector comprises an air port formed through the tube of the nozzle, the air port fluidly connecting the flow annulus to an interior of the tube; and

wherein the fuel directing structure includes:

a fuel passageway extending axially from a fuel source positioned near the headend of the combustor; and

fuel ports formed through the tube of the nozzle that fluidly connect the fuel passageway to the interior of the tube.

12. The gas turbine according to claim 11 , wherein the air port is disposed on an aftward face of the tube and is configured for collecting an airflow from the aftward annulus section;

wherein the fuel ports are circumferentially spaced about an inner circumference of the tube of the nozzle; and

wherein the fuel passageway extends axially through an interior of the outer radial wall.

13. The gas turbine according to claim 11 , wherein the combustor air supply comprises a total supply of air delivered to the compressor discharge cavity;

wherein the air directing structure comprises relative orifice sizing between the aftward intake section, the forward intake section, and the headend intake section for metering the supply air to the combustor between the forward injector and the staged injector; and

wherein the metering the combustor air supply includes directing at least 20% of the air supply to the combustor to the staged injector.

14. The gas turbine according to claim 11 , wherein the combustor air supply comprises a total supply of air delivered to the compressor discharge cavity;

wherein the air directing structure comprises relative orifice sizing between the aftward intake section, the forward intake section, and the headend intake section for metering the supply air to the combustor between the forward injector and the staged injector; and

wherein the metering the combustor air supply includes directing at least 40% of the air supply to the combustor to the staged injector.

15. The gas turbine according to claim 11 , wherein:

the aftward annulus section comprises heat transfer structure for increasing a rate of heat transfer occurring between an airflow moving therethrough and an outer surface of the inner radial wall; and

the forward annulus section comprises the heat transfer structure for increasing a rate of heat transfer occurring between an airflow moving therethrough and the outer surface of the inner radial wall.

16. The gas turbine according to claim 15 , wherein the heat transfer structure comprises turbulators formed on the outer surface of the inner radial wall.

17. The gas turbine according to claim 15 , wherein the heat transfer structure comprises microchannels formed on the outer surface of the inner radial wall.

18. The gas turbine according to claim 15 , wherein each of the microchannels comprises an axially aligned shallow channel that includes an inlet port and outlet port opening to the flow annulus and an enclosed section positioned therebetween.

19. The gas turbine according to claim 11 ,

wherein the axial partition is configured for fluidly sealing the forward annulus section from the aftward annulus section such that:

all of the air of the combustor air supply flowing into the forward annulus section is directed to the forward injector; and

all of the air of the combustor air supply flowing into the aftward annulus section is directed to the staged injector.

20. The gas turbine according to claim 2 , wherein the combustor is configured as one of: a can-annular combustor; and an annular combustor.