Late lean injection with adjustable air splits

1. A gas turbine engine comprising:

a combustor having a first interior in which a first fuel supplied thereto by a fuel circuit is combustible;

a turbine, including rotating turbine blades, into which products of at least the combustion of the first fuel are receivable to power the rotation of the turbine blades;

a transition zone, including a second interior in which a second fuel supplied thereto by the fuel circuit and the products of the combustion of the first fuel are combustible, the transition zone being disposed to fluidly couple the combustor and the turbine to one another;

a plurality of fuel injectors, which are structurally supported by the transition zone and coupled to the fuel circuit, and which are configured to supply the second fuel to the second interior in any one of a single axial stage, multiple axial stages, a single axial circumferential stage and multiple axial circumferential stages;

a compressor, fluidly coupled to the combustor and the transition zone, by which air is supplied to the first and second interiors for the combustion therein; and

a control system coupled to the fuel circuit and configured to control relative amounts of the air to the first and second interiors and relative amounts of the first and second fuels supplied by the fuel circuit to the first and second interiors.

2. The gas turbine engine according to claim 1 , wherein the control system comprises:

a system of valves, at least a portion of which is disposed proximate to an exit of the compressor and interposed between the compressor and the combustor and the transition zone; and

a controller coupled to the system of the valves and configured to open and close individual ones of the valves for at least one of increasing and decreasing relative amounts of the air supplied to the first and second interiors.

3. The gas turbine engine according to claim 1 , wherein the control system controls the relative amounts of the air supplied to the first and second interiors in accordance with a pre-selected fuel to air ratio.

4. The gas turbine engine according to claim 1 , wherein the control system controls the relative amounts of the air supplied to the first and second interiors in accordance with current environmental conditions within the combustor, the compressor, the transition zone and the turbine.

5. A gas turbine engine including a combustor having a first interior in which a first fuel supplied thereto by a fuel circuit is combustible and a turbine, including rotating turbine blades, into which products of at least the combustion of the first fuel are receivable to power the rotation of the turbine blades, the gas turbine engine comprising:

a transition zone, including a second interior in which a second fuel supplied thereto by the fuel circuit and the products of the combustion of the first fuel are combustible, the transition zone being disposed to fluidly couple the combustor and the turbine to one another;

a plurality of fuel injectors, which are structurally supported by the transition zone and coupled to the fuel circuit, and which are configured to supply the second fuel to the second interior in any one of a single axial stage, multiple axial stages, a single axial circumferential stage and multiple axial circumferential stages;

a compressor, fluidly coupled to the combustor and the transition zone, by which air is supplied to the first and second interiors for the combustion therein; and

a control system coupled to the fuel circuit and configured to control relative amounts of the air to the first and second interiors and relative amounts of the first and second fuels supplied by the fuel circuit to the first and second interiors.

6. A method of operating a gas turbine engine in which a turbine is fluidly coupled to a combustor by a transition zone interposed therebetween and in which a compressor supplies air to the combustor and the transition zone, the method comprising:

supplying a first fuel to a first interior within the combustor;

combusting the first fuel in the first interior within the combustor;

supplying a second fuel to a second interior within the transition zone in any one of a single axial stage, multiple axial stages, a single axial circumferential stage and multiple axial circumferential stages;

combusting the second fuel and a stream of combustion products, received from the first interior, in the second interior within the transition zone; and

controlling relative amounts of the air and the first and second fuels supplied to the first and second interiors.

7. The method according to claim 6 , wherein the controlling is achieved in accordance with a pre-selected fuel to air ratio.

8. The method according to claim 6 , wherein the controlling is achieved in accordance with current environmental conditions within the combustor, the compressor, the transition zone and the turbine.