Utilizing a diluent to lower combustion instabilities in a gas turbine engine

1. A method of influencing combustion dynamics, comprising:

measuring pressure oscillations within a combustor; and

controlling a non-fuel diluent flow that is delivered only to a fuel flow upstream of a pilot burner fuel outlet in response to the measured pressure oscillations,

wherein the controlling occurs independent of control of a flow of fuel to an associated premix main burner,

wherein the associated premix main burner is one of a plurality of premix main burners disposed in an annular array surrounding the pilot burner, and

wherein the plurality of premix main burners and the pilot burner are disposed within the combustor and are effective to create a single combustion flame comprising a pilot flame formed by the pilot burner.

2. The method of claim 1 , wherein the pilot burner is a diffusion pilot burner.

3. The method of claim 1 , wherein the fuel flow and diluent flow form a diluted flow and the diluted flow rate is greater than a fuel flow rate when the diluent is added.

4. The method of claim 3 , wherein the fuel flow rate is not reduced when the diluent is added.

5. The method of claim 1 , wherein a fuel flow rate is not changed.

6. The method of claim 1 , further comprising controlling diluent flow to prevent clogging of the pilot burner fuel outlet.

7. The method of claim 1 , wherein the diluent is in gas form.

8. The method of claim 1 , wherein the diluent is inert.

9. The method of claim 1 , wherein the diluent is nitrogen.

10. The method of claim 1 , wherein the non-fuel diluent is characterized by a different phase than the fuel.

11. A method of influencing combustion dynamics in a gas turbine engine, comprising:

monitoring a combustor for a combustion dynamics parameter associated with pressure oscillations; and

adjusting a pilot flame parameter in response to the combustion dynamics parameter by controlling a non-fuel diluent flow into a fuel flow and delivering a combined flow only to a pilot flame through a pilot burner fuel outlet, wherein the controlling of the non-fuel diluent flow occurs independent of control of a flow of fuel to an associated premix main burner,

wherein the associated premix main burner is one of a plurality of premix main burners disposed in an annular array surrounding the pilot burner, and

wherein the plurality of premix main burners and the pilot burner are disposed within the combustor and are effective to create a single combustion flame comprising a pilot flame formed by the pilot burner.

12. The method of claim 11 , wherein the pilot burner is a diffusion pilot burner.

13. The method of claim 11 , wherein a combined flow rate is greater than a fuel flow rate.

14. The method of claim 11 , wherein a fuel flow rate is not adjusted when the diluent flow is added.

15. The method of claim 11 , wherein a fuel flow rate is not adjusted.

16. The method of claim 11 , further comprising controlling the diluent to prevent clogging of the pilot burner fuel outlet.

17. The method of claim 11 , wherein the diluent is inert.

18. The method of claim 11 , wherein the diluent is nitrogen.

19. A method of influencing combustion dynamics in a combustor of a gas turbine engine, the combustor including premix main burners disposed in an annular array around a diffusion pilot burner, the method comprising:

monitoring a pressure-oscillation related combustion dynamics parameter, and

controlling a flow of a diluent delivered to a fuel flow dedicated to a pilot burner but not to a fuel flow dedicated to the premix main burners in response to the combustion dynamics parameter,

wherein the controlling occurs independent of control of a flow of fuel to the premix main burners and a control of a flow of fuel to the pilot burner,

wherein the diluent contributes no energy to a pilot flame associated with the pilot burner, and

wherein the premix main burners are disposed in an annular array surrounding the pilot burner and are effective to create a single combustion flame comprising a pilot flame formed by the pilot burner.