Method of using a primary fuel to pilot liquid fueled combustors

1. A fuel delivery system for a combustor of a gas turbine engine, the fuel delivery system comprising:

a primary fuel tank configured to store a primary fuel;

a secondary fuel tank configured to store a secondary fuel;

a swirler configured to produce a main flame within a combustion chamber of the combustor;

a fuel nozzle configured to produce a pilot flame within the combustion chamber of the combustor, wherein the fuel nozzle comprises a nozzle outlet that is located adjacent to an end of the swirler or at the end of the swirler such that combustion of the primary fuel to produce the pilot flame occurs outside of the swirler, the end of the swirler being located at an inlet of the combustor, wherein the end of the swirler is an axially aftmost end of the swirler with respect to a centerline of the combustion chamber, the fuel nozzle outlet is axially inline with a surface of an end wall of the end of the swirler, wherein the surface of the end wall extends along a radial direction with respect to the centerline;

a primary fuel line fluidly connecting the primary fuel tank to the fuel nozzle;

a secondary fuel line fluidly connecting the secondary fuel tank to the swirler, wherein the secondary fuel does not mix with the primary fuel until the secondary fuel has exited the swirler;

a secondary fuel pilot line fluidly connecting the secondary fuel tank to the fuel nozzle; and

a pilot fuel selection valve located within the primary fuel line and the secondary fuel pilot line, the pilot fuel selection valve being configured to be actuated to one or more positions to adjust a flow to the fuel nozzle of at least one of the primary fuel and the secondary fuel.

2. The fuel delivery system of claim 1 , further comprising:

a combined pilot fuel line fluidly connecting the pilot fuel selection valve to the fuel nozzle, wherein the primary fuel line and the secondary fuel pilot line are combined into the combined pilot fuel line between the pilot fuel selection valve and the fuel nozzle.

3. The fuel delivery system of claim 1 , wherein the fuel delivery system is a passive system and configured to adjust the position of the pilot fuel selection valve based upon a schedule of operating conditions.

4. The fuel delivery system of claim 1 , further comprising:

a logic controller including one or more sensors configured to detect operation conditions of the gas turbine engine, the logic controller being in electronic communication with the pilot fuel selection valve,

wherein the fuel delivery system is an active feedback system and configured to adjust the position of the pilot fuel selection valve based upon a detection of operating conditions using the logic controller.

5. The fuel delivery system of claim 1 , further comprising:

a secondary fuel control valve located within the secondary fuel pilot line between the second fuel secondary fuel tank and the pilot fuel selection valve, the secondary fuel control valve being configured to be actuated to one or more positions to adjust the flow of the secondary fuel to the pilot fuel selection valve.

6. The fuel delivery system of claim 5 , further comprising:

a combined pilot fuel line fluidly connecting the pilot fuel selection valve to the fuel nozzle, wherein the primary fuel line and the secondary fuel pilot line are combined into the combined pilot fuel line between the pilot fuel selection valve and the fuel nozzle.

7. The fuel delivery system of claim 5 , wherein the fuel delivery system is a passive system and configured to adjust the position of the pilot fuel selection valve based upon a schedule of operating conditions.

8. The fuel delivery system of claim 5 , further comprising:

a logic controller including one or more sensors configured to detect operation conditions of the gas turbine engine, the logic controller being in electronic communication with the pilot fuel selection valve,

wherein the fuel delivery system is an active feedback system and configured to adjust the position of the pilot fuel selection valve based upon a detection of operating conditions using the logic controller.

9. The fuel delivery system of claim 8 , wherein the logic controller is in electronic communication with the secondary fuel control valve and configured to adjust the position of the secondary fuel control valve based upon a detection of operating conditions.

10. The fuel delivery system of claim 1 , the primary fuel is hydrogen.

11. A method of delivering fuel to a combustor of a gas turbine engine, the method comprising:

storing a primary fuel in a primary fuel tank of a fuel delivery system;

storing a secondary fuel in a secondary fuel tank;

producing, using a swirler, a main flame within a combustion chamber of the combustor;

producing, using a fuel nozzle, a pilot flame within the combustion chamber of the combustor, wherein the fuel nozzle comprises a nozzle outlet that is located adjacent to an end of the swirler or at the end of the swirler such that combustion of the primary fuel to produce the pilot flame occurs outside of the swirler, the end of the swirler being located at an inlet of the combustor, wherein the end of the swirler is an axially aftmost end of the swirler with respect to a centerline of the combustion chamber, the fuel nozzle outlet is axially inline with a surface of an end wall of the end of the swirler, wherein the surface of the end wall extends along a radial direction with respect to the centerline;

conveying, using a primary fuel line, the primary fuel from the primary fuel tank to the fuel nozzle;

conveying, using a secondary fuel line, the secondary fuel from the secondary fuel tank to the swirler, wherein the secondary fuel does not mix with the primary fuel until the secondary fuel has exited the swirler;

conveying, using a secondary fuel pilot line, the secondary fuel from the secondary fuel tank to the fuel nozzle; and

adjusting, using a pilot fuel selection valve, a flow to the fuel nozzle of at least one of the primary fuel and the secondary fuel.

12. The method of claim 11 , further comprising:

conveying, using a combined pilot fuel line, at least one of the primary fuel and the secondary fuel from the pilot fuel selection valve to the fuel nozzle, wherein the primary fuel line and the secondary fuel pilot line are combined into the combined pilot fuel line between the pilot fuel selection valve and the fuel nozzle.

13. The method of claim 11 , further comprising:

adjusting a position of the pilot fuel selection valve based upon a schedule of operating conditions, wherein the fuel delivery system is a passive system.

14. The method of claim 11 , further comprising:

adjusting, using a logic controller, a position of the pilot fuel selection valve based upon detection of operating conditions, the logic controller including one or more sensors configured to detect operation conditions of the gas turbine engine.

15. The method of claim 11 , further comprising:

adjusting, using a secondary fuel control valve, a flow of the secondary fuel between the second fuel secondary fuel tank and the pilot fuel selection valve.

16. The method of claim 15 , further comprising:

conveying, using a combined pilot fuel line, at least one of the primary fuel and the secondary fuel from the pilot fuel selection valve to the fuel nozzle, wherein the primary fuel line and the secondary fuel pilot line are combined into the combined pilot fuel line between the pilot fuel selection valve and the fuel nozzle.

17. The method of claim 15 , further comprising:

adjusting a position of the pilot fuel selection valve based upon a schedule of operating conditions.

18. The method of claim 15 , further comprising:

adjusting, using a logic controller, a position of the pilot fuel selection valve based upon detection of operating conditions, the logic controller including one or more sensors configured to detect operation conditions of the gas turbine engine.

19. The method of claim 18 , further comprising:

adjusting, using the logic controller, a position of the secondary fuel control valve based upon detection of operating conditions, the one or more sensors configured to detect operation conditions of the gas turbine engine.

20. The method of claim 11 , wherein the primary fuel is hydrogen.