Device for determining a fuel split, as gas turbine or an aircraft engine comprising such a device and application of the same

1. A device for determining a final fuel split between a pilot burner and a main burner of a staged combustion chamber of a gas turbine or aircraft engine, comprising:

a determining unit programmed to determine a preselected fuel split demand for the staged combustion chamber based on a detection as to whether the gas turbine or aircraft engine is in a steady state or a transient state and also based on at least one chosen from a combustion chamber exit temperature, a turbine input temperature, and a value for a fuel/air ratio;

wherein the determining unit is also programmed to:

determine a smoke limit fuel split demand based on a smoke limit,

select a respectively lower value of the preselected fuel split demand and the smoke limit fuel split demand as a first fuel split parameter, and

determine the final fuel split based on the first fuel split parameter;

output a final fuel split control signal to a final fuel split valve control device to control the supply of the final fuel split to the pilot burner and to the main burner.

2. The device according to claim 1 , wherein the determining unit is also programmed to:

distinguish the steady state from the transient state based on a temperature value in the staged combustion chamber that is representative of the final fuel split,

output a first control signal to a first control device for controlling the first control device to select between the steady state and the transient state.

3. The device according to claim 1 , wherein the determining unit is also programmed to:

select a respectively higher value of the first fuel split parameter and a fuel split demand which is representative of a weak extinction limit of a flame in the staged combustion chamber as a second fuel split parameter, and

output a signal to a second control device based on the second fuel split parameter.

4. The device according to claim 3 , wherein the determining unit is also programmed to:

determine a third fuel split parameter by selecting between the second fuel split parameter and a fuel split demand based on a backup control law, and

output a second control signal for controlling the second control device to select the third fuel split parameter.

5. The device according to claim 3 , wherein the fuel split demand which is representative of the weak extinction limit of the flame in the staged combustion chamber is representative of a lean flame extinction.

6. The device according to claim 1 , wherein the determining unit is also programmed to:

determine a fourth fuel split parameter based on at least one fuel split demand based on a turbine operating parameter indicating abnormal operating conditions, and

output a third control signal for controlling a third control device to select a fuel split based on the turbine operating parameter indicating abnormal operating conditions.

7. The device according to claim 6 , wherein the at least one turbine operating parameter indicating abnormal operating conditions includes conditions of at least one chosen from starting of the gas turbine or aircraft engine, re-ignition of the gas turbine or aircraft engine, water ingestion, compressor surge and extinction of a combustion flame within the staged combustion chamber.

8. The device according to claim 6 , wherein the determining unit is also programmed to:

determine a fifth fuel split parameter by selecting a respectively higher value of the fourth fuel split parameter and a fuel split demand for minimal fuel flow based on a total fuel flow; and

output a signal based on the fifth fuel split parameter.

9. The device according to claim 8 , wherein the determining unit is also programmed to:

determine a sixth fuel split parameter by selecting a respectively lowest value of the fifth fuel split parameter, a fuel split demand taking into account a prohibited range, and a fuel split demand for safeguarding against excess fuel pressure based on a fuel pressure in a fuel system of the pilot burner; and

output a signal based on the sixth fuel split parameter.

10. The device according to claim 9 , wherein the determining unit is also programmed to:

determine a fuel split demand for a fuel filling level of an injector based on the fuel filling level; and

output the final fuel split control signal by selecting between the sixth fuel split parameter and the fuel split demand for the fuel filling level of the injector, where a preset selection is the fuel split demand for the fuel filling level of the injector.

11. The device according to claim 1 , wherein the determining unit is also programmed to:

determine a fuel split demand taking into account a prohibited range based on parameters representative of a range of fuel flow ratios that cannot be set due to at least one chosen from hydrodynamic conditions and thermal boundary conditions; and

output a signal based on the fuel split demand taking into account the prohibited range.

12. The device according to claim 1 , wherein the determining unit is also programmed to determine the final fuel split based on at least one chosen from a weak extinction limit, a turbine operating parameter indicating abnormal operating conditions, a backup control law, a total fuel flow, a range of fuel ratios that cannot be set due to hydrodynamic or thermal boundary conditions, a fuel pressure in a fuel system of the pilot burner and a fuel filling level.

13. The device according to claim 1 , wherein the determining unit is also programmed to output the final fuel split control signal to control the final fuel split valve control device to control the supply of the final fuel split to the pilot burner and to the main burner such that pilot burner introduces a richer fuel mixture into the staged combustion chamber than the main burner.

14. An aircraft engine or gas turbine, comprising the device according to claim 1 .

15. A method for determining a final fuel split between a pilot burner and a main burner of a staged combustion chamber of a gas turbine or aircraft engine, comprising:

determining a preselected fuel split demand for the staged combustion chamber based on a detection as to whether the gas turbine or aircraft engine is in a steady state or a transient state and also based on at least one chosen from a combustion chamber exit temperature a turbine input temperature, and a value for a fuel/air ratio;

determining a smoke limit fuel split demand based on a smoke limit,

selecting a respectively lower value of the preselected fuel split demand and the smoke limit fuel split demand as a first fuel split parameter, and

determining the final fuel split based on the first fuel split parameter;

outputting a final fuel split control signal to a final fuel split valve control device to control the supply of the final fuel split to the pilot burner and to the main burner.

16. The method according to claim 15 , and further comprising:

distinguishing the steady state from the transient state based on a temperature value in the staged combustion chamber that is representative of the final fuel split,

outputting a first control signal to select between the steady state and the transient state.

17. The method according to claim 15 , and further comprising:

selecting a respectively higher value of the first fuel split parameter and a fuel split demand which is representative of a weak extinction limit of a flame in the staged combustion chamber as a second fuel split parameter, and

outputting a signal to a control device based on the second fuel split parameter.

18. The method according to claim 17 , and further comprising:

determining a third fuel split parameter by selecting between the second fuel split parameter and a fuel split demand based on a backup control law, and

outputting a second control signal to select the third fuel split parameter.

19. The method according to claim 17 , wherein the fuel split demand which is representative of the weak extinction limit of the flame in the staged combustion chamber is representative of a lean flame extinction.

20. The method according to claim 15 , and further comprising:

determining a fourth fuel split parameter based on at least one fuel split demand based on a turbine operating parameter indicating abnormal operating conditions, and

outputting a third control signal to select a fuel split based on the turbine operating parameter indicating abnormal operating conditions.

21. The method according to claim 20 , and further comprising providing that the at least one turbine operating parameter indicating abnormal operating conditions includes conditions of at least one chosen from starting of the gas turbine or aircraft engine, re-ignition of the gas turbine or aircraft engine, water ingestion, compressor surge and extinction of a combustion flame within the staged combustion chamber.

22. The method according to claim 20 , and further comprising:

determining a fifth fuel split parameter by selecting a respectively higher value of the fourth fuel split parameter and a fuel split demand for minimal fuel flow based on a total fuel flow: and

outputting a signal based on the fifth fuel split parameter.

23. The method according to claim 22 , and further comprising:

determining a sixth fuel split parameter by selecting a respectively lowest value of the fifth fuel split parameter, a fuel split demand taking into account a prohibited range, and a fuel split demand for safeguarding against excess fuel pressure based on a fuel pressure in a fuel system of the pilot burner; and

outputting a signal based on the sixth fuel split parameter.

24. The method according to claim 23 , and further comprising:

determining a fuel split demand for a fuel filling level of an injector based on the fuel filling level; and

outputting the final fuel split control signal by selecting between the sixth fuel split parameter and the fuel split demand for the fuel filling level of the injector, where a preset selection is the fuel split demand for the fuel filling level of the injector.

25. The method according to claim 15 , and further comprising:

determining a fuel split demand taking into account a prohibited range based on parameters representative of a range of fuel flow ratios that cannot be set due to at least one chosen from hydrodynamic conditions and thermal boundary conditions; and

outputting a signal based on the fuel split demand taking into account the prohibited range.

26. The method according to claim 15 , and further comprising determining the final fuel split based on at least one chosen from a weak extinction limit, a turbine operating parameter indicating abnormal operating conditions, a backup control law, a total fuel flow, a range of fuel ratios that cannot be set due to hydrodynamic or thermal boundary conditions, a fuel pressure in a fuel system of the pilot burner and a fuel filling level.

27. The method according to claim 15 , and further comprising outputting the final fuel split control signal to control the final fuel split valve control device to control the supply of the final fuel split to the pilot burner and to the main burner such that pilot burner introduces a richer fuel mixture into the staged combustion chamber than the main burner.