System and method for flame blow-off determination

1. A method for determining flame blow-off conditions for a fuel-oxidant mixture in a combustor, comprising:

selecting a plurality of cells from a region within said combustor;

obtaining a plurality of Damköhler numbers in accordance with detailed combustion chemistry and detailed flow dynamics associated with each of said plurality of cells;

providing an output representation associated with said Damköhler numbers; and

determining flame blow-off conditions in accordance with said output representation,

wherein each of said Damköhler numbers is obtained by dividing a chemical time by a residence time associated with each cell,

wherein said residence time is selected in accordance with at least one of a mean flow residence-time value or a turbulent flow residence timescale value associated with a cell, and

wherein said residence time is selected to be the minimum of said mean flow residence-time value and said turbulent flow timescale value.

2. The method of claim 1 , wherein one or more of said cells is selected in accordance with a sampling method.

3. The method of claim 1 , wherein the maximum number of cells to be considered is a user defined parameter.

4. The method of claim 1 , wherein at least one of said cells is selected from at least one of a flame and a pre-flame zones within said combustor.

5. The method of claim 4 , said flame and pre-flame zones are defined by a user.

6. The method of claim 4 , said flame and pre-flame zones are determined in accordance with computational fluid dynamics (CFD) computations.

7. The method of claim 1 , wherein said mean flow residence-time value is obtained by (1) dividing volume of said cell by cross-flow area associated with said cell, then (2) dividing the resulting value by the magnitude of mean flow velocity of the mixture.

8. The method of claim 1 , wherein said turbulent flow residence timescale value is obtained in accordance with turbulence kinetic energy and dissipation function associated with said cell.

9. The method of claim 1 , wherein said determining is carried out in accordance with a critical Damköhler number.

10. The method of claim 9 , wherein said critical Damköhler number is one.

11. The method of claim 9 , wherein said critical Damköhler number is a user-defined value.

12. The method of claim 1 , wherein said output representation comprises a contour of Damköhler numbers associated with each cell.

13. The method of claim 1 , wherein said output representation comprises cells with Damköhler numbers that are greater than a critical Damköhler number.

14. The method of claim 1 , wherein said output representation comprises a likelihood measure associated with producing flame blow-off with cell-level granularity.

15. The method of claim 1 , wherein said output representation comprises residence and chemical times.

16. The method of claim 1 , wherein said output representation is used to assess flame stability within said region.

17. A method for determining flame blow-off conditions for a fuel-oxidant mixture in a combustor, comprising:

selecting a plurality of cells from a region within said combustor;

obtaining a plurality of Damköhler numbers in accordance with detailed combustion chemistry and detailed flow dynamics associated with each of said plurality of cells;

providing an output representation associated with said Damköhler numbers; and

determining flame blow-off conditions in accordance with said output representation,

wherein each of said Damköhler numbers is obtained by dividing a chemical time by a residence time associated with each cell, and

wherein said chemical time is obtained by dividing a change in sensible enthalpy by a heat release rate associated with said cell.

18. The method of claim 17 , wherein one or more of said cells is selected in accordance with a sampling method.

19. The method of claim 17 , wherein at least one of said cells is selected from at least one of a flame and a pre-flame zones within said combustor.

20. The method of claim 17 , wherein said residence time is selected in accordance with at least one of a mean flow residence-time value or a turbulent flow residence timescale value associated with a cell, and wherein said mean flow residence-time value is obtained by (1) dividing volume of said cell by cross-flow area associated with said cell, then (2) dividing the resulting value by the magnitude of mean flow velocity of the mixture.

21. The method of claim 17 , wherein said residence time is selected in accordance with at least one of a mean flow residence-time value or a turbulent flow residence timescale value associated with a cell, and wherein said turbulent flow residence timescale value is obtained in accordance with turbulence kinetic energy and dissipation function associated with said cell.

22. The method of claim 17 , wherein said determining is carried out in accordance with a critical Damköhler number.

23. The method of claim 22 , wherein said critical Damköhler number is one.

24. The method of claim 17 , wherein said output representation comprises a contour of Damköhler numbers associated with each cell.

25. The method of claim 17 , wherein said output representation comprises cells with Damköhler numbers that are greater than a critical Damköhler number.

26. The method of claim 17 , wherein said output representation comprises a likelihood measure associated with producing flame blow-off with cell-level granularity.

27. The method of claim 17 , wherein said output representation comprises residence and chemical times.

28. The method of claim 17 , wherein said output representation is used to assess flame stability within said region.

29. A computer program product embodied on a non-transitory, non-transmissible computer-readable medium, configured to command one or more data processors to execute steps comprising:

selecting a plurality of cells from a region within a combustor;

obtaining a plurality of Damköhler numbers in accordance with detailed combustion chemistry and detailed flow dynamics associated with each of said plurality of cells;

providing an output representation associated with said Damköhler numbers; and

determining flame blow-off conditions in accordance with said output representation,

wherein each of said Damköhler numbers is obtained by dividing a chemical time by a residence time associated with each cell,

wherein said residence time is selected in accordance with at least one of a mean flow residence-time value or a turbulent flow residence timescale value associated with a cell, and

wherein said residence time is selected to be the minimum of said mean flow residence-time value and said turbulent flow timescale value.

30. The computer program product of claim 29 , wherein at least one of said cells is selected from at least one of a flame and a pre-flame zones within said combustor.

31. The computer program product of claim 29 , wherein said mean flow residence-time value is obtained by (1) dividing volume of said cell by cross-flow area associated with said cell, then (2) dividing the resulting value by the magnitude of mean flow velocity of the mixture.

32. The computer program product of claim 29 , wherein said turbulent flow residence timescale value is obtained in accordance with turbulence kinetic energy and dissipation function associated with said cell.

33. The computer program product of claim 29 , wherein said determining is carried out in accordance with a critical Damköhler number.

34. The computer program product of claim 29 , wherein said output representation comprises a likelihood measure associated with producing flame blow-off with cell-level granularity.

35. The computer program product of claim 29 , wherein said output representation comprises residence and chemical times.

36. A computer program product embodied on a non-transitory, non-transmissible computer-readable medium configured to command one or more data processors to execute steps, comprising:

selecting a plurality of cells from a region within a combustor;

obtaining a plurality of Damköhler numbers in accordance with detailed combustion chemistry and detailed flow dynamics associated with each of said plurality of cells;

providing an output representation associated with said Damköhler numbers; and

determining flame blow-off conditions in accordance with said output representation,

wherein each of said Damköhler numbers is obtained by dividing a chemical time by a residence time associated with each cell, and

wherein said chemical time is obtained by dividing a change in sensible enthalpy by a heat release rate associated with said cell.

37. The computer program product of claim 36 , wherein at least one of said cells is selected from at least one of a flame and a pre-flame zones within said combustor.

38. The computer program product of claim 36 , wherein said residence time is selected in accordance with at least one of a mean flow residence-time value or a turbulent flow residence timescale value associated with a cell, and wherein said mean flow residence-time value is obtained by (1) dividing volume of said cell by cross-flow area associated with said cell, then (2) dividing the resulting value by the magnitude of mean flow velocity of the mixture.

39. The computer program product of claim 36 , wherein said residence time is selected in accordance with at least one of a mean flow residence-time value or a turbulent flow residence timescale value associated with a cell, and wherein said turbulent flow residence timescale value is obtained in accordance with turbulence kinetic energy and dissipation function associated with said cell.

40. The computer program product of claim 36 , wherein said determining is carried out in accordance with a critical Damköhler number.

41. The computer program product of claim 36 , wherein said output representation comprises a likelihood measure associated with producing flame blow-off with cell-level granularity.

42. The computer program product of claim 36 , wherein said output representation comprises residence and chemical times.