The lean blowout stability of a non-premixed, V-gutter stabilized flame was investigated using a Damkohler number methodology. The flow and chemical timescales were extracted from the reacting RANS CFD results on a cell-by-cell basis. Assessment of three representative definitions of flow and chemical timescales for Damkohler number based on different blowout mechanisms was performed. By examining the Damkohler number fields, the structure of the flame or the possibility of blowout can be estimated. The results demonstrated that a distinct transition between stable and unstable flames was observed by decreasing the fuel-air ratio or increasing the inlet velocity at atmosphere pressure and an inlet temperature of 537K. All three definitions can predict the lean blowout limit in a reasonable consistent with the available experimental data through adjusting the critical Damkohler number of each definition in the current study. The performances and physical differences of three definitions were also discussed.

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