This study investigates the relationship between the flame transition and the diluted percentage of nitrogen in the methane/nitrogen mixture. Both numerical and experimental works find that in the regimeYCH 4 ≤ 0.6, the envelope flame will transform into wake one directly when incoming velocity gradually increases to a limiting value. On the other hand, in the regime of YCH4 > 0.6,the lift-off flame, which is only survived for a moment in the experiment, or extinction will appear between the envelop and wake ones as the velocity increases. From the numerical results, it is identified that the envelope flame is a pure diffusion one, whereas the wake flame shows the characteristics of a premixed flame in the reaction front region. As to the lift-off flame, this study finds that the fuel and oxidizer is incompletely mixed and it lacks a recirculation flow to re-ignite the flammable mixture, leading to extinction. Besides, this study also finds that the flame transition limit is reduced as the mass fraction of methane in fuel mixture is lowered. The predicted trend is similar to the one observed experimentally.
|Number of pages||4|
|State||Published - 1 Dec 2005|
|Event||5th Asia-Pacific Conference on Combustion, ASPACC 2005 - Adelaide, SA, Australia|
Duration: 17 Jul 2005 → 20 Jul 2005
|Conference||5th Asia-Pacific Conference on Combustion, ASPACC 2005|
|Period||17/07/05 → 20/07/05|