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Further Studies of Cup-Burner Flame Extinguishment.


pdf icon Further Studies of Cup-Burner Flame Extinguishment. (516 K)
Takahashi, F.; Linteris, G. T.; Katta, V. R.

HOTWC 2006;

Halon Options Technical Working Conference, 16th Proceedings. HOTWC 2006. May 16-18, 2006, Albuquerque, NM, 1-13 pp, 2006.

Keywords:

halon alternatives; halons; halon 1301; fire suppression; flame extinguishment; diffusion flames; gravity; fire extinguishing agents; flame structures; heptane; burners; carbon dioxide; reaction kinetics

Abstract:

The structure and extinguishment of heptane-air co-flow diffusion flames formed on a cup burner in normal earth gravity have been studied experimentally and computationally. A gaseous fire-extinguishing agent (CO2) was introduced gradually into a coflowing oxidizer stream until blowoff-type extinguishment occurred. The measured minimum extinguishing concentration of CO2 was (19.2 - 0.8) % in volume fraction. A first attempt was made at numerical simulations with full n-heptane chemistry to reveal the detailed flame structure and suppression processes. Overall features of n-heptane flames resembled those of methane flames studied previously: a peak reactivity spot (reaction kernel) in the flame base was responsible for flame attachment and destabilization processes. The initial fuel (heptane) decomposed at moderate temperatures and disappeared on the fuel side before reaching the high-temperature flame zone, and thus CO, H2, C2H2, CH4, and C2H4 became the major intermediates and fuel fragments burning in the flame zone.