Further Studies of Cup-Burner Flame Extinguishment.
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899