Physical and Chemical Aspects of Cup-Burner Flame Extinguishment.
Physical and Chemical Aspects of Cup-Burner Flame
Extinguishment.
(347 K)
Takahashi, F.; Linteris, G. T.; Katta, V. R.
Paper 21; HOTWC 2005;
Halon Options Technical Working Conference, 15th
Proceedings. HOTWC 2005. Sponsored by: 3M Specialty
Materials, Boeing, Chemical Development Studies, Inc.,
DuPont Fire Extinguishants, Halon Alternative Research
Corp., Hughes Associates, Inc., Kidde-Fenwal, Inc.,
Sandia National Laboratories, SEVO Systems, Next
Generation Fire Suppression Technology Program. May
24-26, 2005, Albuquerque, NM, 1-10 pp, 2005.
Keywords:
halon alternatives; halons; halon 1301; cup burners;
flame extinguishment; diffusion flames; laminar flames;
fire extinguishing agents; heat capacity; flame
temperature; flame structure
Abstract:
Extinguishing limits of laminar methane-air co-flow
diffusion flames in a cup-burner apparatus in normal
earth gravity have been determined experimentally and
computationally. A gaseous fire-extinguishing agent (Ar,
He, N2, CO2, CF3H, CF3Br, or Br2) was added gradually
into the coflowing oxidizer until the flame
extinguished. The extinguishment of cup-burner flames,
which resemble real fires, occurred via a blowoff
process (in which the flame base oscillated before
drifted downstream eventually) rather than the global
extinction typical of counterflow diffusion flames.
Unsteady numerical simulations with detailed chemistry
revealed that the peak reactivity spot (i.e., reaction
kernel), formed at the flame attachment point, was
responsible for blowoff-type flame extinguishment. The
complexity of chemical kinetics and dynamic flame-flow
interactions associated with the blowoff process were
treated accurately in the numerical model and the
predictions for minimum extinguishing concentrations of
various agents were in good agreement with the
measurements.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899