Extinction Conditions of Non-Premixed Flames With Fine Droplets of Water and Water-NaOH Solutions.
Extinction Conditions of Non-Premixed Flames With Fine
Droplets of Water and Water-NaOH Solutions.
Lazzarini, A. K.; Krauss, R. H.; Chelliah, H. K.;
Linteris, G. T.
Combustion Institute, Symposium (International) on
Combustion, 28th. Proceedings. Volume 2. July
20-August 4, 2000, Edinburgh, Scotland, Combustion
Institute, Pittsburgh, PA, Candel, S.; Driscoll, J. F.;
Burgess, A. R.; Gore, J. P., Editor(s)(s), 2939-2945 pp,
combustion; droplets; flame chemistry; water mist; halon
alternatives; flame suppression; sodium hydroxide;
extinction; premixed flames; burners; drop sizes; size
distribution; water vapors; mass flow; flow rate
Interactions of fine droplets of water and water-NaOH
solutions with a steady, laminar counterflow methane-air
flame are investigated, both experimentally and
numerically. A water atomizer generating a polydisperse
distribution of droplet sizes with a mean diameter of 20
m is used in experiments with steady feed rate.
Comparisons of the measured flame extinction condition
as a function of droplet mass fraction in the air stream
indicate a trend similar to that predicted previously
using 20 m mondisperse water droplets. The hybrid
Eulerian-Lagrangian numerical model previously developed
is generalized to include polydisperse distribution of
droplet sizes, however, the differences seen between
experiments and the numerical predictions at high water
mass fractions could not be attributed to variation is
size distribution alone. Present experiments support the
conclusions of an earlier modeling work that, on a mass
basis, fine water mist can be as effective as the now
banned gaseous fire suppressant halon 1301. Inclusion of
NaOH in water (up to 18% by mass), is shown to
significantly enhance the fire suppression ability of
water by complementing its thermal effects with chemical
catalytic radical recombination effects of NaOH.