Extinction Conditions of Non-Premixed Flames with Fine Droplets of Water and Water/NaOH Solutions
VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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Interactions of fine droplets of water and waterNaOH solutions with a steady, laminar counterflow methaneair non-premixed flame are investigated experimentally and numerically. A water atomizer generating a polydisperse distribution of droplet sizes with a median diameter of 20 micrometers 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 micrometers monodisperse water droplets. The hybrid Eulerian-Lagrangian numerical model previously developed is generalized to include polydisperse distribution of drop sizes however, the differences seen between experiments and the numerical predictions at high water mass fractions could not be attributed to variation in 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 17.5 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.
- Numerical Mathematics
- Combustion and Ignition
- Fluid Mechanics