- Author
- Fernandez-Pello, A. C.
- Title
- Fire Propagation in Concurrent Flows. Final Progress Report. June 1, 1984-May 31, 1985.
- Coporate
- California Univ., Berkeley
- Sponsor
- National Bureau of Standards, Gaithersburg, MD
- Report
- NBS GCR 86-505, February 1986, 49 p.
- Distribution
- Available from National Technical Information Service
- Contract
- NBS-GRANT-NB83NADA4020
- Keywords
- flame extinguishment | flame research | flame spread | heat transfer | oxygen concentration | oxygen index
- Abstract
- A study is currently underway of the spread of flames over the surface of a solid combustion of a solid combustible in a mixed, forced and free, convective flow. Research efforts have concentrated primarily on a experimental study of the flow assisted spread of flames over thermally thin fuels, and a numerical analysis of the extinction of flames established over a flat combustible surface. The experimental results indicate that wind aided fire spread is primarily controlled by heat transfer from the flame to the unburnt combustible. The flame spread rate data can be correlated with and expression obtained from a heat transfer analysis of the flame spread process. The experiments also showed that extinction of the flames, due to vitiated (low oxygen concentration) or high velocity conditions, occurs at the upstream leading edge of the flame. A numerical analysis of the flame extinction process has also been completed. It is predicted that the flame positions itself along the viscous layer such that the chemical and residence times are of the same order of magnitude, and that total extinction occurs at oxygen concentrations of approximately 0.18. This agrees with previous measurements of the limiting oxygen index from PMMA.