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Algorithm to Describe the Spread of a Wall Fire Under a Ceiling.


pdf icon Algorithm to Describe the Spread of a Wall Fire Under a Ceiling. (1979 K)
Mitler, H. E.

NISTIR 5547; 53 p. November 1994.

Available from:

National Technical Information Service
Order number: PB95-182259

Keywords:

algorithms; ceilings; ceiling fires; computer models; fire growth; fire spread; pyrolysis rate; wall fires

Abstract:

After some discussion of wall fires, the effects that a ceiling has on a wall fire are analyzed and discussed qualitatively. There are two kinds of effects: first, when the upper sill of the ventilating opening lies below the ceiling (as is usual), a layer of hot gas is trapped, which heats the walls by convection and radiation; the heated ceiling also radiates to the walls. A calculation which uses the wall-fire computer model SPREAD is carried out to demonstrate how these effects can be calculated now. Second, when the flame impinges on the ceiling, it bifurcates and spreads horizontally, rather than vertically. A simple algorithm is presented which calculates the spread rate of these horizontal flame extensions, as well as the modified pyrolysis rate, due to the modified radiation feedbacks.