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Calculating Flame Spread on Horizontal and Vertical Surfaces.


pdf icon Calculating Flame Spread on Horizontal and Vertical Surfaces. (2408 K)
Ahmed, G. N.; Dietenberger, M. A.; Jones, W. W.

NISTIR 5392; 56 p. April 1994.

Available from:

National Technical Information Service
Order number: PB94-187283

Keywords:

flame spread; computer algorithms; fire models; zone models; test methods; lateral ignition

Abstract:

The flame spread model described in this paper is a new algorithm which provdes the capability to calculate a self-consistent fire based substantually on bench scale fire data. The flame spread model simulates object fire growth and burnout of a slab in a room and produces acceptable predictions of the spread of fire, smoke and production of both toxic and nontoxic gases. The purpose of the flame spread model is to allow a fire to grow realistically, possibly making a hole in the material surface. This is one mechanism for barrier penetration. The algorithm is based on empirical data, gathered from standard test apparatus, including the Cone Calorimeter and the LIFT (lateral ignition flame spread test method). By basing the pyrolysis on test methods, we avoid the practical difficulties associated with an explicit calculation of radiation blocking and material charring. The objective of including the flame spread model is to predict the accelerative growth of a fire from ignition to a peak value and then the gradual termination normally seen in a fire. The intent of the project was to develop an algorithm which could be utilized in a complete model of a fire in a building. The three-dimensional aspects of the flame spread model include: first, panels made of combustible materials with different thicknesses and at various orientations; second, flames of two basic types, pool fire and purely wall fire; third, a radiation heat exchange between objects, flames, and gases. The pool fire has a flame spreading polygon on a horizontal panel and the wall fire is used either for inclined or vertical panels.