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Application of CFD Modeling to Room Fire Growth on Walls.


pdf icon Application of CFD Modeling to Room Fire Growth on Walls. (1494 K)
Liang, K. M.; Ma, T.; Quintiere, J. G.; Rouson, D.

NIST GCR 03-849; 86 p. April 2003.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Available from:

: National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161.
Telephone: 1-800-553-6847 or 703-605-6000;
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Keywords:

computational fluid dynamics; room fires; walls; fire growth; fire plumes; flame spread; burning rate; computer programs; compartment fires

Abstract:

An evaluation of the NIST FDS model was conducted with particular attention for its use in predicting flame spread on surfaces. Over the course of this investigation the computational model changed from combustion depicted by particles to a mixture fraction based combustion model. The study pertains to version 2.0 released on December 4, 2001. Three aspects were considered in the study. First, we studied the evaluation of the code to predict a combusting plume. Second, the code was applied to a fire plume adjacent to a vertical wall, and then flame spread on the wall. Third, a complementary investigation of an improved algorithm for convective heat transfer at a surface was developed. The first two studies resulted in M.S. theses. Damian Rouson of CCNY performed the third study. The thesis by Ma on the axi-symmetric plume was previously transmitted and will not be included here. However, a recently accepted paper, based on the thesis with updated results is included. The general conclusions are that the FDS code is very good for computing the fluid dynamics, entrainment and flame height. The temperature in the combustion region appears to be over-estimated at the base of the geometry considered, and any related heat flux is consequently over-predicted. The temperature results are grid dependent. A computation of flame spread on vertical PMMA gave mixed results. The code was benchmarked against fire plume correlations after a review of the literature to obtain the most general results. Most of the experimental correlations have some deficiencies, and should be improved. Particular attention needs to be given to temperature measurements in the flame since these are generally under-estimated due to radiation error. The wall heat flux and flame spread comparisons were made against data we viewed as quality data. The algorithm developed by Rouson is based on the theoretical formulation by Howard Baum, and has not been tested in the FDS code.