Initial fire spread is composed of the processes of ignition, flame spread, and burning rate. The effects of a material's thermal characteristics and burning behaviors on flame spread are important. However, many zone and field models of compartment fire can not predict spread on objects accurately enough due to the neglect of these behaviors in their fire growth sub-models. As a result, a model dedicated to the early stage of fire growth is needed to provide the accuracy necessary for competent assessment of the response of safety systems, as well as satisfying the requirement for a comprehensive risk assessment. This study is undertaken to investigate the use of formulations outlined by previous researchers by review of the theory of flame spread models. A computer model is proposed that can determine the impact of the material properties with emphasis on practical engineering analyses. Through this computer program, we can obtain the pyrolysis zone, the flame height, the burnout time, the burnout portion, the mass loss rate, total heat release rate, and mean flame velocity of a material at specific time. The effort in this study has been focused on developing a relatively simple model for fire spread on a vertically oriented material which contains the most common aspect of fire growth theory such as the transit burning rate, material properties, burner affection, flame spread rate and burnout. This study used Vc++ as a program development platform which has an easy to use interface and reasonable execution times. The model is a combination of two sub-models. One is to simulate the flame spread on horizontal surface. The other is to simulate it on a vertical surface. In two sub-models, the spread process model is two-dimensioned yet symmetric. By using empirical physical equations and correlations, this model predicted flame spread by solving a set of closed coupled correlations simultaneously. Each sub-model contains several functions: ignition, mass loss rate calculation, burning area and the surface temperature calculation. The results of this proposed computer model are compared with experimental studies involving a limited number of comparisons of experimental data for early stage vertical flame spread. The model calculations and experimental measurements of the mass loss rate, heat release rate, and radiation flux were found to be in good agreement. Recommendations are made for further development of the more complex initial stage fire growth model.
| Identifer | oai:union.ndltd.org:ADTP/258450 |
| Date | January 2008 |
| Creators | Shi, Yan, Safety Science, Faculty of Science, UNSW |
| Publisher | Publisher:University of New South Wales. Safety Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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