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Simulating Fire Dynamics and the Thermal Response of Structural Elements

Published

Author(s)

Kuldeep R. Prasad, Howard R. Baum

Abstract

Simulations of the effects of severe fires on the structural integrity of building requires a close coupling between the gas phase energy release and transport phenomena and the stress analysis in the load bearing materials. The connection between the two is established primarily through the interaction of the radiation heat transfer between the solid and gas phases with the conduction of heat through the structural elements. These processes occur on very different length and time scales. As a result, the computer codes used to implement solutions of these equations have little in common. The overall goal of this project is to develop the ability to couple the NIST Fire Dynamics Simulator directly to a suitable thermal / structural analysis code. However, as a first step, we present a simple model for computing the radiative heat transfer to structural elements. This model assumes that the compartment is divided into a hot, soot laden upper layer and a cool relatively clear lower layer. The temperature in each layer is taken to be spatially uniform, but not necessarily equal to the temperatures of the floor and ceiling. For such a geometry, the radiative transport equation can be solved exactly and explicit formulae for the heat flux are obtained as a function of temperatures, hot layer depth, soot concentration and orientation of the structural element. These formulae are used to generate realistic thermal boundary conditions for a coupled transient three-dimensional finite element code. The paper will describe the formulation of the model and its application to coupling the gas phase fire dynamics simulation to the solid phase thermal / stress analysis of the structural elements.
Citation
Joint Meeting of the Combustion Institute

Keywords

Fire Dynamics

Citation

Prasad, K. and Baum, H. (2003), Simulating Fire Dynamics and the Thermal Response of Structural Elements, Joint Meeting of the Combustion Institute (Accessed May 20, 2022)
Created March 19, 2003, Updated June 2, 2021