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Title:Computational investigation of flahover mechanisms using fire dynamics simulator (fds)
Author(s):Lee, Sangkyoung
Advisor(s):Kyritsis, Dimitrios C.
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Fire Dynamics Simulator (FDS)
Ceiling Height
Abstract:A pilot study of the development of flashover in enclosure fires was performed using the Fire Dynamics Simulator (FDS) platform. Practical criteria for flashover commonly proposed in the literature were investigated in the context of FDS modeling to determine similarity between the CFD model, previous experiments and zone-modeling results. The primary focus of the thesis was to determine FDS-generated flashover criteria that are consistent with established guidelines and can be shown to be independent of the specific configuration of the compartment. As such, a parametric study was performed to calculate the time to flashover (TTF) and maximum heat release rate as a function of parameters that relate to compartment height and ventilation configuration. The computational domain used for this analysis was a 2.4 x 2.4 x 2.4 m3 cube with a seating chair, table and carpet with a ventilation opening centered in one wall. The results indicated that the FDS-generated flashover criteria of a radiative heat flux of 20kW/m2 at the floor level and average upper layer temperature of 600℃ were, in most cases appropriate regardless of ceiling height and the configuration of ventilation. However, the results suggest that a ceiling temperature of 600 °C is not a good general criterion for flashover. With increasing ceiling height, the TTF increased significantly, even for a series of models that maintained a uniform compartment volume as the ceiling height increased. This latter result suggests that the delay in flashover can be attributed to the change of heat flux from the upper hot gas layer as well as the additional filling volume from a raised ceiling height. Also, modifications in ventilation size and dimension had noticeable effects on the time to flashover and maximum heat release.
Issue Date:2011-05-25
Rights Information:Copyright 2011 Sangkyoung Lee
Date Available in IDEALS:2011-05-25
Date Deposited:2011-05

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