Modelling the spread of a straight fire front through a horizontalporous fuel bed without wind

摘要

A semi-empirical model for a steady linear fire front propagating through a statisticallyrnhomogeneous solid porous bed, for the basic case of no wind, no slope and fine fuel particles,rnis presented. The model’s structure is modular, laying on a library of sub models for thernrelevant heat sink, heat flux and heat source phenomena. The sub modeling of moisture heat absorptionrnand radiation heat fluxes is particularly careful. At present, the model is not closed, requiringrnthe effective radiant temperature of the lower part of the fire front and the combustionrnmass efficiency, as inputs. A laboratory fire test in a bed of pine needles showed that the model’srnpredictions are very sensitive to the sub model used to estimate the flames height and the respectivernempirical models available in the literature do not describe well the present experiments.rnHowever, if the flames height is used as an extra input of the model, the rate of spread and thernprofile of the leading edge of the fire front in the fuel bed are predicted within the experimentalrnerrors. The prediction of the temperature history of the needles is worse but still satisfactory.