A Model for the Spread of Fire Across a Fuel Bed Incorporating the Effects of Wind and Slope

Abstract

A two-dimensional non-stationary model of a fire spreading across a bed of fuel is proposed incorporating the effects of wind and slope. The contributions of both radiative and convective preheating ahead of the fire-front are included. The radiation impinging on the top of the fuel-bed is determined, assuming the flame is a radiant surface. Convective heat transfer in the fuel layer is considered using a simplified description of the flow through the bed of fuel. Dedicated laboratory-scale experiments have been carried out across beds of pine needles for horizontal fire spread in still air, in order to validate the model. Experiments conducted under wind and slope conditions are also considered. Model predictions are then compared to these experimental measurements.

Testing of different skeletal and global mechanisms for modeling combustion of degradation gases involved in wildland fire

“…Thus, it leads to a slight overestimation of the temperature in the thermal plume. According to these results, to match the experiments, the mass fractions of CO, CH 4 and H 2 O must be equal to the values obtained during the gas analysis. The other combustible species have to be neglected.…”

“…Two mixtures were tested. For mixture 1, the mass fractions of CO, H 2 O, CH 4 and C 2 hydrocarbons correspond to the values of the gas analysis (Table 1). For composition 2, C 2 hydrocarbons were not considered.…”

“…At least three repetitions were carried out. Degradation gases mainly consist of CO 2 , CO, CH 4 , H 2 O, and lower amounts of H 2 , C 2 , C 3 and C 4 hydrocarbons ( Table 1).…”

“…Mixture 3 was established according to Grishin's hypothesis [5]. In this approach currently used in forest fire modeling, the mass fraction of CO is equal to the sum of the initial mass fractions of CO and CH 4 . In mixture 4, the mass fraction of CO corresponds to the same low heating value as mixture 2.…”

“…The second one incorporates empirical models [2]. Based on a detailed description of the heat transfer mechanisms, which govern the fire propagation, the physical models [3][4][5] are the third set of models. Recently, the new generation of physical models tends to include more and more physical mechanisms [6][7][8].…”