Localized heating ahead of flame front in wildland fire spread

Wildland fires are unpredictable and destructive events that cost enormous amounts of resources to fight and contain. It is pertinent to understand the underlying methods of heat transfer present in the flame spread of this nature. The current model for wildland fire spread assumes radiation-dominated heat transfer. This paper presents preliminary results that seek to investigate and qualify flame spread scenarios in which convective heat transfer (either buoyancy driven or forced) dominates radiative-driven heat transfer. Two sets of experiments were conducted: (1) a stationary line fire in a 92 cm x 10 cm rectangular trough to simulate a flame front, where embedded thermocouples in cylindrical aluminum rods were used to represent the unburned fuel particles and to measure the localized heating ahead of the flame front. (2) An engineered cardboard fuel bed was used where an IR camera fitted with flame filters was used to measure and record the temperature history of a fuel particle as it heats from ambient to ignition to ash. The preliminary results presented in this paper reveal influence of convective heating of the unburned fuel particles. In addition, the behavior of the fuel particles as they change through heating, ignition, and ash formation were monitored and recorded.