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Abstract
Experiments were conducted wherein wood shavings and Ponderosa pine needles in quiescent air were subjected to a steady radiation heat flux from a planar ceramic burner. The internal temperature of these particles was measured using fine diameter (0.076 mm diameter) type K thermocouples. A narrow angle radiometer was used to determine the emissive power generated by the burner. A model was developed to predict the steady-state temperature of a cylindrical particle with an imposed radiation heat flux under both quiescent air (buoyancy-induced cooling) and windy (forced convection cooling) conditions. Excellent agreement was observed between the model predictions and the experimental data. Parametric studies using the validated model explore the effect of burner (flame) temperature and distance, fuel size, and wind speed. The data suggest that ignition of the fuel element by radiation heating alone is likely only under circumstances where the fire is very intense (such as crown fires), and even then may still be dependent on pilot ignition sources.