Uniform Propagation of a Planar Fire Front Without Wind

A physical model is proposed to describe the uniform propagation of a planar fire front through a randomly-packed horizontal fuel bed of thermally-thin cellulosic strands. The model assumes there is no ambient wind, and expressions are obtained for the forward rate of spread of the flame front and the surface temperature distribution of the unburnt fuel ahead of the fire. The model is tested against a laboratory fire. If only radiative inputs are included, the predicted rate of spread is thirteen times the measured value. The inclusion of convective cooling results in rate of spread agreement. The predicted unburnt fuel temperature profile then compares reasonably well with the observed values.