Flame Characteristics for Fires in Southern Fuels

Abstract: Equations describing flow in bouyant turbulent jets have been applied to the derivation of characteristics for forest fire flames. Approximate solutions are used to develop relationships for flame lengths, angles, heights, and tip velocities for fires heading with the wind and burning in calm air as functions of Byram's fire intensity. I. (Btu/ft-sec). Flame length and velocity relationships are tested with data taken during controlled burns in southern fuels and with data from the literature. Backfire data are described by the equations for calm-air conditions. Both theoretical and experimental results show that flame lengths for backfires and headfires vary as I-2/3 and I-1/2, respectively; flame tip velocities vary as I-1/3 and I-1/2.