The Detailed Processes Involved in Flame Spread over Solid Fuels

Abstract

Abstract The variation of the flame propagation rate across a thermally-thick fuel as a function of opposed flow velocity is described as consisting of three regimes. The first at low opposed flow velocities is dominated by the naturally induced flow and shows relatively little variation of the propagation rate. The second regime shows a near linear increase of propagation rate with opposed flow and is dominated by thermal processes alone. The last regime shows a decline in rate with opposed flow and is an indication of the dominance of chemical rate processes. Surface temperature and flow field measurements ahead of the flame indicate that the mechanism by which the flame propagates is not by thermal conduction through the solid ahead of the flame, but rather by fuel diffusing from behind the flame through the quench layer to create a lean flammable mixture ahead of the flame.