Flame spread over porous solids soaked with a combustible liquid

Abstract

An experimental study has been performed of the flame spread over a layer of porous or non-porous glass beads soaked with kerosene. The aspects and rates of flame spread were examined in detail, and for typical cases, the temperature distributions in the glass bead layers were measured during flame spread. When a kerosene layer of more than one mm was present over the glass bead layer, the observed aspects and measured rates of flame spread were much the same as those over kerosene in a metal tray. On the contrary, when the kerosene level was close to or below the top surface of the glass bead layer, the flame spread rates were found to be comparable to those over combustible solids and the effects of glass bead characteristics on the flame spread were observed to become distinct. Based on the observed aspects and measured rates of flame spread and the temperature distributions in glass bead layer, it is pointed out that the phenomena characterizing the flame spread are the behavior of kerosene and the two-phase heat transfer through the mixed media of glass beads-gas or glass beads-kerosene. By considering the balance of surface tension, adhesion, and gravitation, the behavior and surface configuration of kerosene observed in the experiments are interpreted qualitatively. The mode of heat transfer to kerosene ahead of the leading flame edge is inferred to be the conduction and convection through the condensed phase.