Flame spread over ground soaked with highly volatile liquid fuel

Abstract

Flame spread characteristics over ground which has soaked up a highly volatile liquid fuel and whose temperature is above the flashpoint of the spilled fuel were studied experimentally. N-octane and a bed of glass beads were used as the fuel and the ground model, respectively. The effects of the temperature of the glass beads bed, the diameter of glass beads, the surface inclination angle of the glass beads bed, the thermal conductivity of the ground surface and the elapsed time from fuel spillage to ignition, on the flame spread characteristics and on the flame spread velocity were studied in detail. Whether or not the ground temperature is above the stoichiometric temperature for the combustion of spilled liquid fuel in air has the largest effect on the flame spread characteristics and on the flame spread velocity. When the ground temperature is below the stoichiometric temperature, even if it is above the flashpoint, the increase in diameter of the beads and in downward inclination angle of the ground surface, and the decrease in ground temperature, all lower the flame spread velocity. The velocity is considerably lower than that over the liquid-fuel pool. When the ground temperature is above the stoichiometric temperature, however, the effects of such parameters disappear. The flame spread velocity is extremely high and is constant (about 150 cm/sec), regardless of the bed temperature, and is equal to that over the liquid fuel pool.