Flame tip traveling in boundary layer flow with flammable mixture along fuel-soaked ground

Abstract

From the point of view of a fundamental study on flame propagation along ground soaked with high volatile liquid fuels, the effect of an entrained flammable mixture by airflow toward theignition location on traveling of a flame tip along the fuel-spillage area was studied. The thickness of flammable mixture layer is about one tenth of that of velocity boundary layer ofthe airflow. After the onset of ignition, the flame tip travels through the thin flammable mixture layer in the airflow with large velocity gradient. The effect of airflow velocity on the traveling of flame tip (both of upstream and downstream) was investigated. The dependence of the flame tip traveling on the airflow velocity is classified into some regions by the ratio of the airflow velocity about 1 mm above the ground surface to the flame propagation velocity with no surrounding airflow. The critical airflow velocity for the blowoff of flame tip (upstream and downstream) strongly depends on the quantity of flammable mixture entrained toward the ignition location by the airflow.