Flame Spread Behavior Over Quartz Sand Soaked with Ethanol

Abstract

The flame spread over soaked sand is different from other kinds of fires and is not well understood. In this work, the flame spread behaviors over porous solids soaked with a low-viscosity highly volatile flammable liquid, ethanol, were studied. High-speed schlieren system, DV and thermocouple were employed to record the flame spread behavior. The liquid surface height and initial temperature can be changed by changing the combustible layer of premixed vapors, such as concentration or thickness. When the sand initial temperature is less than the stoichiometric temperature, Tst, an increase in sand temperature could cause an increase in flame spread rate. If the initial temperature is higher than Tst, the flame spread velocity almost remains constant at a high value. When the initial temperature is less than Tst, the flame spread rate decreases when the sand diameter increases. If the initial temperature is higher than Tst, the flame spread rate is constant and almost not influenced by the increase of sand diameter. When the liquid surface height is equal to 0 cm and the initial temperature is less than Tst, the flame spread over the porous solids depends on the gas heat conduction around the leading edge of the flame.