Experimental Study On Flame Spread Over Typical Charring Combustibles At Different Altitudes

Fire disaster is the combustion phenomenon that out of control in the space and time, which caused many bad disasters to the human and society. However, flame spreading over combustibles is the common burning phenomenon occurring in forest fires, industry fires and building fires, and also a fundamental problem in the field of fire research. Exploring the characteristics of flame spread over the surface of solid combustibles and building the theoretical models of fire spread are the self-demand of fire science development.In this paper, three kinds of charring combustibles(Whitewood, Camphor wood, Chinese fir) with various widths were chosen to explore the characteristics of flame spread under different inclinations, low pressure and oxygen concentration(Lhase area).In Hefei, the effects of width on the characteristics of flame spread of different kinds of samples were explored. Flame height, flame temperature, surface temperature of sample and flame spread rate was measured. In Hefei area, flame height increased with the increase of sample width when the sample width was confined to a narrow range. With the same width, the flame height of Camphor wood was the highest of three, while the flame height of Chinese fir was the lowest. With the same inclination and width, the flame spread rate of Chinese fir is bigger than that of White wood, while the flame spread rate of Chinese fir was the smallest. In addition, the surface temperature of Camphor wood decreased with the increase of the sample inclination.In Lhasa, the characteristics of flame spread under sub-atmospheric and low oxygen concentration were explored, and comparison was made with the characteristics of flame spread in Hefei. The results showed that the flame height of the same kind of sample with the same width in Hefei was higher than that of Lhasa. At the same time, the pulsation frequency in Hefei was larger that that of Lhasa when the width of the sample was small (less than 5cm). Under the influence of low ambient pressure and oxygen concentration, the flame spread rate of Whitewood decreased, and the influence of the low ambient pressure and oxygen concentration on the flame spread over the Whitewood decreased with the increase of width. In additionally, under the influence of low pressure and oxygen concentration, the temperature of flame in Lhasa is higher than that in Hefei because of the weaker natural convection and decreased number of carbon particles in the flame.