环境氧浓度对可碳化固体可燃物表面火蔓延的影响

在顺流风速为7．5cm／s、氧浓度分别为正常大气氧浓度0．9，1．0，1．1，1．2，1．3，1．4，1．5倍的条件下，测量了3mm厚的白木表面水平火蔓延速率及其上方的温度场特性。实验中观察到，在本实验条件范围内当来流氧浓度小于正常大气氧浓度的0．8倍（绝对氧浓度为16．8％）时火蔓延不能自发维持。当来流氧浓度高于正常大气氧浓度的0．9倍（绝对氧浓度为18．9％）时，随着氧浓度的逐渐增加，火蔓延速率以二次指数形式在增加。另外随着氧浓度的增加，固体表面上方火焰前锋处的温度场也出现了变化，固体表面上方最高温度出现的位置随着氧浓度的增加向远离表面方向移动，并且高温区域随着氧浓度的增加而逐渐变大。

Flame Spread over Charring Materials: the Influence of Ambient Oxygen Concentration

The flame spread velocity over the horizontal white wood surface which is 3 mm thick is measured,and so are the temperature profiles above its surface,when the flow velocity is about 7.5 cm/s,and the ambient oxygen concentrations are 0.9,1.0,1.1,1.2,1.3,1.4 and 1.5 times respectively of that in the ordinary air.In the experiments it is found that when the oxygen concentration is below 0.8 times of that in ordinary air,fire spread cannot be selfsustaining.When the oxygen concentration is higher than 0.9 times of that in ordinary air,the average velocity of flame spread seems to increase as a function of the square of oxygen concentration.And the temperature profiles at the flame front above the surface also change with the increase of ambient oxygen concentration.The location of highest temperature above the surface moves above and the high temperature area becomes larger with the increase of ambient oxygen concentration.