宽度变化对聚苯乙烯保温材料水平火蔓延预热角度的影响

摘要

研究聚苯乙烯保温材料水平火蔓延过程中,样品宽度变化对预热角度的影响以及预热角度变化对火蔓延行为及火蔓延速率的影响.研究结果表明:样品刚被点燃时其表面的水平火蔓延速率比样品中部及底部快,当样品燃烧到达稳定阶段时,样品水平火蔓延速率呈现相对均一及稳定的状态,最终形成明显的预热角度,并且预热角度随着样品宽度的增大先增大后减小,而水平火蔓延速率则先减小后增加.此外,根据能量守恒原理,预热角度减小将增强样品的热传递效应,使样品得到更多热量进而导致火蔓延速率增大,因此,预热角度与火蔓延速率呈负相关关系.%During the horizontal flame spread over XPS slabs,the effects of sample width on the angle and the influence of the angle on flame spread behaviours were investigated.The results show that at the initial stage the flame spreads faster at the slab surface than the other parts and eventually forms the pyrolysis angle at steady stage.The magnitude of pyrolysis angle increases firstly and then decreases with the increase of the sample width.However,the horizontal flame spread rate decreases at first and then increases with the increase of sample width.Moreover,according to the energy conservation,reducing the pyrolysis angle will enhance the heat transfer into the sample and thus lead to higher flame spread rate,which justifies the opposite trends of pyrolysis angle and flame spread rate.