低密度EPS不同角度及厚度情况下火蔓延特性研究

本文采用小尺寸实验的方法探究了低密度EPS火蔓延及其熄灭特性,分析了密度、厚度以及角度综合因素对EPS火蔓延及熄灭的影响。研究发现:密度为6 kg/m^3的EPS,由于密度很小,材料厚度以及放置角度受到密度影响的抑制,EPS均无法被火源点燃进而进行火蔓延;而当密度为10 kg/m^3的EPS,随着材料厚度以及放置角度的增加,试样经历了从不能点燃,到短距离不稳定火蔓延,正常蔓延,以及蔓延过程中收缩性熄灭等过程。研究发现,密度为10 kg/m^3,厚度为4 cm的EPS试样,当放置角度为0°、10°、20°和30°时,能够正常蔓延,而当角度增加至40°、50°时,EPS火蔓延过程中出现了收缩性熄灭的现象.通过分析火蔓延过程收缩性熄灭机理,发现火蔓延速度与预热区的长度之间的相互竞争机制,是导致熄灭现象产生的主要原因。实验结果表明,收缩性熄灭对火蔓延速度,池火区长度以及表面火焰区火焰形态等都产生了相应的影响。

Effects of Incline Angle and Thickness on Flame Spread over Low-density EPS

In this paper,a serious of small-scale experiments was carried out to reveal the effects of density,thickness and incline angle et al.comprehensive factors on EPS flame spread and extinction.It was found that,for EPS with a density of 6 kg/m^3,as the density is very small,the effects of thickness of the material and the incline angle are restrained by the influence of the density.Therefore,EPS could not be ignited by the fire source and go on flame spread.While,for the density of 10 kg/m^3 of EPS,with the increase of thickness and incline angle,the sample goes from non ignition,unstable flame spread in short distance,normal flame spread to shrinkage extinguishment.It was also found that,for the density of 10 kg/m^3 and the thickness of 4 cm of EPS,when the incline angles are 0°,10°,20°and 30°,the flame spreads normally.With the incline angle increasing to 400 and50°,the shrinkage extinguishment is formed,which can be attributed to the competitive mechanism between flame spread speed and preheating length,by setting up shrinkage extinguishment model.The experimental results show that,the flame spread speed,the pool fire zone length and flame shape in surface flame zone et al.are all influenced by the shrinkage extinguishment.