不同点火位置时乳胶泡沫火蔓延特性

Flame spread characteristics of latex foam at different ignition positions

在边缘点火和中间点火条件下对多孔乳胶泡沫进行小尺寸燃烧,研究了不同点火位置时火焰的蔓延过程和规律,考察了材料表面温度分布、火蔓延速率和火焰高度随时间的变化.结果表明,边缘和中间点火时,平均火蔓延速率分别为0.42和0.24cm/s,蔓延至整个材料表面的时间分别为84和74s,最大火焰高度分别为68.6和82.7cm.随火焰区不断增大,火焰温度不断升高,传递给未燃区的热量增多,加速了材料热解,火蔓延速率增大.

Natural latex based furniture is widely used in our daily lives. However, it is very easy to be ignited. Once ignited, fire could spread remarkably fast companied with a large amount of heat, smoke and fumes, which are extremely harmful to human beings. It makes sense to study the flame spread of latex foam. In this paper, the influence of ignition positions on the flame spread characteristics of latex foam were analyzed experimentally using a small-scale experimental setup and the ignition point was put on the center and edge of the specimen. The surface temperature profiles, flame height and flame spread rate were measured. The results showed that the latex foam combustion process can be divided into 5 stages： heat absorption, pyrolysis, ignition, heat transfer and flame spread. The flame spread direction was from the center to the edge showing a circle shape for the center ignition conditions. For the edge ignition condition, flame spread from one edge point to the diagonal point with the shape of sector. The average flame rate and the time of flame spread to whole surface of material for edge ignition condition were much higher than that of the center ignition condition. The average flame rates for edge and center ignition conditions were 0.42 and 0.24 cm/s, respectively. However, maximum flame height under edge ignition condition showed a lower value than those under center ignition condition, which is 68.6 cm comparing to 82.7 cm. The scale of burnt zone under two conditions expanded gradually with an increase of flame temperature. Therefore, more energy was passed to unburnt zone, which led to the speed up of material pyrolysis and the increase of flame spread rate. The heat transfer mechanism of the sample was investigated. In practice, this study can have a practically guiding meaning for fire protection and rescue.