竖直狭缝内泡沫材料火蔓延的数值模拟研究

用FDS软件对泡沫材料在竖直狭缝内的火蔓延进行模拟计算。计算结果表明竖直火蔓延速度在狭缝宽度为6 cm时最大,而4 cm和8 cm情况下大约相同。对不同时刻壁面火焰的高度数据进行线性拟合,得出狭缝内泡沫层燃烧的火焰高度和单位宽度热释放速率关系为幂次的函数关系,其形式和前人的结论公式基本相同。但是,由于狭缝的作用和点火源的形式不同而存在一个单位宽度热释放速率校正的参数b。同时,由于通风受限,相对于开放空间,狭缝空间内火焰的高度随热释放速率的增加增长较慢。

A Study of the Numerical Simulation of Polyurethane Foam Fire Propagation in Vertical Crevice Structures

Fire Dynamics Simulation is performed to investigate the flame characteristics of the polyurethane foam fires in vertical crevices between two parallel walls at different slit widths. It is found that the vertical spread velocity of fire in 6 cm crevice is greater than 8 cm and 4 cm,of which two are almost the same. The linear fitting curves of flame height data at different time points indicate that there is a power function relationship between the flame height and the heat release rate per unit crevice width. The type of formula is consistent with the one proposed by Delichatsios et al. Due to the existence of the parallel walls and different forms of ignition sources,the new formula includes a heat release rate correction term compared with the former one. Besides,the flame heights of the polyurethane foam fires in the vertical wall crevices grow more slowly than freely propagating ones because of insufficient ventilation.