对称火源条件下聚氨酯泡沫顺流火蔓延研究

Study on the fire spread of polyurethane foam under symmetrical fire source conditions

利用自行搭建的小尺寸实验台探究对称火源条件下聚氨酯泡沫顺流火蔓延特征规律。研究结果表明:对称火源条件下聚氨酯泡沫顺流火蔓延特性主要受火源之间的热传递和受限夹角空间构型共同作用。顺流火蔓延过程中会伴随火焰分裂和分离现象,当对称火焰发生融合后板材表面温度场达到稳态;火蔓延在火焰出现交汇融合后,热对流换热占据主要地位,导致上部的辐射与气流速度总是高于下部,且上部辐射热通量在火焰融合区达到稳态;利用McCaffrey羽流模型得到稳定火焰区的火焰高度z以及z/Q^(2/5)的取值,同时运用自编MATLAB程序得到火焰高度,发现计算结果与试验现象吻合;火蔓延过程中质量损失率呈三段式线性分布关系,且在稳态燃烧区中火蔓延速率与热释放速率呈一定的幂次关系。

In this paper,we used a small-size experimental bench to investigate the downstream fire spread characteristics of polyurethane foam under symmetrical fire source conditions.The results of the study show that the spread characteristics of polyurethane foam under symmetric fire conditions are mainly affected by the heat transfer between fire sources and the restricted angle spatial configuration.The fire spread is accompanied by flame splitting and separation,and the temperature field on the surface of the sheet reaches a steady state when the symmetric flames fuse.The fire spread is dominated by thermal convection heat transfer after the flames intersect and fuse,resulting in the radiation and airflow velocity of the upper part is always higher than that of the lower part,and the radiant heat flux of the upper part reaches a steady state in the flame fusion zone.The values of flame height z and z/Q^(2/5) in the stable flame zone were obtained by using McCaffrey plume model,and the flame height was obtained by using a self-programmed MATLAB program,and the calculated results were found to be consistent with the experimental phenomena;the mass loss rate in the fire spreading process was linearly distributed in a three-stage relationship,and the fire spreading rate and the heat release rate in the steady-state combustion zone showed a certain power relationship.