摘要
由于集中排烟模式能较好地控制上下游烟气的扩散范围,故被广泛应用于长大隧道设计中。文章针对小尺度火灾,建立了集中排烟隧道火源热烟羽受限发展理论模型,与已有火灾实验结果进行对比,完成了理论模型的验证,预测了顶板下方最高烟气温升、偏移距离等热参数。预测结果表明:火灾强度一定时,烟气最大温升随等效风速增加而急剧下降,且火灾强度对烟气温升的影响也较为显著;当等效风速超过1.5 m/s时,最大温升变化趋缓直至恒定;等效风速较小时,羽流未发生明显偏移,随着等效风速进一步增大,偏移距离明显增大,其变化速率随火灾强度的增大而减小。经回归整理得到了顶板下方烟气最大温升、偏移距离的无量纲准则关联式。
Because a concentred smoke extraction system enables the diffusion range of upstream and downstream smoke to be better controlled, it is widely used in the design of long tunnels. In this paper, a theoretical model of defined diffusion of a fire plume in a tunnel with a concentred smoke extraction system is established for a small-scale fire scenario, and these theoretical results are compared with experimental results to verify the theoretical model and predict such thermal parameters as the maximum temperature rise and the offset distance of smoke underneath the tunnel roof. The prediction results show that： 1） the maximum temperature rise of smoke drops sharply with an increase of equivalent wind velocity when the fire intensity is unchanged, and the fire intensity has a remarkable effect on the temperature rise; 2） when the equivalent wind velocity is over 1.5 m/s, the rising temperature will slow down until it becomes constant; 3） however, the plume has no obvious offset when the wind velocity is small, as its offset increases with an increase of wind velocity but its change rate decreases with an increase of fire intensity. Based on the regression method, a dimensionless criterion correlation is obtained regarding the maximum temperature rise and offset distance of smoke underneath the tunnel roof.
出处
《现代隧道技术》
EI
CSCD
北大核心
2015年第2期115-119,共5页
Modern Tunnelling Technology
基金
国家自然科学基金(51108254)
山东省自然科学基金(ZR2009FQ008)
关键词
理论模型
火灾强度
等效风速
最高温升
偏移距离
Theoretical model
Fire intensity
Equivalent wind velocity
Maximum temperature rise
Offsetdistance
