隧道火灾中火区阻力的理论研究

根据热流体学和通风学理论,对火区阻力的计算方法及影响因素进行研究。首先在修正的热阻力概念基础上建立热阻力的表达式,然后推导绕流阻力与火灾规模和风速的关系式,最终建立比较严谨的火区阻力实用公式,并得到数值模拟的验证。该式表明:在简化的物理模型中火区阻力与火灾规模成线性关系,与风速存在二次曲线关系;在风速不影响热释放速率的条件下,火区附加通风阻力与风速成正比,但对货车引起的隧道火灾,附加通风阻力与风速近似存在二次曲线关系。研究成果为火灾通风网络解算和防排烟方案的制定提供参考。

Study on Flow Resistance in Tunnel Fire Zone

Calculation method and influencing factors of flow resistance in tunnel fire zone were studied according to principles of thermofluid dynamics and ventilation.A formula of thermal drag was firstly established based on the revised concept,and then the relation between roundabout flow resistance,heat release rate(HRR) and airflow velocity was deduced.Finally,a formula for resistance in the fire zone was established and justified by numerical simulations.The formula indicates that resistance in fire zone is linear to HRR and quadratic to airflow velocity.And resistance in fire zone to airflow velocity is linear,if airflow velocity have no influence on HRR,but approximately quadratic,in case of a fire happening to a heavy goods vehicle(HGV).The results provide theoretical reference to ventilation network calculation and smoke control scheme in the event of tunnel fire.