自然通风房间内细水雾与油池火作用的数值模拟

Numerical Study on the Interaction of Water Mist and Pool Fire in Natural Ventilation Compartment

采用大涡模拟、混合物分数燃烧模型和欧拉-拉格朗日粒子运动描述法,对自然通风房间内细水雾与油池火焰作用过程进行数值模拟;探讨细水雾在火羽流的不同区域内的灭火机理;分析雾滴直径在自然通风条件下对细水雾灭火效果的影响。模拟结果表明:细水雾冷却热烟气层分为温度迅速降低和缓慢下降两个阶段;在间歇火焰区和浮力羽流区以及热烟气层主要发挥细水雾的蒸发冷却作用,在恒定火焰区则是蒸发冷却和隔氧窒息共同作用;着火区域封闭性较差时,直径较小的水雾系统的灭火效果较低。

To probe into the extinguishing mechanism of water mist in different regions of fire plume and analyze the influence of droplet diameters on the extinguishment effect, a numerical simulation was carried out on the interaction of water mist and pool fire in natural ventilation compartment by adopting Large Eddy Simulation（LES） , Mixture Fraction Combustion model and Euler-Lagrange method. The results showed that the cooling process of smoke layer by water mist included the sudden drop stage of temperature and the gradual drop stage of temperature. In the intermittent flame, buoyant plume and hot ceiling smoke layer, the main suppression mechanism was the evaporative cooling of water mist, while in the persistent flame, the dominant suppression mechanism was the co-work of evaporative cooling and oxygen asphyxiation. Furthermore, the droplets with smaller diameters have a lower extinguishing effect on the compartment fire with good ventilation.