基于中性面的抑制烟气溢流的临界排烟量模型  

Calculation model of critical smoke exhaust rate to suppress overflow based on the neutral plane

作　　者：毛少华[1,2] 李元洲[1] 杨立中[1] 李健[1] 李成龙[1] 

机构地区：[1]中国科学技术大学火灾科学国家重点实验室,合肥230027 [2]中国舰船研究设计中心,武汉430064

出　　处：《安全与环境学报》2013年第1期203-207,共5页Journal of Safety and Environment

基　　金：国家重点基础研究发展计划项目(2012CB719704);安徽省自然科学基金项目(1040606M117)

摘　　要：本文基于中性面理论,建立了排烟条件下房间(简称排烟房间)竖向开口烟气中性面计算的区域模型。根据中性面高度与开口上沿的关系,得到了抑制开口处溢流产生所需的临界排烟流量以及气体流入质量流率的计算模型。结果表明:在排烟条件下,房间竖向开口处烟气流动的主要控制因素仍是密度差引起的压差;随着排烟量增大,开口处的中性面不断上移,烟气溢流量持续减小。中性面与开口上沿平齐后即达到溢流抑制临界条件,烟气便不再溢出室外。数值模拟结果与理论模型的计算结果对比表明,所建立的模型可以较好地预测排烟房间竖向开口的烟气溢流抑制临界条件。The present paper intends to propose a renovated calcula- tion model of critical exhaust rate needed to suppress the smoke belching out of the burning room via the vertical outlets, such as door or window. It is often the case that the neutral plane is foundation of the research of smoke flow in vertical outlet. Thus, we have estab- lished a model of neutral plane in the vertical smoking-outlet for a room with a ventilation system based on the zone model and Bernoulli Equation in this paper. Comparing the amount of the overflow under different relative positions of a neutral plane and the upper side of the outlet, the critical condition for suppressing the smoke overflow can be defined as the neutral plane height should be equal to the height ofthe upper side. As a result, we have gained our calculation model of critical exhaust rate of the ventilation system and the mass flowing rate into the burning room through the outlet. The input indexes for the model include： the outlet width, its height, the exhaust rate and the smoking temperature in the burning room. In order to verify the pro- posed model, we have developed a full-size room model for numerical simulation by using the Fire Dynamics Simulator （FDS the 5.5.3 ver- sion）. With the above said model, we have done a series of numeri- cal simulation of 12 groups at different exhaust rates to study the smoke flow in the vertical outlet under the ventilation conditions. The results indicate that： if there the ventilation works in the room, the smoke current in the vertical outlet would also be able to change lin- early with the height, which demonstrated that the main driving force of the smoke flow in vertical oudet is still attributed to the pressure difference which is caused by the density difference; For the tempera- ture in the burning room, which increases with height, the smoke ex- haust rate has only a relatively small influence on its distribution. When the exhaust rate is relatively small, it is clear that there exists a neutral plane in vertic

关 键 词：安全工程 烟气 开口 中性面 溢流 排烟量 

分 类 号：X932[环境科学与工程—安全科学]