基于FDS的建筑外立面墙相邻双窗口溢流火行为研究

前人单窗口溢流火理论不足以适用于多窗口，且两者溢流火行为存在明显差异。为探究多窗口溢流火现象及机理，基于FDS 建立两种建筑模型，并在立面墙上设置两个平行窗口，研究火源功率（HRR）与窗口间距（D）对平行双窗口溢流火行为、室内空气流率、溢流火焰高度（Hef）以及上层建筑立面墙的影响。结果表明：通风型控制火灾中，空气质量流率系数k 会随着D 的增加不断减小最终趋于稳定；而燃料控制型中，HRR 越大k 越大，且在同一个HRR 工况下，随着D 增大k 会先增大后减小，然后趋于稳定。相同D 下，HRR 越大Hef 越高，同一HRR 下，随D 的减小Hef 先减小后增加，即存在临界转变间距D*，HRR 越大，D*越大。Hˉef/ξ1= cQ*ex2/5 仅适用于单一窗口或多窗口之间影响很小即相对独立的窗口。双窗口溢流火对上层建筑立面墙的危险性远大于单窗口溢流火。D≤1 m 的范围内，立面墙接受热量的面积随着D的增加而增加。

Study on overflow fire behavior of parallel double windows on facade wall out of building based on FDS

The former theory of single window overflow fire is not suitable for multi window, and there are obvious differences between them. In order to explore the phenomenon and mechanism of multi window overflow fire, two building models were established based on FDS, and two parallel windows were set up on the facade wall. The influence of fire source power (HRR) and window spacing (D) on the behavior of overflow fire in parallel double windows, indoor air flow rate, height of overflow flame (Hef) and superstructure facades were studied. The results showed that in the ventilation control fire, the air mass flow rate coefficient k decreases with the increase of D, and finally tends to be stable. In the fuel control fire, the larger the HRR, the greater the k. Under the same HRR, with the increase of D, k increases at the beginning and then decreases, and then tends to be stable. Under the same D, the bigger the HRR, the higher the Hef. Under the same HRR, with the decrease of D, Hef decreases at the beginning and then increases. That is, there is a critical transition distance D*, and the larger the HRR, the greater the D*. H ˉef /ζ1 = cQ* 2/5 ex is only applicable to single window or relatively independent window with little influence among multiple windows. In the range of D≤1 m, the heat receiving area of facade increases with the increase of D.