Flame merging is deemed to enhance the burning intensity and make the fire more destructive. This paper presents an experimental study on merging behaviors of two same rectangular heptane pool fires with long sides parallel. The pan aspect ratio was set 2–4 and the spacing was changed. The burning rate and flame height were measured. As the spacing decreases, the flame shape was divided into five regions, i.e., (I) no interaction, (II) tilt but non-merging, (III) intermittent merging, (IV) upper flames fully merging but lower flames separated and (V) flames merging from the pan base. The results showed that both the burning rate and flame height increase within the stages I–IV and then decrease in stage V. A normalized parameter ψ is introduced to characterize the air entrainment restriction. A unified correlation between burning rate and ψ is then developed. Connecting with the theoretical force analysis, the criteria of merging from the base and beginning merging are determined as ψ = 0.33 and ψ = 0.61. Then a piecewise correlation of the merging flame height is established. The proposed correlations for burning rate and flame height are verified using present and literature data and their scope of application is further expanded into square pool fires.

中文翻译：

---

引气限制度对静止空气中两平行矩形池火燃烧特性影响的定量分析

火焰合并被认为可以增强燃烧强度，使火灾更具破坏性。本文介绍了两个长边平行的相同矩形庚烷池火的合并行为的实验研究。平移纵横比设置为 2-4，间距发生变化。测量燃烧速率和火焰高度。随着间距的减小，火焰形状分为五个区域，即（I）无相互作用，（II）倾斜但不合并，（III）间歇合并，（IV）上火焰完全合并但下火焰分离和（ V) 火焰从锅底融合。结果表明，燃烧速率和火焰高度在阶段 I-IV 内增加，然后在阶段 V 中降低。引入归一化参数 ψ 来表征空气夹带限制。然后建立燃烧速率和 ψ 之间的统一相关性。结合理论受力分析，确定从底部合并和开始合并的标准为ψ = 0.33 和ψ = 0.61。然后建立合并火焰高度的分段相关性。使用现有数据和文献数据验证了燃烧速率和火焰高度的建议相关性，并将其应用范围进一步扩展到方形水池火灾。