In recent decades, double-skin façades (DSFs) have gained popularity in modern commercial buildings. However, their cavities can potentially accelerate flame spread, raising significant concerns regarding façade fire safety. Given that existing studies focus on the DSF component failures and fire stop measures without modeling validation, this study presents real-scale DSF fire experiments and modeling in accordance with JIS A 1310, conducted without combustibles to clarify fire behaviors within the cavity. The experiments employ HRRs of 600–900 kW and cavity depths of 0.4 and 0.8 m, highlighting that flame attachment to the facing wall is dependent on HRRs rather than cavity depths. Subsequently, Computational Fluid Dynamics (CFD) is utilized to investigate DSF fires, with validation against experimental temperature distribution and flame morphology. Furthermore, the validated CFD modeling is applied to scenarios with extended cavity depths and varied opening shapes, indicating that a cavity depth of ≥0.7 m mitigates flame spread for an opening ratio of n ≥ 1. The Modified-McCaffrey-Yokoi (MMY) model is proposed to characterize façade flame temperatures across varied cavity depths, and its convergence, featured by opening shapes and HRRs, is categorized to distinguish cavity flame behavior.

中文翻译：

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空腔火焰在双层立面蔓延的实验和数值研究


近几十年来，双层幕墙 （DSF） 在现代商业建筑中越来越受欢迎。然而，它们的空腔可能会加速火焰蔓延，从而引起人们对立面消防安全的严重担忧。鉴于现有研究侧重于 DSF 组件失效和防火措施，而没有建模验证，本研究根据 JIS A 1310 提出了真实规模的 DSF 火灾实验和建模，在没有可燃物的情况下进行，以阐明空腔内的火灾行为。实验采用 600-900 kW 的 HRR 和 0.4 和 0.8 m 的腔深，强调火焰附着在饰面壁上取决于 HRR 而不是腔深。随后，利用计算流体动力学 （CFD） 研究 DSF 火灾，并根据实验温度分布和火焰形态进行验证。此外，经过验证的 CFD 模型适用于空腔深度增加和开口形状不同的场景，表明 ≥0.7 m 的空腔深度可以减轻 n ≥ 1 的开口比的火焰蔓延。提出了 Modified-McCaffrey-Yokoi （MMY） 模型来表征不同空腔深度的立面火焰温度，其收敛性以开口形状和 HRR 为特征，以区分空腔火焰行为。