Abstract This paper experimentally investigated the internal temperature and the facade flame for compartment fires involving circular openings. A series of experiments were carried out by using a reduced-scale model which composed of a cube compartment with various circular openings and a vertical fireproofing board (used as building facade). A porous burner with propane fuel was set inside the compartment as fire source. The internal temperature profile was measured by vertical thermocouple arrays at the inner and outer corners, and the facade flame was captured by a CCD camera from a side view. This paper revealed that: (1) With the same area, maximum heat release rate inside the compartment with circular opening is larger than that with square opening. (2) For relatively larger circular openings, facade flames tend to ceiling jet flame extension. With the increasing of heat release rate, facade flame induced by ceiling jet flame extension will convert to spill fire plume. (3) A dimensionless number R, which represents the ratio of total heat release rate to internal maximum heat release rate, is proposed to distinguish spill fire plume and ceiling jet flame extension when facade flames appear at exterior. (4) A non-dimensional correlation is developed to characterize the facade flame heights for both ceiling jet flame extension and spill fire plume. These findings and results can provide fundamental knowledge for understanding compartment fire with a circular opening.

中文翻译：

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圆形开口隔间火灾的实验研究：从内部温度和立面火焰方面

摘要 本文通过实验研究了圆形开口隔间火灾的内部温度和立面火焰。使用由具有各种圆形开口的立方体隔间和垂直防火板（用作建筑立面）组成的缩小比例模型进行了一系列实验。隔室内设置了一个装有丙烷燃料的多孔燃烧器作为火源。内部温度分布由内外角的垂直热电偶阵列测量，立面火焰由侧视图的 CCD 摄像机捕获。本文揭示： (1) 在相同的面积下，圆形开口的隔间内的最大热释放率大于方形开口的隔间。(2) 对于较大的圆形开口，立面火焰倾向于向天花板喷射火焰延伸。随着热释放率的增加，天花板喷射火焰延伸引起的立面火焰将转化为溢出的火羽。(3) 提出了一个无量纲数R，代表总放热率与内部最大放热率的比值，用于区分外立面火焰出现在外部时的溢出火羽和天花板喷射火焰扩展。(4) 开发了一种无量纲相关性来表征天花板喷射火焰延伸和溢出火羽的立面火焰高度。这些发现和结果可以为理解圆形开口的隔间火灾提供基础知识。代表总热释放率与内部最大热释放率的比值，用于区分外立面火焰出现时的溢出火羽和天花板喷射火焰扩展。(4) 开发了一种无量纲相关性来表征天花板喷射火焰延伸和溢出火羽的立面火焰高度。这些发现和结果可以为理解圆形开口的隔间火灾提供基础知识。代表总热释放率与内部最大热释放率的比值，用于区分外立面火焰出现时的溢出火羽和天花板喷射火焰扩展。(4) 开发了一种无量纲相关性来表征天花板喷射火焰延伸和溢出火羽的立面火焰高度。这些发现和结果可以为理解圆形开口的隔间火灾提供基础知识。