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Experimental investigation of the confinement effect on a flame impinging a ceiling in an enclosure
Fire Safety Journal ( IF 3.4 ) Pub Date : 2021-04-04 , DOI: 10.1016/j.firesaf.2021.103344
A.J. Wang , B. Manescau , K. Chetehouna , C. De Izarra , S. Rudz

This experimental study highlights the confinement effect on a flame impinging a ceiling in confined or semi-confined environment. The enclosure used in this study represents a 1:10 scale model of a student compartment with two possible openings: a door and a window. It is developed based on the conservation of the Froude number in scaling law. The objective of this work is to provide explanations in terms of fire safety on thermal phenomena that can occur during fires in closed environments, for example in a room of a university residence, regarding eight heat rates release of fuel and five confinement levels. A flame oscillation modelling of propane-air flame is proposed and is verified by the experimental results. It is shown both by theoretical modeling and experimental results that the confinement of a compartment has an effect on period time of flame oscillation. Moreover, experimental results show that the confinement level of compartment is a key parameter to characterize vertical temperature evolution both in the center (impinging zone) and near the wall in the enclosure. The correlations for normalized gas temperature rise near the wall are proposed and these temperature evolutions are bounded by the ventilation conditions of the five configurations. Indeed, under condition of equivalence ratio greater than 1, the maximum gas temperature near the wall of a certain heat release rate decreases dramatically with the increasing of configurations' confinement levels, which is associated to the decrease in flame intensity by lack of oxygen with a great criterion of under ventilation.



中文翻译:

限制火焰撞击外壳中天花板的实验研究

这项实验研究强调了在密闭或半密闭环境中对撞击天花板的火焰的限制作用。本研究中使用的围护结构代表了一个具有两个可能开口的学生隔间的1:10比例模型:门和窗户。它是基于比例定律中的弗洛德数守恒而开发的。这项工作的目的是就在封闭环境中火灾(例如在大学宿舍的房间内)中可能发生的热现象的消防安全性提供解释,涉及释放燃料的八个热率和五个限制等级。提出了丙烷-空气火焰的火焰振荡模型,并通过实验结果进行了验证。理论模型和实验结果均表明,隔室的封闭对火焰振荡的周期时间有影响。此外,实验结果表明,隔室的限制水平是表征外壳中央(撞击区域)和壁附近的垂直温度变化的关键参数。提出了壁附近归一化气体温度升高的相关性,并且这些温度演变受五种配置的通风条件限制。实际上,在当量比大于1的条件下,具有一定放热率的壁附近的最高气体温度会随着构型的约束水平的增加而急剧下降,

更新日期:2021-04-15
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