Experimental Studies on the Effects of Spacing on Upward Flame Spread over Thin PMMA
Experimental Studies on the Effects of Spacing on Upward Flame Spread over Thin PMMA
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DOI：
10.1007/s10694-016-0590-6
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发表时间：
2016-04
期刊：
影响因子：
3.4
通讯作者：
Hui Zhu;Guoqing Zhu;Yunji Gao;Guoxiang Zhao
中科院分区：
文献类型：
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作者：
Hui Zhu;Guoqing Zhu;Yunji Gao;Guoxiang Zhao
通过实验研究了薄壁燃料与壁面间距对火焰向上传播的影响。通过视频图像分析，分别以2 mm、7 mm、13 mm、19 mm和25 mm的间隔测量前焰高度、后焰高度、热解高度、燃烬长度和热解扩散速率。实验在高度为200 mm、宽度为50 mm、厚度为1 mm的均匀PMMA（聚甲基丙烯酸甲酯）样品上进行。结果表明：(1)随着间距的增大，前焰高度、后焰高度、热解高度、燃尽长度均呈现先增大后减小的变化规律；在壁高的6.5%间距处观察到最大轨迹。(2)无限大长度PMMA时，热解区和热解扩展速率达到渐近稳态，热解扩展速率和燃尽扩展速率渐近相等。(3)特别令人感兴趣的是由于辐射通量增强，壁间距/样品高度比（0.065）的最大质量损失率。本研究首次利用1mm厚的PMMA薄板，包括双面燃烧情况，研究了壁面与燃料间距对火焰向上传播的影响。
Experiments were carried out to study the effect of spacing between wall and thin fuels on upward flame spread. The front flame height, back flame height, pyrolysis height, burnout length, and pyrolysis spread rate were measured by video image analysis with spacings of 2 mm, 7 mm, 13 mm, 19 mm, and 25 mm. Experiments were performed on uniform PMMA (polymethyl-methacrylate) samples with 200 mm height, 50 mm width, and 1 mm thickness. The results are as follows: (1) As the spacing increased, the front flame height, back flame height, pyrolysis height, and burnout length showed the same trajectory, first increased and then decreased. The maximum trajectory was observed at a spacing of 6.5% of the wall height. (2) At an infinite length of PMMA, the pyrolysis zone and pyrolysis spread rate would reach an asymptotic steady state, and the pyrolysis and burnout spread rates will be asymptotically equal. (3) Of particular interest is the maximum mass-loss rate for a wall spacing/sample height ratio (0.065) due to enhanced the radiation fluxes. In this study, the effects of spacing between wall and fuels on upward flame spread was investigated for the first time using 1 mm thick PMMA sheets, including two-face burning case.