To investigate the combustion characteristics of polymethyl methacrylate (PMMA), a series of experiments of PMMA combustion with different sample shapes and sizes in still air are performed. A digital video camera and an electronic balance are used to record the combustion process and variation of mass, particularly. The effects of equivalent diameter on combustion are discussed and analyzed, respectively, to well adapt in dimensionless analysis methods. Flame pulsation during the stable burning stage is studied by similarity theory and dimensionless analysis methods. Experimental and theoretical results show that correlations between flame pulsation and equivalent diameters in PMMA burning are similar to that of pool fires, that is, flame pulsation frequency is inversely related to the square root of equivalent diameter. In addition, the corresponding theoretical analysis of heat and mass transfer processes is studied. Convection and radiation heat transfer were calculated and modeled for each shape and sample size. Based on the heat transfer calculation results, sample mass loss rate for each sample size was predicted, and it is in good agreement with the experimental result. Finally, a dimensionless heat release rate for different sample size was scaled with dimensionless flame height.

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不同当量直径PMMA片材在静止空气中的燃烧特性

为了研究聚甲基丙烯酸甲酯 (PMMA) 的燃烧特性，进行了一系列不同样品形状和尺寸的 PMMA 在静止空气中燃烧的实验。特别是使用数码摄像机和电子天平来记录燃烧过程和质量变化。分别讨论和分析了当量直径对燃烧的影响，以适应无量纲分析方法。采用相似理论和无量纲分析方法研究了稳定燃烧阶段的火焰脉动。实验和理论结果表明，PMMA燃烧中火焰脉动与当量直径的相关性与池火相似，即火焰脉动频率与当量直径的平方根成反比。此外，研究了传热传质过程的相应理论分析。对每种形状和样品尺寸的对流和辐射传热进行了计算和建模。根据传热计算结果，预测了各样品尺寸的样品质量损失率，与实验结果吻合较好。最后，不同样品尺寸的无量纲放热率与无量纲火焰高度成比例。