辐射热流下有限厚度PMMA着火特性研究

探究透明PMMA（聚甲基丙烯酸甲酯）厚度和4种不同恒定热流对材料表面温度、质量损失率、着火时间及着火温度的影响。利用反演模型并结合部分实验数据得到PMMA的热物性参数，将其他工况模拟结果与实验测量值及理论分析值相互对比，验证了数值模型和理论分析的准确性和可靠性。结果表明，PMMA着火时间的下降趋势随热流的增大而逐渐变缓。PMMA厚度小于3 mm时，表面温度和质量损失率随厚度增大而减小。PMMA厚度大于3 mm时，着火温度的平均值为（628±20） K，其着火特性几乎不随厚度的变化而变化，故着火温度可作为PMMA着火判据。

Ignition characteristics of finite thick PMMA exposed to thermal radiation

Influence of sample thickness and four prescribed constant heat fluxes on surface temperature, mass loss rate, ignition time and critical temperature of clear PMMA (Polymethyl Methacrylate) was investigated. Inversing modelling was utilized incorporating experimental measurements to determine the thermodynamics and kinetics of PMMA, which were employed as inputs of the numerical model to simulate the other scenarios. Accuracy and reliability of the numerical model were verified by comparing with experimental results and analytical correlations. The results showed that the declining rate of the ignition time decelerates with increasing heat flux. When the thickness of PMMA was less than 3 mm, the surface temperature and mass loss rate decrease with increasing thickness. As the thickness gets larger than 3 mm, the average ignition temperature was （628±20） K, and no sensible dependency on thickness was detected, indicating that the ignition temperature can be employed as ignition criterion.