基于热解过程的EPDM变热物性数值传热

针对三元乙丙橡胶(EPDM)类绝热材料热载荷作用下的热解炭化过程,基于热解动力学和多孔介质传质传热理论,建立了芳纶/EPDM绝热材料热物性参数随温度和时间变化的变热物性模型,并通过与实验的对比,验证了模型的准确性与可靠性。随后对热载荷作用下的烧蚀热响应开展了数值计算,结果表明:热载荷作用初期,材料表面升温迅速,随着能量不断传递,温度推进速率明显降低,炭化层厚度增长减慢,部分材料仍为原始状态；温度对热解反应速率的影响呈指数级,距表面越近反应速率越快,反之则慢。所提出的变热物性模型对绝热材料的烧蚀研究具有一定的参考价值。 

Numerical heat transfer of EPDM with variable thermal properties based on pyrolysis process

In order to study the pyrolysis ablation process of ethylene propylene diene monomer (EPDM) insulator under thermal load, a variable thermal properties model, in which the thermal properties of aramid/EPDM insulator vary with temperature and time, was established based on pyrolysis kinetics, mass and heat transfer theory of porous media. The accuracy and reliability of the present model were verified by comparing with experimental results. Then numerical calculations for the ablation thermal response under thermal load were carried out. Results showed that at the initial stage of thermal loading, the surface of the material heated up rapidly. As the energy continued to transmit, the temperature advancement rate and the charring layer thickness reduced significantly, and the part of the material was still in their original state. The effect of temperature on the pyrolysis reaction rate presented an exponential trend. The closer to the surface reflected the faster reaction rate and vice versa. The variable thermal properties model has certain reference value for the ablation research of thermal insulation materials.