孔隙随机结构对非均质多孔泡沫导热性能的影响

多孔泡沫是一类低密度、高比表面积、具有独特性能的新型功能材料。实际多孔泡沫材料通常是非均质的，即其孔隙结构分布是随机的。为研究非均质多孔泡沫材料的导热性能，提出用孔隙均匀度作为表征孔隙结构分布随机性的参数，以多孔石墨泡沫为例，分析孔隙均匀度对多孔泡沫有效热导率的影响。数值计算结果表明：孔隙结构分布越不均匀，多孔泡沫材料的导热性能越差。根据计算结果提出了非均质石墨泡沫相对有效热导率的预测式，并与现有文献报道的结果进行了比较，发现当前结果呈现了孔隙结构随机性对材料有效热导率的影响，与ORNL实验结果更吻合。

Influence of random porosity structure on thermal conductivity of heterogeneous porous foam

Porous foam is a novel functional material, which have low density, high specific surface area and particular performance. However, porous foam is always heterogeneous, the distribution of pore structure is random. In this study, a random parameter, pore uniformity U, is proposed to study the thermal conductivity of heterogeneous porous foam and analyze the influence of pore uniformity on its effective thermal conductivity based on graphite foam. Numerical results show that the thermal conductivity of porous foam material decreases with the increase of the randomness of pore structure. A relationship between pore uniformity, porosity and thermal conductivity of heterogeneous graphite foam is proposed and compared with those in literature. The present results are in reasonable agreement with the measured data of ORNL and reflect the influence of pore structures.