半透明介质相变中的辐射变物性问题

Variable Radiative Property Problem in Phase-Change Inside a Semitransparent Medium

半透明介质相变传热在许多工程领域引起关注,其实质是变物性条件下伴随相变的辐射导热瞬态耦合传热问题,其难点在于相变过程中的辐射变物性问题,尤其是折射率的时空演变问题。本文首次研究相变过程中的变折射率问题。假设相变介质存在固相糊状液相区,固/糊界面、液/糊界面假定为半透明漫反射。采用多层辐射传递模型模拟相变介质内的辐射传递问题,考虑折射率分布在相变过程中随相变时间的变化及随相态空间的转换,研究其对相变辐射耦合传热的影响。结果表明,半透明介质相变过程的变折射率问题不可忽视。

Phase-change heat transfer in a semitransparent medium is the focus of many engineering fields.Its essence is the transient coupled heat transfer of radiation-conduction with phase change under the condition of variable physical properties.The difficulty is to solve the variable radiative property problem,especially the problem for the variation of refractive index with space and time in phase change.This paper first investigates the problem of variable refractive index in phase change. The phase-change medium is assumed to have solid,mushy and liquid zones,and the solid/mushy and liquid/mushy interfaces are considered to be semitransparent and diffuse reflecting.Using multilayer radiative transfer models,the radiative transfer in the phase-change medium is simulated.Considering the change of refractive index distributions with phase-change time and phase states,its effects on the coupled heat transfer of phase change and radiation are examined.The results show that the effects of variation of refractive index could not be neglected in phase change inside the semitransparent medium.