多孔介质隔热材料中的辐射热传递分析

On the Radiative Heat Transfer in the Porous Medium

新型的多孔材料以其重量轻、强度高备受航天工程设计人员的亲睐,尤其是作为隔热材料使用,可以说是航天工程热防护系统的热门材料。多孔介质在辐射热传递方面具有吸收发射和散射的功能,这些功能在其接受外来热流的作用下,于内部达到热能量平衡,求解这一平衡方程就可以求出辐射热流在材料中的分布。由于求解这一方程的困难,许多学者对材料特性作出了不同的简化,取得了多种近似的结果。文章不直接对材料特性做任何假设,而是根据预测模拟一个温度分布和热流强度的周向分量,采用分离变量法来求解热流强度,虽然分离变量法也关系到材料特性变化,然而可以根据曲线拟合法采取接近于实际的模拟,再通过迭代运算求得辐射强度更好的结果。

In the light of the light weight and high strength of the new type of porous materials, it is favoured by the designers of aerospace engineering, especially when it is used as insulation material, hence it can be reckoned as a demanding material in the heat protection systems of aerospace engineering. Radiative heat transfer associate with a porous medium consists of heat energy absorption, emission and scattering, which attain equilibrium under the external heat. Because of the difficulties in solving this equilibrium equation, many researchers made simplifications by making different assumptions on the material properties to obtain approximiate results. This paper is intended to avoid these assumptions, instead by simulating a predicted temperature distri- bution and radial intensity of radiation in method of separation of variable to solve for the radiative intensity. Although the method would in relation to changes of the material properties, through the method of curve fitting one could adjust the the simulations to make them more close to their true value, henceforth by iteration processes to obtain better result for the radiative intensity.