同心壳层结构中超声速扩散辐射波的几何自由程

Geometric Free Path of Supersonic Radiative Diffusion Wave in Concentric Shell Structrues

在局域热动平衡近似下,研究几何壳层结构所产生的腔体约束对辐射过程的影响.基于同心圆柱和同心圆球的壳夹层光输运模型,给出垂直于光子通路的谱辐射能流径向分布和平均能流公式,通过数值求解得到截面平均的壳层结构平均几何自由程,研究输运通道的径向光学厚度和几何结构对几何自由程的影响.由于球几何对光子的三维束缚,球壳层结构对辐射过程的影响比柱壳层更大,辐射过程必须根据实际几何构型和辐射通道的光学厚度予以几何自由程的修正.为方便使用,根据一定几何构型结合严格数值解给出了几何自由程的拟合公式.

With local thermodynamic equilibrium approximation, radial position-dependent energy flux for diffusive supersonic wave in low density filled cylinder or sphere shell structures with high density walls are given. We obtain arched-type distribution of geometric factor versus radius in cylinder and sphere shell structure. Mean geometric factor is obtained from cross-section average of total radiative energy flux. Effect of spherical shell structure on radiation process is much greaterr than that of cylinder structure. Geometrical free path must be considered in simulation of radiative diffusivity or thermal conductivity for sphere shell structures models. A fitted formula of geometric factor according to numerical solutions is given.