Identification of radiative properties of a reticulated porous

摘要

Many engineering applications where porous sponges are employed involve in high operating temperature. In order to accurately calculate or to predict the heat transfer by the porous sponge requires a good knowledge about their radiative properties. To identify the radiative properties, the sponge as a whole can be considered as a lump of homogeneous media with radiative properties defined in a similar fashion as that of a homogeneous participating fluid media. Hendricks used the experimental hemispherical reflectance and transmittance measurements along with inverse analysis techniques based upon discrete ordinates radiative models to obtain the radiative properties of the reticulated porous ceramic sponges. Tancrez et al. developed a theoretical ray tracing approach to identify the extinction coefficient and scattering phase function for a porous media of known structural morphology. This method was used by Petrasch et al. to identify the radiative properties of a reticulated porous Alumina sponge for which the structural data was obtained from CT scan of the real sponge. In this study we used a in-house ray tracing code to identify the radiative properties of a SiSiC sponge with the theoretical back ground given in [3], [4]. The structural data for the study is obtained from μ-CT scan of the real SiSiC sponge structure with a resolution of 40μm per voxel in each spatial direction. Using these μ-CT scanned images the grid data required for our in-house ray tracing code is generated using ANSYS software. The study involves in considering the sponge structure as a continuous media with extinction coefficient and scattering phase function defined in a manner as they are defined for a participating fluid media. The space occupied in between the stolid structures of the sponge media is assumed to be radiatively transparent and the solid strut materials are considered opaque which absorb some of the incident radiation and scatter the remaining. The sponge structure is assumed homogeneous and is tested for statistical structural isotropy.