Abstract
A procedure is established to digitize a three dimensional structure within a carbon foam using a commercially available X-ray Computed Tomography (CT). The digitized model will be used to evaluate radiative transport coefficients such as absorption and scattering coefficients of the carbon foam. The obtained radiative transport coefficients will be used to calculate radiative transfer in the porous material, which is believed to strongly affect a thermal protective performance of an atmospheric entry vehicle. For the first step to achieve the objectives of the present study, X-ray images are obtained by using a micro-focus X-ray CT system(Shimadzu, SMX-100CT), and the validity of the 3-dimensional digitized model so obtained is discussed. In the present study, whether a representative elementary volume (REV) is taken or not within the digitized model is examined. It should be noted that the REV represents a minimum size of the digitized model within which a macroscopic nature of a material such as porosity can be replicated. The results show that even though a carbon-based material is known to be difficult to model a three-dimensional sturucture by using a X-ray CT due to its low absorptivity against X-ray beams, we can successfully reproduce the macroscopic porosity value of about 90% by using a digitized model larger than REV.
