NEW RADIATIVE ANALYSIS APPROACH FOR RETICULATED POROUS CERAMICS USINGDISCRETE ORDINATES METHOD

A novel radiative modeling technique using discrete ordinates has been developed for reticulated porous ceramics (RPCs) from experimental me asurements of transmittance and reflectance on small samples of partia lly stabilized zirconium oxide (PS ZrO2) and oxide-bonded silicon carb ide (OB SiC). The new technique defines and quantifies the direct tran smittance fraction, f(dt), of a reticulated porous ceramic, demonstrat es how it redefines the extinction process, and creates a new effectiv e extinction coefficient, K-lambda,K-eff. This ultimately produces a m odified form of the radiative transfer equation (RTE) and an innovativ e discrete ordinates formulation to solve the RTE unique to RPCs. The direct transmittance modeling approach has been compared to a more con ventional homogeneous modeling approach, in which the direct transmitt ance effects are essentially ignored and the RPC is treated as a homog eneous lump of material. The two modeling approaches yield identical r esults in predicting small rest sample reflectances and transmittances . The direct transmittance technique does demonstrate explicitly, thro ugh a unique relationship between absorption coefficients in the two m odeling approaches, the importance of scattering processes in enhancin g the absorption mechanism in RPCs. It cart also be apr important seco ndary modeling technique that imposes additional parameter constraints in an inverse analysis to help refine derived radiative coefficients.