Radiative Transfer in a Low-Density Ablative Material Under Arcjet Flow Conditions

Highly porous carbon-based materials, referred to as 120, 150, and 270 kg/m(3) materials hereafter, are heated in nitrogen arcjet conditions; and their respective thermal responses are analyzed both experimentally and numerically. Experiments are conducted in a 1 MW constrictor-type arcjet wind tunnel. A coupling method is used to account for the heating processes between the arcjet flow and material thermal responses. Modeling of radiative transfer in each of the test materials is done using effective radiative conductivity and evaluated using their respective optical radiative extinction coefficients. These extinction coefficients are evaluated from ray tracing calculations using X-ray computed tomography models for each material. A comparison of the results suggests that acceptable agreement between calculated and measured in-depth temperature distributions is possible with the inclusion of radiative heat transfer in the calculations.