Modeling Approach For Intumescing Charring Heatshield Materials

Intumescing heatshield materials have been shown to provide significant thermal protection for missile system environments. The design and use of these materials requires the analytic understanding of a considerable level of thermodynamic phenomena occurring on the surface as well as in-depth. These phenomena can include in-depth thermochemical decomposition, pyrolysis gas generation and mass transfer, thermophysical property change, thermochemical and mechanical ablation, intumescence or conduction path growth, and boundary-layer modification due to pyrolysis gas injection or surface reactions. The current state of the art for modeling thermochemically decomposing heatshield materials is enhanced through the addition of intumescent behavior effects to the Aerotherm Charring Material Thermal Response and Ablation Program (CMA). State-of-the-art real-time radiography methods along with embedded thermocouples were utilized in a radiant heating environment to obtain in-depth thermochemical decomposition, thermal response, and intumescence. The resulting intumescence model was applied and validated for a low-shear hypersonic high-altitude environment.