Effects of Thermal and Chemical Nonequilibrium on Response of Charring Ablative Materials

A material response solver that predicts the response of charring ablative materials under different degrees of physical modeling complexity is developed. The solver provides a versatile environment for engineering analyses and incorporates a third-party library for the evaluation of thermodynamic/transport properties of pyrolysis gas mixture and chemical kinetics, if necessary. Thermal nonequilibrium between the solid and the gas phases is considered using the two-equation model. A novel reactor network approach is used for modeling pyrolysis gas flow inside the porous ablative material, allowing simulations with various gas compositions and reaction mechanisms. Effects of chemical and thermal nonequilibrium and influences of the porosity and permeability of the porous structure on the response of charring ablative materials are explored. It is observed that higher porosity and smaller permeability values induce local thermal equilibrium, and chemical reactions increase the temperature differences between the phases.