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High-fidelity charring ablator thermal response model

par Mansour, Nagi N.N.;Lachaud, Jean;Magin, Thierry ;De Mûelenaere, Julien;Chen, Y. K.
Référence 42nd AIAA Thermophysics Conference(42: 2011-06-27), American Institute of Aeronautics and Astronautics
Publication Publié, 2011

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Résumé :

Low-density carbon/phenolic is a class of ablative materials that is attractive for space exploration missions that use blunt bodies where weight and performance of the material are of primary importance, but shape preservation is not critical. We consider a relatively simple class, PICA, that consists of carbon fibers impregnated with phenolic as the matrix. A new formulation for models of the response of this class of materials to high-enthalpy environments is summarized. The new formulation consists of conservation equations for species, mass, and energy in porous media. The velocity is obtained using Darcy's law with the pressure obtained so that mass is conserved. Pyrolysis of the matrix is modeled using a discrete number of progress variables representing the decomposition reaction stages. Each decomposition reaction produces its own set of species. The one-dimensional equations are solved by discretizing in space using a second-order staggered mesh on a moving grid, and an implicit dual time step scheme is used to advance the solution in time. The Charring Ablator Thermal response (CAT) code that implements the formulation is tightly coupled to a chemistry code that enables handling equilibrium as well as finite rate chemistry. It was thoroughly verified against analytical solutions and comparisons of results to results using different numerical methods and techniques. Sample verification cases are summarized showing excellent accuracy. Sample material response cases are presented showing the capability of the code. We have established that models of this type of ablative materials are highly sensitive to the energy and chemistry balance at the gas surface interface and that these balances are significantly related to material performance. Unfortunately, highquality data for the decomposition of phenolic is missing and is needed to enable validation of the formulation.