COKE - A model of heat and mass transfer in a pyrolyzable composite material

A heat and mass transfer model, COKE, is defined for detailed descriptions of the physico-chemical processes in a composite material exposed to an intense flow of superhot gases such as experienced by reentry vehicles. The material is composed of reinforcing fibers embedded in an organic resin matrix, e.g., a phenolic resin, which pyrolyzes at temperatures from 2000-3000 C. The situation is modeled in terms of three zones: virgin material below 350 C, where heat is transferred by conduction; second zone where pyrolysis begins and strong thermal blocking occurs; and a third zone where the material is cokefied and reactions with pyrolytic carbon dominate. Governing equations are defined for the conservation of energy, atomic species, continuity, the gasdynamic state and motion. The rate of gas production is quantified, along with the reaction kinetics. Sample results are provided for an application of COKE for a silica-fiber reinforced phenolic resin undergoing hot gas flow pyrolysis.