Numerical modeling of endothermic pyrolysis and ignition delay of composite materials exposed to an external radiant heat flux

摘要: A numerical model is developed to predict endothermic pyrolysis and piloted ignition delay of solid composite materials exposed an external radiant heat flux. The considers the coupled thermochemical processes that take place in condensed phase therefore describes combustible only under conditions fast chemical kinetics gas phase. considered include oxidative thermal pyrolysis, change, radiation absorption, mass transfer a multiphase multicomposition medium. Ignition occur when critical pyrolysate flow reached at surface. implication material subjected attainment minimum concentration fuel gaseous mixture adjacent pilot (lean flammability limit). predicted over wide range fluxes for polypropylene/fiberglass with varied composition thickness. results agree well available experimental data show flux depend on material, increasing as fiber content increased. From it possible identify fiberglass required prevent given flux, result could provide guidelines toward development fire-safe composites. Finally, based delay, three categories thickness: thermally thin, transition, thick, each representing distinct delay.