Numerical analysis on combustion of AP/HTPB sandwich propellant based on complex gas kinetics

Considering of the combustion characteristics of AP /HTPB composite solid propellant,a heat-flux coupled steady combustion numerical model of sandwich propellant based on complex gas kinetics was set up to study the flame structure and combustion characteristic of composite solid propellant.A complex gas kinetics composed of 49-species and 328-reactions was proposed to model flame,a one-step condensed total kinetics was used to determine initial gas species and heat release,an equivalent source term method and gas/solid heat-flux coupled condition was applied to represent gas phase mass-addition process of burning surface.The computational results show that,at lower pressure,total flame behaved as pre-mixed structure,as pressure increased,a high temperature diffusion flame zone was formed along AP/HTPB material surface,and the leading-edge flame became closer to burning surface,while flame blend point got farer.The computational burning rate pressure index was about 0.326 ~ 0.683,and the variation of burning rate with pressure,when binder width was about 100 ~ 176 μm,was consistent with experimental burning rate and computational burning rate of Knott's computational burning rate.