Modeling of RDX/GAP/BTTN pseudo-propellant combustion

A comprehensive numerical analysis has been developed to predict the burning characteristics and detailed combustion wave structure of RDX/GAP/BTTN pseudo-propellant over a broad range of pressures. The present work extends an existing model for the steady-state combustion of RDX/GAP pseudo-propellant to include the salient features of BTTN, a commonly used plasticizer for practical solid propellants. The entire combustion zone is divided into the solid-phase, subsurface multiphase, and gas-phase regions. In the solid-phase region, the constituent ingredients are physically linked together and heated by conduction. Five global decomposition reactions, as well as subsequent reactions of RDX, GAP, and BTTN, are considered in the near-surface multiphase region. The overall gas-phase kinetics considers 72 species and 429 reactions in describing the heat-release mechanism. Good agreement is obtained with measured burning rates in the pressure range of 1–100 atm. The propellant surface temperature matches closely with the measured value and depends strongly on the RDX evaporation. The burning rate of RDX/GAP/BTTN is in general higher than that of RDX/GAP, a phenomenon that may be attributed to the stoichiometrically balanced nature of BTTN.