| Both steady-state modeling and unsteady-state modeling of solid monopropellant combustion have advanced to a higher level since detailed gas phase kinetics has become available. In this research, steady state combustion of HMX (cyclotetramethylenetrinitramine, C4H8N8O8) and AP (ammonium perchlorate, NH4ClO4) combustion has been investigated with detailed elementary gas phase reaction steps, and reasonable results have been obtained compared to previous modeling work and experimental data. In addition, unsteady-state combustion of HMX has been studied for pressure-driven response and fast cookoff processes, and new insights have been discovered. There are four major parts of this research. First, the influence of condensed-phase decomposition mechanism on HMX temperature sensitivity (the ratio of the change of the burning rate to the change of the initial temperature at constant pressure) was studied. Modeling shows that the liquid decomposition mechanism, reflected by the ratio of N2O/NO2 leaving the burning surface, probably plays a dominant role in determining temperature sensitivity. Second, the HMX pressure response (the ratio of the maximum change of the burning rate to the pressure oscillation) was modeled, including the effect of condensed phase void fraction. The research found that the void fraction close to the surface has a great influence on the response. Third, an HMX 1-D fast cookoff model was developed based on whether the initial decomposition products remain within the crystal lattice or escape into a fixed closed space. The two cases turned out to be the two extremes in calculating fast cookoff time. Fourth, the steady-state combustion of AP was modeled with an assumption of solid-phase decomposition, which was observed in experiments. Including solid-phase decomposition showed significantly improved comparison with experimental data. Each part is described separately in Chapters 4, 5, 6 and 7. |
