| The weakest link in combustion simulation of energetic materials is the kinetics of condensed-phase reactions, which has been treated empirically in most simulations. The goal of this thesis is to obtain thermal decomposition kinetics of condensed phase 1,3,5,7 tetranitro-1,3,5,7-tetrazocine (HMX), and investigate methods for incorporating the kinetics into combustion simulation.; Both kinetic model-fitting and isoconversional analysis are used to determine the kinetics of HMX thermal decomposition. The activation energy estimated with model-fitting method is 167 +/- 4 kJ/mol from isothermal decomposition of solid and liquid HMX, and 146 +/- 4 kJ/mol from nonisothermal decomposition of solid HMX. The activation energy obtained with the isoconversional analysis is a function of the extent of decomposition, suggesting a multistep/channel mechanism.; An analytic steady-state HMX combustion model is developed based on the WSB model. It was found that the effect of the activation energy and heat release of condensed-phase reaction is significant. A low value of the activation energy (146 kJ/mol) fits the experimental data better than higher activation energies. The use of different kinetic models makes more difference in conditions where the surface temperature is low and no external radiation applied, in which the contribution from condensed-phase reaction is comparable to other sources. The power law model seems to be the best kinetic model to predict QSHOD linear burn rate responses to oscillatory pressure and laser radiation.; A numeric ignition/unsteady combustion model using finite difference method is also built. Results from the two combustion models agree with each other reasonably well.; This thesis begins with a literature study of the kinetics and mechanisms of HMX thermal decomposition (Chapter 1), existing model-fitting and isoconversional methods of thermal analysis (Chapter 2), and the theories in HMX combustion simulation (Chapter 3). Chapters 4 and 5 give the results of the kinetic analysis of the thermal decomposition of HMX monopropellant and two composite propellants, respectively. Chapter 6 describes the new method of applying isoconversional method to study the kinetics of HMX combustion . Chapters 7 and 8 present the efforts of incorporating complex condensed phase kinetics into steady state, quasi steady and unsteady combustion simulations. Finally, chapter 9 concludes the dissertation and suggests some future directions. |
