Detailed Reaction Kinetics Modeling and Simulation of the Combustion of AP/HTPB Solid Propellant Using the Subregional Progression Method

To investigate the detailed multiphase combustion process of solid propellant, especially the complex physicochemical processes that occur in the condensed-phase region, a comprehensive numerical-analysis method is developed in this study. A rigorous and complete mathematical model of solid-propellant combustion is established. The mathematical model of a solid propellant is divided into three phases. The solid-phase region determines the reaction initiation conditions, the condensed-phase region is calculated using an independently compiled subregion progression method, and the gas-phase region is simulated using Chemkin software. The condensed-phase calculations are coupled with the gas-phase calculations to ensure the accuracy of the results, and the phases are coordinate-transformed to enable a fixed-interface representation of the different phases. The combustion process of AP propellant was simulated using this model, and the calculations are in good agreement with the experimental data. The present model was compared with previous models for NH3 and NO2 with more accurate calculations and supplemented with NO calculations. The combustion temperature and species distribution of AP/HTPB propellant were calculated, and the combustion of the nitrogen species in the propellant occurs after the combustion of the carbon species. The temperature sensitivity variations of the elementary kinetics reactions were analyzed, and the key elementary reaction R45 (H+O2=O+OH) and R33 (CH3+H(+M)=CH4(+M)) influencing the propellant combustion temperature were obtained. Finally, AP/HTPB propellant combustion with different ratios was simulated to explore the species evolution in the combustion region.