This document details original numerical studies performed by the author pertaining to solid propellant combustion. Detailed kinetic mechanisms have been utilized to model the combustion of the pseudo-propellants RDX/GAP and AP/HTPB. A particle packing model and a diffusion flame model have been utilized to develop a burning rate and an aluminum agglomeration model. The numerical model for RDX/GAP combustion utilizes a "universal" gas-phase kinetic mechanism previously applied to combustion models of several monopropellants and pseudo-propellants. The kinetic mechanism consists of 83 species and 530 reactions. Numerical results using this mechanism provide excellent agreement with RDX and GAP burning rate data, and agree qualitatively with RDX/GAP pseudo-propellant data. The numerical model for AP/HTPB combustion utilizes the same universal mechanism, with chlorine reactions added for modeling AP combustion. Including chlorine, there are 106 species and 611 reactions. Global condensed-phase reactions have been developed for six AP percentages between 59% and 80% AP. The AP/HTPB model accurately predicts burning rates, as well as temperature and species profiles. The numerical burning rate model utilizes a three-dimensional particle-packing model to generate cylindrical particle packs. Particle-size distributions have been modeled using a three-parameter lognormal distribution function. Pressure-dependent homogenization has been used to capture pressure effects and reduce cpu time. A "characteristic" burning path is found through each particle pack. Numerical results showed that different path-finding approaches work better depending on the propellant formulation and combustion conditions. Proposed future work and modifications to the present model are suggested. The numerical agglomeration model utilizes the same particle packing model and particle-size distribution function as in the burning rate model. Three preliminary models have been developed examining the ideas of pockets, separation distance, and aluminum ignition. Preliminary model results indicate the importance of predicting aluminum particle ignition. In the final model, the surface is regressed numerically through each particle pack. At each surface location, calculations are performed to determine whether aluminum particles combine and/or ignite. Ignition criteria have been developed from the results of the diffusion flame model and an analysis of particle-pack cross-sections. Numerical results show qualitative agreement with each experimentally observed trend. Proposed future work and modifications to the present model are suggested.



College and Department

Ira A. Fulton College of Engineering and Technology; Chemical Engineering



Date Submitted


Document Type





propellant, combustion, model, modeling, numerical, computer, burning rate, aluminum, agglomeration, RDX, GAP, AP, HTPB