A two-dimensional model has been developed to study the flame structureabove composite propellants utilizing a vorticity-velocity formulation of thetransport equations. This formulation allows for a more stable, robust,accurate, and faster solution method compared to the compressible Navier-Stokesformulations of the equations for low Mach flow. The model includesmass and energy coupling between the condensed and gas phases. Thecondensed-phase model is based on previously reported one-dimensionalmodels and includes distributed decomposition and multi-step reactionkinetics. The model uses a detailed gas-phase kinetic mechanism consisting of37 species and 127 reactions. The kinetic mechanism and species diffusiondetermine the flame structure of the system; no assumptions are made beforehand aside from appropriate boundary conditions. Numerical studies havebeen performed to examine the flame structure above an AP particlesurrounded by a homogenized AP/HTPB binder. The calculated flamestructure was found to be qualitatively similar to the BDP model with bothpremixed and diffusion flames present. Results present significant insight intoAP's ability to control a propellant's burning rate and illustrate the importanceof the primary diffusion flame.
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