Experimental and modeling studies of two-dimensional ammonium perchlorate diffusion flames

We investigated two-dimensional axisymmetric diffusion flames in which the surface decomposition products of ammonium perchlorate (AP) combustion provided the coflow for a methane fuel stream. The two-dimensional problem was solved using the fully elliptic formulation of the governing equations. By utilizing recent developments in hydrocarbon, chlorine, NO_x, and AP kinetics, we formulated a detailed transport, finite rate chemistry system for the temperature, velocities, vorticity, and species mass fractions of the combined flame system. We compared the results of this model with a series of experimental measurements in which the temperature was measured with OH rotational population distribution, and the transient species OH, CN, and NH were measured with planar laser-induced fluorescence and emission spectroscopy. The kinetic mechanism, previously validated in one-dimensional experiments, was found to give good results in the two-dimensional model when compared with the experiments. The two-dimensional model can be used to understand the effects of solid propellant heterogeneity on combustion zone microstructure and the location and structure of heat release zones that control the propellant ballistic properties. It is a first step in developing computer codes that can a priori predict propellant ballistic behavior via modeling, thereby partially supplanting expensive physical formulation and testing.