Random packs and their use in modeling heterogeneous solid propellant combustion

It is shown that random packs of spheres of various sizes can be constructe d that model ammonium-perchloratein-binder propellants in the sense that bo th the size distributions and the packing fractions of industrial propellan t packs can be matched, Strategies for dealing with fractional numbers of l arge particles are addressed, as are strategies for dealing with a large nu mber of very fine particles (fine powder), Fine powder is necessary in a th ree-dimensional pack to achieve the required stoichiometric ratio of ammoni um perchlorate to fuel binder, but is not necessary in a two-dimensional (d isk) pack, Some preliminary calculations of the two-dimensional combustion field supported by a disk pack are presented, in which full coupling betwee n the gas phase, the condensed phase, and the retreating nonplanar propella nt surface is accounted for.