Numerical modeling for the combustion of simulated solid rocket motor propellant

The numerical procedure for the burning of Ammonium Perchlorate (AP) with a Fuel-Binder (Hydroxyl Terminated Polybutadience HTPB) heterogeneous propellant is presented. This model accounts for the two-step reaction mechanism for the primary diffusion flame at the interface between Binder (B) and the oxidizer AP and the AP premixed flame. The complete coupling between the gas-phase, the condensed-phase, and the unsteady non-uniform regression of the propellant surface is considered. The parameters used in this model are chosen to fit experimental data for the burning of the composite AP/Binder. The propagation of the unsteady non-planer regression surface is described, using the Essentially-Non-Oscillatory (ENO) scheme with the aid of the level set strategy. The Alternating-Direction-Implicit (ADI) solver is employed to solve the full Navier-Stokes equations in the gas phase for the variable density model. The results show the effect of various parameters on the surface propagation speed, flame structure, and the burning surface geometry. A comparison between the computational and experimental results is presented.