To investigate the micro-scale combustion characteristics of composite propellants, a two-dimensional BDP micro-scale model for ammonium perchlorate/hydroxyl-terminated polybutadiene (AP/HTPB) was developed. Numerical simulations were conducted to evaluate how AP particle size and mass fraction influence the diffusion behavior, flame structure, and gas-phase temperature distribution. The results indicate that increasing the AP particle size significantly enhances the overall diffusion characteristics, which gradually become the dominant factor in the combustion process. Specifically, the flame exhibits more pronounced diffusion features, and the temperature distribution near the burning surface becomes increasingly non-uniform. Furthermore, as AP particle size increases, each gaseous component demonstrates greater diffusion tendencies, requiring a thicker mixing layer to achieve complete homogenization. Regarding the AP mass fraction, its increase strengthens the thermal feedback from the gas phase to the solid phase, leading to a slight rise in the burning surface temperature. While the diffusion characteristics of AP-derived macromolecules remain relatively stable, the concentration of residual oxygen increases with higher AP mass fractions.
Liu et al. (Wed,) studied this question.