Flame Dynamics of AP/HTPB Composite Propellant in Unsteady Rocket Motor Based on Multilayer Sandwich Model

The flame dynamics of ammonium perchlorate/hydroxyl-terminated polybutadiene (AP/HTPB) composite propellant subject to the acoustic oscillations in solid rocket motors (SRMs) is numerically investigated in this article. A multilayer sandwich model is established to provide the flame with a combustion environment that can interact with the flame. The effect of the HTPB segment size is analyzed as well. The results indicate the mass transfer processes could occur between the flame and combustion environment and increase the reactant concentrations of the final flame. Thus, the average temperature of the final flame is higher. The temperature fluctuation of the final flame is greatly reduced as well. The HTPB segment size has a different effect on the near-burning surface flame and final flame. The wider HTPB segment thickness can result in a higher temperature of the near-burning surface flame because more gaseous pyrolysis products of HTPB are provided. However, larger HTPB segment size can reduce the final flame temperature because the impact of the environment has been weakened.