Interactions between turbulent flow and diffusion flame of composite propellant in a solid rocket motor with sidewall mass injection

The numerical procedure for a diffusion flame based on Ammonium Perchlorate/Hydroxyl-Terminated Polybutadiene (AP/HTPB) composite propellant in a solid rocket motor (SRM) is presented. This article accounts for the turbulence effects in a combustion chamber with sidewall mass injection and the propellant diffusion flames at various axial locations are studied. The mutual coupling between the vortical and entropy modes is discussed comprehensively, with the inclusion of the influence of the chamber pressure. The effects of the AP particle size and the combustion environment are also analyzed. The flow evolution in the SRM is clearly observed in the results: laminar, transitional, and turbulent. Compared with the laminar area, the flames fluctuate drastically in the turbulent flow, and the chemical kinetics processes are altered greatly. The diffusion and mixing processes of the reactants are enhanced due to the contribution of the turbulence, and the heat release of the flames is elevated. The high chamber pressure and smaller AP size could lead to more intensive fluctuations of the flame heat release. This may drive thermoacoustic instability in the SRM.