As the core fuel of solid rocket motors, the combustion response of AP/HTPB (ammonium perchlorate/hydroxyl-terminated polybutadiene) solid propellants significantly influence the design parameters and stability evaluation of the motors. This study employs a sandwich propellant model, considering the coupling of gas–solid heat transfer and the internal flow field environment of the chamber, thereby more accurately simulating the flame response environment of a real solid rocket motor. The work introduces steep-fronted waves composed of multiple acoustic modes and investigates the flame response characteristics under these conditions. Subsequently, noise is introduced to examine its effect on propellant combustion. The results indicate that, compared with single-frequency simple harmonic waves, the AP/HTPB primary diffusion flame exhibits a distinct response pattern to steep-fronted waves. Additionally, the introduction of noise intensifies the recession of the HTPB burning surface. This suggests that steep-fronted waveform and noise enhance the mixing of reactants. However, the AP premixed flame is less affected by steep-fronted waveform and noise. This study not only highlights the necessity of incorporating steep-fronted waves and noise in the numerical analysis of solid propellants but also offers a novel perspective for the in-depth investigation of combustion instability mechanisms in solid rocket motors.
Xu et al. (Fri,) studied this question.