Numerical analysis of fast cook-off and case failure characteristics of solid rocket motor with AP/HTPE star-charged

To investigate the cook-off response and heat transfer in AP (ammonium perchlorate)/HTPE (hydroxyl-terminated polyether) solid rocket motor (SRM) under fast cook-off conditions (FCC), a three-dimensional numerical model based on the BDP (Becksted-Derr-Price), chemical-thermal decomposition scheme was developed. This model incorporates propellant ignition and combustion reactions. The study conducted numerical simulations under FCC with heating rates of 1.6 K/s to 2.4 K/s. the grid-node separation method was used to effectively characterize the motor casing's dynamic response during large deformations. Results show that ignition occurs in the propellant's bottom annular region, with multiple hot spots forming simultaneously. The ignition delay time is linearly related to the heating rate, and varying heating rates did not significantly affect ignition temperature. Post-ignition, combustion pressure caused limited casing damage, with no detonation. The motor case remained largely intact, though severe deformation and fragmentation occurred near the ignition site, accompanied by longitudinal cracks.