Study of the Effect of AP/HTPB Propellant Inner Hole Shapes on the Cook-off Characteristics

Abstract

To obtain the effect of inner hole shape of the propellant on the cook-off characteristics, 2D and 3D unsteady cook-off models, which were based on the Arrhenius law, were established for the solid rocket motors loaded with ammonium perchlorate/terminally hydroxylated polybutadiene(AP/HTPB). Numerical simulations of the cook-off process of solid rocket motors with round-shaped and star-shoped charge configurations were carried out in an attempt to reveal the effect of the inner hole shape on the cook-off characteristics of the propellant. The results show that the inner hole shape of the propellant has little effect on the cook-off response characteristics of the motor under fast cook-off conditions. Meanuhile, the inner hole shape of the propellant has little effect on the ignition delay time of the propellant under slow cook-off conditions but has a significant effect on the ignition temperature and ignition location. The ignition temperature of round-shaped propellant is higher than that of star-shaped hole. The ignition location of the round-shaped propellant is close to the inner wall surface of the propellant head. It gradually moves towards the end with the increase of the heating rate. While the ignition position of the star-shaped hole propellant is close to the wall of the inner hole of the middle of the propellant and changes abruptly with the increase of heating rate.