Numerical Study of PBX 9501 Explosive Combustion Process in Confined Space

Abstract

Explosives combustion is primarily classified into conductive and convective combustion. In situations where confinement is sufficiently strong, the instantaneous high pressure generated by convective combustion in cracks can cause rapid fragmentation of the explosive matrix, resulting in a significant increase in the combustion surface area and triggering a high-intensity reaction with potentially catastrophic consequences. Therefore, the study of convective combustion in cracks is crucial for ensuring the safety of weapons and explosives. Previous simulation studies have primarily used finite element analysis software, which has excellent performance in handling explosive detonation processes. However, its accuracy in describing gas behavior between explosives and constrained containers is limited. This study divides the combustion process of a pre-cracked explosive in a confined space into four stages based on reasonable assumptions and simplifications. We developed a simulation method that combines the Arrhenius formula with the MWSD model to model the combustion rate of the explosive. By introducing a correction coefficient, Con, to the Arrhenius formula, the formula and MWSD model control the first and third stages of explosive combustion, respectively, while smoothly transitioning during the second stage. We used this method to numerically simulate the experimental results of Shang Hailin et al. on a crack width of 50 μm. The simulation results include the temperature field and pressure field of the first three stages of explosive combustion and the pressure rise curve of the pressure measurement point at the same location, as in the experiment. The simulation results are consistent with the experimental results.