Numerical study of cook-off temperature and ignition dynamics in high-energetic materials

This study presents an approach for predicting temperatures and ignition time during the cook-off process of solid propellants, with a focus on identifying potential hot spots and conduction losses. A pool fire temperature model is introduced to enhance the understanding of the thermal stability of solid propellants, specifically ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB). Numerical simulations were performed to analyze the thermal behavior of the AP/HTPB propellant under cook-off conditions using a three-dimensional, transient model with heating rates between 0.67 and 0.8 K/s. The ignition temperatures for the AP/HTPB propellant varied with distance and time, recorded at 641.40 K, 598.10 K, and 554.43 K. To streamline the computations, a simplified model with hot wall conditions for the outer steel wall of the propellant was adopted, accurately replicating the cook-off processes under specific experimental conditions and aligning closely with experimental findings. The similarity between the model predictions and experimental data provides a reliable means of assessing the explosion risk of AP/HTPB in cook-off scenarios, with relative errors of 0.845% and 2.03% for ignition temperature and ignition delay time, respectively. Additionally, the data generated from this model can aid in developing safety protocols for plant design, establishing safety zones, and planning emergency evacuation routes to mitigate potential hazards.