Detailed Numerical Modeling and Simulation of Fe2O3−Al Thermite Reaction

• Published in: Propellants, explosives, pyrotechnics explosives, pyrotechnics, 2021-05, Vol.46 (5), p.806-824
• Main Authors: Souza, Kesiany M., Lemos, Marcelo J. S.
• Format: Article
• Language: English
• Subjects: Activation energy; Aluminothermic Reaction; Aluminum oxide; Burning rate; Exothermic reactions; Finite difference method; Finite-Difference-Scheme; Hematite; Hematite-Aluminum Reaction; Ignition; Mathematical models; Melt temperature; Simulation; Temperature; Temperature dependence; Temperature profiles; Thermite; Thermochemical properties; Wave velocity; Wildlife conservation
• ISSN: 0721-3115; 1521-4087
• DOI: 10.1002/prep.202000290

A thermite reaction is a self‐propagating exothermic reaction with many practical applications in welding processes, material synthesis, pyrotechnic and initiator technologies. Motivated by the above‐mentioned, the present study involves modeling and simulation of common hematite‐aluminum thermite reaction with the aim of predicting temperature levels and radial burning speeds in a thin disk ignited at the center. Balance equations of species and energy conservation were solved in one dimension space by applying a finite difference method, considering no species transport and a one‐step mechanism. The Arrhenius equation was adopted to model the kinetics rate. Phase change and temperature dependence of the thermochemical properties were also considered. Analyses of spatial and temporal meshes revealed that numerical results were independent of the grid used. Predictions show that the ignition procedure affects the formation of the reaction‐front, higher temperatures, and longer ignition zones can start the self‐sustained reaction earlier. However, once the reaction wave is established, its velocity and peak temperature are the same, independent of the initial temperature profile. Simulations herein also show that an increase of the activation energy and decrease of the pre‐exponential factor slows down the reaction speed considerably, impacting on accurate prediction of reaction‐wave velocity. Further, the activation energy influences the burning velocity much more drastically than the pre‐exponential factor. The maximum temperature observed in the model is around the melting temperature of alumina (2327 K), which is in agreement with the experimental results reported in the literature.