NUMERICAL ANALYSIS OF EXPLOSIVE SOLIDIFICATION UNDER THE EFFECT OF DIFFERENT BOUNDARY CONDITIONS

Casting of explosives in a shaped charge shell for the production of warheads and antitank ammunitions is an important process. This type of device has a conical void coated by a metal liner, which promotes a high velocity jet of the liquid metal after the detonation of the explosive. Distinct explosives are employed with this purpose and an investigation of the cooling conditions is suitable. Therefore, the objective of this work is to evaluate numerically the solidification process of TNT, Baratol and Composition B explosives inside a shaped charge by utilizing the apparent heat capacity method on a transient-diffusive heat transfer equation to model the phase change. The mathematical model is solved in COMSOL Multiphysics and Modeling Software by a finite-element approach. The solutions are verified against literature ones. Prescribed temperatures are considered for conical and bottom surfaces, while natural convection is applied for the outer surfaces. Three boundary conditions for top surface, namely convection, adiabatic and isothermal boundary conditions are analyzed in the simulations. Results show that, for the same analyzed geometry, Baratol has solidified in less time than TNT and Composition B. It has been concluded that the most sensitive parameters of this process are the thermophysical properties of the explosive. Finally, the isothermal top boundary condition showed to be preferable to promote solidification of high explosives in shaped charge shell.