Numerical computing of heat safety of TNT in cook-off test

In order to study the thermal reaction principles of explosives with different sizes and at different heating rates, this paper builds a cook-off test model of explosives. In this model, we use the Arrhenius equation to describe autothermal reaction of explosives, consider the endothermic phase transition and the change of heat conductivity at different kinds of state of TNT, use the finite difference method to discretize the model and make program to solve it. We calculate the process of the cook-off test at the same heating rate but with different sizes and with the same size but at different heating rates. The results show that the ignition temperature almost keeps unchanged with different sizes of TNT. As the size of TNT increases, the ignition position moves outward from the shaft of cylindrical model. However, the heating rate has a great influence on the ignition time and position. When heating rate rises, the ignition time shortens, the ignition position moves forward to the edge, the temperature distribution becomes more uneven and the time for phase transition with the different distance to the shaft is greatly affected. When the heating rate is 1K/s, the TNT in the center of the model has not had phase transition when whole explosive explodes. Heating rate has little effect on the ignition temperature while the ambient temperature has positive relation with heating rate when explosive ignites.