Research Of The Effect Of Thermal Stimulation Intensity On Cook-off Characteristics Of Explosives

When expensive large-scale combat platforms such as aircraft carrier or carrier-based aircraft are exposed to accidental fires, the ammunition will be heated to response temperature in different ways with the changing of ammunition location. In order to reduce the accidents and damage caused by accidents, the effect of thermal stimulation intensity on cook-off characteristics of explosives is studied in the condition of directly being heated to response temperature or being heated to a certain temperature and kept for a long time.Firstly, thermal analysis tests of JH-95 explosives and JB explosive are conducted applying differential scanning calorimetry. In addition, the pre-exponential factor and activation energy of two kinds of explosives are calculated with Kissinger method, which provides a basis for the selection of parameters in the following section of numerical simulation.Secondly, slow cook-off tests about JH-95 explosives and JB explosives were carried out at the thermal stimulation intensity of 1℃/min and 2℃/min respectively with self-designed cook-off experiment setup. The thermal response characteristics of explosives is studied in different thermal stimulation intensity. In addition, cook-off experiments of JH-95 explosives and JB explosives with constant time of 50 min were carried out under different temperature at the the thermal stimulation intensity of 1℃/min. The thermal response characteristics of explosive is studied in this conditions. Research results show that thermal stimulation intensity has an influence on slow cook-off response characteristics of explosives. The ambient temperature of response moment gradually decreases with the declining of thermal stimulation intensity. However, the response intense is more violent with the declining of thermal stimulation intensity. When cook-off sample is heated to a certain temperature and kept for a long time, there is a lowest constant temperatureminT which can make explosives be ignited. This temperatureminT is called thermal initiation critical temperature. It’s found that explosives is more dangerous when cook-off sample is heated to a certain temperatureand kept for a long time, the ambient temperature of reaction is lower and the response intense is more violent.Based on the above studies, numerical simulation is conducted applying Fluent software to study the response ambient temperature of explosive mentioned above in different thermal stimulation intensity. In addition, numerical simulation in changing thermal intensity is carried out to study the two kinds of explosives’ thermal initiation critical temperature and the relationship between thermal initiation temperature and thermal stimulation intensity. Results show that the ambient temperature of response moment decreases gradually with the drooping of thermal stimulation intensity. However when the thermal stimulation intensity is lower than3.3℃/h, the ambient temperature of response moment basically tends to a certain value.What’s more, thermal stimulation intensity affects the position of the ignition. With the declining of thermal stimulation intensity, the ignition position moves gradually from the edges and corners of explosives grain to the inside of explosives grain, finally to the geometric center of the explosives grain. Since then the ignition position will not change anymore.When cook-off sample is heated to a certain temperature and kept for a long time. The thermal initiation critical temperature of explosive increases gradually with the improving of thermal stimulation intensity. When thermal stimulation intensity increases a certain extent,thermal initiation critical temperature will not change again with the increasing of thermal stimulation intensity. In addition, the thermal stimulation intensity in heating stage has no influence on the ignition position which is always in the center of explosives grain.