Simulation Study On Thermal Safety Of Red Pyrotechnic Composition

The accidents of pyrotechnic composition occur frequently,and have caused huge casualties and property loss during its processing,transportation storage,and use.The influence factors and laws of thermal safety of pyrotechnics composition have become a hot issue in the research area.Based on the summary of the methods and the research status for evaluating thermal safety of energetic materials on pyrotechnic composition,the two-dimensional models of naked grain and paper packing grain are established by ANSYS software.It will calculate the self-accelerating decomposition temperature,ignition delay period and ignition position of the pyrotechnic composition under different environmental temperature,packing scale and packing condition.The pyrolysis process of red pyrotechnic composition under different ambient temperatures is simulated and the self-accelerating decomposition temperature of the pyrotechnic composition is determined to be 631 K and the ignition temperature is 670 K,which is in good agreement with the experimental results in the literature.The influence of ambient temperatures on the thermal decomposition process of pyrotechnic composition is investigated.When the ambient temperature is lower than the self-accelerating decomposition temperature,the thermal decomposition does not occur;when the ambient temperature is higher than the self-accelerating decomposition temperature,the thermal spontaneous combustion occurs.As the ambient temperature increases,the ignition delay period is shortened and the ignition position is shifted upward.When the ambient temperature raises at a certain rate of heating,the ignition time of the pyrotechnic composition decreases as the heating rate increases.It is found that when the shape of the grain are in the same aspect ratios,but different scales,the self-accelerating decomposition temperature and the ignition position decrease with the increase of the volume,and the ignition time is shortened.When the diameter of the pyrotechnic composition is constant and the height is increasing,the self-accelerating decomposition temperature and the ignition position are reduced.The effects of packaging conditions on the thermal safety of pyrotechnic compositions are also studied.With the increase of the thermal conductivity of the packaging material,the self-accelerating decomposition temperature rises,and he thermal safety is better.When low thermal conductivity material packages the pyrotechnic composition,the thicker the package is,the lower the self-accelerating decomposition temperature of the pyrotechnic composition is,and the worse the thermal safety is.When high thermal conductivity material packages the pyrotechnic composition,the thicker the package,the better thermal safety.The study shows that during the storage of pyrotechnic composition,the scale of accumulation should be controlled strictly,and the environment temperature monitoring and alarming system should be established.To prevent fire and explosion accident of pyrotechnic composition,setting an appropriate limit in the system is crucial.The applicable package material is also vital in the thermal safety of pyrotechnic compostion.