Study On Simulation Of Cook-off Experiments And Thermal Characteristics Of RBOL-2 Explosive

Cook off test is an important method to test and evalua the sensitivity and thermal stability for high explosives。By controlling the ambient temperature of cook off bomb,researcher can observe the response of explosives in the changing thermal stimulation,but experimental method can not observe the details of a series of changes happned in the explosives when it is being heated.So cook off simulation as a supplementary measure is widely used in the research of explosives thermal safty.In this paper,single-step segmentation reaction model was established to describe HMX/DNAN/Al three components explorsive based on Frank-Kamenetskii single step zero order chemical reaction model.In this model,the calculation of thermal reaction of DNAN was described by F-K model.Aiming at the thermal decomposition of multistep reaction of HMX,this paper uses subdivision thinking to discretize the continuous process,and describes the process through the combination equations in different stages of multi-step reaction,and establish the corresponding model equations.For the multiple parameters that are unkown in the equation,this paper simulate the model by commercial software FLUENT and used the orthogonal experiment to determine the best combination of parameters.For Al(aluminum),it is regarded as a constant endothermic term in the thermal decomposition reaction of explosives.Dimension analysis is used to study the form of its endothermic equation.And its model parameters are determined by simulating according to the relevant data.The thermal reaction characteristics of RBOL-2(HMX / DNAN / AL 40% / 30%/ 30%)were investigated by single step segmentation reaction model,and the factors affecting the critical ambient temperature were explored.The bake bomb models with different aspect ratios were established.The models were heated with the same heating rate(1 K / min)to different ambient temperatures and stabilized,and the response characteristics were observed.Through the simulation results,the author found that as the aspect ratio increased,The ambient temperature also increased,and the sensitivity and thermal stability for high explosives is better.However,the increasing of thermal stability is not unlimited and eventually approaches a certain temperature value.The effect of heating rate on its critical ambient temperature is also studied.In this paper,different heating rate 1K / s,3K / min and 10 K / min were used to heat the bake boom to different ambient temperatures,and the response of explosives was observed.The critical ambient temperature was estimated according to the characteristics of the temperature rising curve.The study found that the heating rate has little effect on the critical ambient temperature of explosives,but with the decrease of heating rate,the detonation delaying time of explosives at the same ambient temperature is shorter and the damage is more serious.Study the protective effect of thermal insulation on RBOL-2 charge carrier.Contrasting the thickness of different insulation layers under fast-bake and mediumspeed bake,this paper found that the thickness of inner layer can only delay the ignition time of the explosive to a certain extent.However,when the position of the thermal insulation coating is changed to the outside of the baking bomb body,the ignition time of the bomb body in the thermal environment can be prolonged and the temperature gradient inside the explosive can be reduced.Dramatically improve the thermal safety of the projectile.