Numerical Simulation Of The Burning Of Defective Condensed Phase Explosives

Energetic materials encountered unexpected thermal stimuli during storage,transportation,and use,such as sudden fires at the storage location or during transportation,sudden fire accidents on the battlefield,frictional heat during launch or flight,and nuclear explosion Strong radiant heating.These thermal stimuli may cause ignition,combustion and even explosion of energetic materials before normal use.Studying the reaction conditions and laws of energetic materials under the action of heat is of great significance for the safe production,transportation,and use of energetic materials,and their safety and adaptability.Two methods are used to study the burning phenomenon of explosives.The burning test can directly and effectively evaluate the thermal safety characteristics of explosives.The standard burning test is a phenomenological qualitative test with high cost,high risk,long research period,and limited measurement data.Numerical analysis methods can easily change calculation parameters,such as heating rate,charge size and constraints,etc,to comprehensively analyze the thermal reaction process of explosives.The use of numerical simulation methods can help reduce the number of experiments,shorten the research cycle and reduce the research cost,and clarify the combustion mechanism.It is particularly suitable for evaluating the thermal safety of explosives under the conditions of production,storage,use and transportation.This paper numerically simulates the burning phenomenon of PETN with charging defects after heat flow,and analyzes the burning mechanism of explosives,providing qualitative and quantitative theoretical basis for the reaction mechanism of explosives after being subjected to thermal stimulation.Hope to provide vigilance for packaging and transportation of various energetic materials.In order to prevent the accident from happening in advance,causing greater irreparable losses,the main contents and conclusions are as follows:(1)Derive the two-dimensional Fourier heat conduction equation of condensed-phase explosives with charge defects using the energy conservation method and the control volume integration method,and discretize the heat conduction equation using the classical explicit difference scheme.Formula of heat transfer model for charging defects.(2)The relationship between the specific heat capacity and temperature of PETN is measured and analyzed with an HP DSC 2+instrument.The stability analysis of the heat transfer model formula is performed to determine the calculation step size ?h and the calculation time step size ?t that can obtain convenient and reliable data.(3)Calculate and analyze the combustion mechanism of PETN charge when there are millimeter-level air defects in the explosives when there are no defects.It was found that the internal temperature distribution of the charge changed greatly,there was a large heat accumulation in the air bubble defect area,and the temperature was higher than the surrounding.The existence of defects can shorten the time of burning after PETN is heated.(4)Calculate and analyze the effect of heat flux on the burning of PETN charge in the presence of millimeter charge defects.It is found that when the heat flux density is lower than 200,the high temperature region and the ignition position will always be maintained at the defect.With the increase of the heat flow density,the high-temperature area gradually shifts from the air bubble defect to the heating boundary.When the heat flow density is greater than 613,the high-temperature area will always remain at the heating boundary.At the same time,the ignition position will always be maintained at the center of the heated boundary.With the increase of heat flow density,the ignition time is gradually shortened,but the reduction is smaller and smaller,and tends to a stable value.(5)Calculate and analyze the effect of defect position change on the combustion mechanism of PETN charge under the heat flow at 200 o'clock.It was found that the highest temperature portion of the PETN charge was distributed around the defect,and when the position of the defect was changed,the high temperature region also moved.At the same time,the change of the lateral position of the defect has less influence on the ignition time than the change of the longitudinal position of the defect.Figure[37]table[6]reference[61]...