Study On Slow Cook-off Response Characteristics Of HMX-based Thermobaric Explosive

Ammunition is prone to safety accidents when exposed to external thermal stimuli.Therefore,effective evaluation of its thermal safety has always been the focus of research in the field of energetic materials.The cook-off test is currently the most widely used evaluation method.In order to provide technical reference for thermal safety design of thermobaric explosives,this paper analyzed the slow cook-off response characteristics of thermobaric explosives by comprehensive test and numerical calculation.The main research work and its results were as follows.(1)The DSC test was used to perform thermal analysis on the two kinds thermobaric explosives.The activation energy and the pre-exponential factor of the two explosives were calculated by Kissinger method,which provided theoretical basis for slow cook-off simulation.(2)A slow cook-off test system was designed,which was consisted of the software developed by Lab VIEW program and typical hardwares,including controller,data acquisition card,thermocouple,digital I/O card etc.The results showed that the slow cook-off system could satisfy the experimental requirements,providing an effective mean for studying the thermal insensitivity of the component explosives.(3)The established slow cook-off system was used to study the response characteristics of thermobaric explosives under different charge clearance ratios at a heating rate of 1?/min.The research showed that for a certain explosive,with the increase of the charge clearance ratios,the response intensity of its increased dramatically.In order to ensure the consistency of the slow cook-off test,it is necessary to keep the same clearance of charge;The clearance rate of12.11% was found to be the critical value of combustion to detonation.(4)Multi-point temperature measurement test methods were carried out to investigate the response characteristics of HMX/F and HMX/TPU system thermobaric explosives respectively at two heating rates of 0.055 ?/min and 1 ?/min.The results showed that as the heating rate increased,the response time became shorter and the response intensity decreased,and During ignition,the high-temperature areas inside the explosives were different,so the locations where they form hot spots were different.What's more,When the heating rate was the same,the response characteristics of thermobaric explosive were different in different bonding systems.At 0.055?/min,the response level of thermobaric explosive with fluororubber as binder was higher;At 1?/min,the response levels of the two bonding systems were the same.It can be concluded that the thermal safety of HMX/TPU system thermobaric explosive was better than that of HMX/F system thermobaric explosive.(5)The model was established by FLUENT software.By comparing the test data with the simulation calculation data,the model parameters were corrected.The simulation study of slow cook-off test with different charge clearance ratios showed that the ignition position of the explosives was affected by the charge clearance;The simulation results of multi-point temperature measurement showed that with the increase of heating rate,the ignition positions of HMX/F system and HMX/TPU system thermobaric explosives moved from the center of explosive to the contact surface of explosive and its shell;At the same heating rate,two kinds of binders studied had no obvious influence on ignition position,but it might cause different ignition area.