Research On The Effect Of Size Effect On The Flaming Characteristics Of Explosives

Cook-off test is an important test to test and evaluate the thermal safety performance of ammunition.There are many researches on the flaming experiment,which involves a wide range of aspects.However,there are few studies on the effect of ammunition size on the response characteristics,and the charge size is one of the important factors affecting the flammability response of the ammunition.Therefore,it is of great significance to study the flammability response characteristics and its laws of different sizes of ammunition for the design of the insensitive warhead.In this paper,firstly,the response characteristics of roasted roasters filled with DNAN fusion casting explosive and JH-95 explosives at a heating rate of 1.0°C/min were experimentally investigated.The experimental results show that the size of the charge has an important influence on the response temperature,response time and response level of the roasted flares.On this basis,Fluent software was used to simulate the effects of the length of the pellet and the diameter of the pellet on the response temperature,ignition position,number of ignition points,and the division of fast and slow flaming.The following conclusions were obtained:(1)In the case of constant charge diameter,when the heating rate is 1.0°C/min,the response temperature of roasting pellet exponentially decreases with the increase of the length of the pellet.When the length of the grain increases to a certain value,the response temperature tends to be constant.At the same time,it was found that the influence of the response temperature on the response temperature and length is similar when the diameter of the drug column is different,but the absolute value of the response temperature has a great relationship with the diameter of the charge.(2)At a temperature increase rate of 1.0°C/min,there is a critical diameter,which changes the trend of the response temperature with the diameter of the pellet.When the diameter of the drug column is smaller than the critical diameter,the ambient temperature at the time of response decreases with the increase of the diameter.When the diameter of the drug column is larger than the critical diameter,the ambient temperature at the time of response increases with the increase of the diameter.The critical diameters of the two explosives under the conditions of this study are between 20 mm and 30 mm.At the same time,the response time temperature of the different lengths of the drug column is similar to the change of the diameter of the drug column,but the absolute value of the response temperature has a great relationship with the length of the drug column.(3)The charge size of the explosive is an important factor that influences the ignition position during the flaming response.At a temperature increase rate of 1.0 °C/min,when the diameter of the charge is small,the ignition position of the explosive does not change with increasing the aspect ratio,and the ignition position is in the center of the pellet.When the diameter of the charge is larger,the ignition position changes with the increase of the aspect ratio,that is,with the increase of the length-diameter ratio,the ignition position moves from the center of the drug column to both ends of the drug column and corners of the drug column.(4)At a determined heating rate,the size of the explosive charge affects the conversion of the cook-off mechanism.At 1.0 °C/min heating rate,when the charge diameter is small,different lengths of the drug are slow cook-off.When the charge diameter is larger,the length of the drug column increases,gradually changing from slow r cook-off to medium-rate cook-off or even rapid cook-off.