The Influence Of Free-space On Response Characteristics Of The Explosive On Slow Cook-off Condition

This thesis aimed at studying the influence of free-space on response characteristics ofexplosive on slow cook-off condition. The research results could be regard as an support toolto the safe use of ammunition.First of all, according to the theory of thermal explosion, the numerical solution of criticaltemperature of the thermal explosion and Frank-kamenetskii parameter crunder the differentaspect ratio of the high explosive of RDX-based was established, which is the way of theRDX-based explosives in different aspect ratio. The results show that: as the increase ofaspect ratio, critical temperature and Frank-kamenetskii parameter crdecrease. When thevalue of aspect ratio is higher than5, the critical temperature and Frank-kamenetskiiparameter crcomes to a certain value. So it can come to an conclusion that increasing thediameter enhance the possibility of warhead’s thermal vulnerability.Then studied the influence of free-space on cook-off response in high explosive ofRDX-based. The results show that: the thermal response characteristics changed with differentfree spaces. As free-space ratio in10.25%～29.09%, the violence of the reaction increaseswith the increase of free-space. When free-space ratio greater than29.09%, the violence of thereaction decreases with the increase of free-space. The responses are explosion reactionswhen free-space ratio is45.71%. Observed by the recycling of the fragment, the responseintensity is same with no free-space. So it can be seen, response intensity of the thermalexplosion increased when it have free-space.Apart from the theoretical calculations and the experimental study, FLUENT software wasapplied to simulate the process that the radial direction, axial direction and both way directionfree-space affects the thermal response characteristics. Results of the simulation show that:when the free-space in a certain range, radial direction, axial direction and both way direction free-space have almost same regular in influencing the thermal ignition delay time and theshell wall temperature of thermal explosion of cook-off bomb. The thermal ignition delaytime and the shell wall temperature of thermal explosion of cook-off bomb increased whenfree-space increase. Radial direction and both way direction free-space beyond this range, thethermal ignition delay time and the shell wall temperature of thermal explosion of cook-offbomb decreases. In addition, radial direction and both way direction free-space also havesome influence on the ignition place and ignition quantity of cook-off bomb, however, axialdirection free-space have no influence on the ignition place and ignition quantity of cook-offbomb, this simulation result again theoretically explains the effect free space has effect oncook-off test.The safely use of warheads in practical work and the design of lower vulnerabilitywarheads can benefit a lot from these results, which can be seen as an support tool.