基于三维离散元方法探究奥克托今颗粒落锤撞击点火机理

Three-dimensional discrete element technology investigated ignition mechanism of octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine particles under drop hammer impact

炸药颗粒的冲击点火机理一直是人们关注并不断研究的课题,但是迄今为止进展缓慢.随着计算技术的高速发展,三维离散元方法(three-dimensional discrete meso-element method,DM3)被认为是一种高效且直观的研究炸药冲击点火的有效手段.本文基于三维离散元方法对奥克托今(HMX)颗粒在落锤撞击条件下的撞击变形和升温点火进行了研究,模拟计算表明,炸药的颗粒尺寸、堆积程度、内部缺陷以及落锤的冲击力大小都将影响HMX颗粒的升温点火和燃烧蔓延.同时,基于以上结果,本文提出了尖顶变形加热点火机制以及平顶颗粒剪切加热机制.特别地,含内部缺陷的HMX颗粒在冲击条件下将出现两种情况:尺寸较大的颗粒在孔洞处出现温度优势,颗粒尺寸较小的温度优势出现在尖顶位置.

The ignition mechanism of the explosive particles under impact has been a hot topic,but the research progress is slow.With the rapid development of computer science,the three-dimensional discrete element technique(DM3)is regarded as an efficient and intuitive method to study the explosive ignition under impact.As is well known,octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX)is one of the most effective explosive particles in performance,which has high density and energy and thus possesses a significant application.In this paper,the deformation and ignition of HMX particles under impact of drop hammer are investigated based on the three-dimensional discrete element technique.Specifically,the computational process for shock loading as well as chemical reaction is employed in DM3 model through using the state equation of Hugoniot,the reactive model of Arrhenius,the state equation of JWL.The results show that the size,degree of accumulation,defect and the force of drop hammer can definitely influence the ignition and propagation of HMX particles.Under the same shock loading,the particles on a small scale would produce less power.On the same scale of particle,the less the number of particles,the shorter the deformation time is,so the temperature increases more easily.As for the different shapes of single particles,the deformation and ignition first appear from the‘top’for the spire particles,and then the deformation and ignition of flat particles happens from‘shear’.Specifically,there are two results of the internal defect HMX particles under impact:the particles with bigger size(discrete elements 256×34=8704)have a temperature advantage near the‘hole’,while the temperature advantage of the particles with the smaller size(discrete elements 93×35=3814)appears on the‘top’.