Dynamics of Energetic Events in Condensed Phase Media

凝聚相介质中能量事件的动力学

• 批准号: RGPIN-2014-06258
• 负责人: Higgins, Andrew
• 金额: $ 2.84万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=653550
• 关键词: Dynamics; Energetic; Events; Condensed; Phase

Highly energetic events occur when the rate of energy release exceeds the strength of the material into which the energy is deposited. Under these conditions, the ensuing dynamics of the media is governed by compressible (nonlinear) waves such as shock waves. While these phenomena are far outside everyday experience, they play an important role in a number of natural processes and technological applications. This proposed experimental and theoretical research program will focus on three topics involving the problems and applications of the dynamics of energetic events, with an emphasis on the nonlinear wave aspects of the problems.**Discrete Detonation: The propagation of detonation waves through energetic material, releasing stored energy as it propagates, is an example of a highly energetic event with important technological applications, since explosives are extensively used in mining and earth moving. Recent experimental results by the author, his colleagues, and researchers elsewhere have identified behavior of detonation waves in heterogeneous, condensed phase materials that cannot be explained by purely classical, continuum-based models of detonation wave propagation. These results suggest that phenomena occurring at the mesoscale (e.g., grains, voids, etc.) may have significant influence on the propagation of the wave. This research program will further investigate this effect experimentally as well as develop a methodology for modeling detonation propagation in media dominated by discrete, energetic events.**Implosion Dynamics: The response of materials exposed to highly dynamic events is also of considerable interest. My students and I have recently undertaken a study of the dynamics of cylinders that are impulsively imploded. This work was originally motivated by the development of the hypervelocity launcher described below, but has direct relevance to approaches to harness thermonuclear fusion for power generation (i.e., inertial confinement and magnetized target fusion). We will be continuing these studies under the proposed program, focusing upon the stability of dynamically loaded converging geometries (imploding cylindrical cavities) in both solids and liquids in order to determine the limits to symmetric compression that can be achieved and the role of material properties and hydrodynamic instabilities.**Hypervelocity Launcher and Impact: Another example of an energetic event is the hypervelocity impact of orbital debris or micrometeoroids on spacecraft. This mounting problem is now widely recognized due to the runaway cascade of collisions generating new debris in Earth orbit. These types of impacts occur at speeds of 7 to 70 km/s (for naturally occurring micrometeoroids), a regime that is not presently accessible in the laboratory. At impacts exceeding 10 km/s, the impact-generated pressures are sufficient to overcome the repulsion barrier between outer electron shells, giving rise to novel structural phase transitions, and upon pressure release, many engineering materials enter a region of mixed liquid and vapor states. These phenomena have not been previously studied due to their experimental inaccessibility in the laboratory. A unique hypervelocity launcher that uses explosives to dynamically implode the launcher propellant gas has recently been developed by my group at McGill, and has now demonstrated the ability to exceed the projectile velocity of conventional launchers. This research program will continue the development of the hypervelocity launcher and apply it to both fundamental problems in impact physics as well as examination of materials of interest for spacecraft shielding.

高能事件发生在能量释放速率超过储存能量的物质的强度时。在这些条件下，介质的后续动力学由可压缩(非线性)波(如冲击波)控制。虽然这些现象远远超出日常经验，但它们在许多自然过程和技术应用中发挥着重要作用。这项拟议的实验和理论研究计划将集中在涉及高能事件动力学问题和应用的三个主题上，重点放在问题的非线性波动方面。**离散爆轰：爆轰波通过含能材料传播，在传播时释放储存的能量，是具有重要技术应用的高能事件的一个例子，因为炸药广泛用于采矿和土方搬运。作者、他的同事和其他地方的研究人员最近的实验结果确定了爆轰波在非均质凝聚相材料中的行为，这种行为不能用纯经典的、基于连续介质的爆轰波传播模型来解释。这些结果表明，在中尺度上发生的现象(例如，颗粒、空洞等)可能会对波的传播产生重大影响。这项研究计划将通过实验进一步研究这种影响，并开发一种方法来模拟爆炸在离散、高能事件主导的介质中的传播。**内爆动力学：暴露在高动态事件下的材料的反应也引起了相当大的兴趣。我的学生和我最近进行了一项关于气缸内爆动力学的研究，这些气缸都是冲动内爆的。这项工作最初的动机是开发下文所述的超高速发射器，但与利用热核聚变发电(即惯性约束和磁化靶聚变)的方法有直接关系。我们将在拟议的计划下继续这些研究，重点放在固体和液体中动态加载的会聚几何形状(内爆圆柱腔)的稳定性，以确定可以实现的对称压缩极限以及材料特性和流体动力学不稳定性的作用。**超高速发射器和撞击：另一个高能事件的例子是轨道碎片或微流星体对航天器的超高速撞击。由于在地球轨道上产生新碎片的一连串碰撞失控，这个不断增加的问题现在得到了广泛的认识。这些类型的撞击以7至70公里/S的速度发生(对于自然形成的微流星体)，这一机制目前在实验室中无法实现。当撞击速度超过10公里/S时，冲击产生的压力足以克服外层电子壳层之间的排斥势垒，产生新的结构相变，当压力释放时，许多工程材料进入液态和汽态混合区。这些现象以前没有被研究过，因为它们在实验室里是实验不到的。我在麦吉尔的团队最近开发了一种独特的超高速发射器，它使用炸药动态内爆发射器推进剂气体，现在已经展示了超过传统发射器的弹丸速度的能力。这项研究计划将继续发展超高速发射器，并将其应用于撞击物理的基本问题以及航天器屏蔽感兴趣的材料的检查。