爆轰驱动下金属颗粒与气体混合运动的建模与模拟研究

发布时间：2018-05-19 04:31

本文选题：爆轰驱动 + 喷射混合　；参考：《中国工程物理研究院》2016年博士论文

【摘要】：金属材料经历强冲击后将发生碎裂,产生的颗粒物质与背景气体发生混合流动现象,简称喷射混合。开展喷射混合研究,对于深入理解高温高压条件下的气粒两相流动、认识混合对压缩过程的影响,以及优化和改进内爆工程设计等具有重要意义。喷射混合的理论建模与数值模拟,是当前内爆压缩科学领域亟需解决的难点和热点问题,涉及多相流体力学、传热传质学、计算数学等多学科交叉研究。本文在系统调研分析国内外喷射混合研究的基础上,针对爆轰驱动下不同阶段喷射混合过程,开展喷射金属颗粒与气体混合运动的理论建模和数值模拟研究,分析和讨论气粒混合时空发展形态及其对内爆压缩过程的影响规律。在爆轰驱动早中期的喷射混合研究方面,基于典型爆轰流场条件,开展了气粒相间作用分析,确定了相间力、热耦合相互作用的主导项,获得了相应的驰豫特征。推导了拉格朗日坐标系下,含双向耦合效应的颗粒轨道模型控制方程组,明确了相间作用源项的物理含义；提出了适用于极端网格的颗粒搜索策略,以及气相空间向颗粒相空间的二阶映射算法,有效解决了颗粒失联和混合流场中的非物理空穴问题,给出了与守恒律计算一致的交错型格式,实现了耦合源项稳定的算法；设计了平面及圆柱的计算模型,进行了喷射混合数值模拟,发现颗粒反馈改变了纯气体中激波传播的时序过程,并且引起气区流场物理量分布形态变化。特别对于汇聚构型装置,几何收缩效应将进一步放大颗粒的反馈作用。在爆轰驱动中晚期的喷射混合研究方面,凝练了中晚期喷射混合需要关注的科学问题,即聚心反射激波在喷射混合流场中的传播行为以及喷射混合流场的汇聚压缩特性。针对此阶段问题的特点和稠密气粒两相流动特征,开展了双流体模型的适用性研究；基于喷射混合物理现象的分析,提出了气体-颗粒混合规则,推导了混合流场关键物理量的计算表达式,给出了适用于稀相到密相统一的等熵声速计算公式。在此基础上,针对不同颗粒负载,研究了等熵声速的变化规律和机理,分析了颗粒相压力建模参数的物理含义；对喷射混合流场中的激波传播进行了数值模拟,获得了不同颗粒质量分数条件下激波传播的动力学行为。研究了典型颗粒分布形态和不同喷射量情况下,喷射混合流场的汇聚压缩特性和规律,发现了喷射量是影响汇聚压缩晚期流场状态的关键物理因素。
[Abstract]:Metal materials will break apart after strong impact, resulting in mixed flow of particulate matter and background gas, or jet mixing. The study of jet mixing is of great significance to understand the gas-particle two-phase flow at high temperature and pressure, to understand the influence of mixing on the compression process, and to optimize and improve the design of implosion engineering. The theoretical modeling and numerical simulation of jet mixing is a difficult and hot problem in the field of implosion compression science. It involves multi-phase fluid dynamics, heat and mass transfer, computational mathematics and other interdisciplinary cross-research. On the basis of systematic investigation and analysis of jet mixing at home and abroad, the theoretical modeling and numerical simulation of the mixing motion of metal particles and gases under different stages of detonation drive are carried out in this paper. The spatiotemporal development of gas-particle mixing and its influence on the implosion compression process are analyzed and discussed. In the study of jet mixing in the early and middle period of detonation drive, based on the typical detonation flow field conditions, the gas-particle interaction analysis is carried out, and the dominant terms of the interaction between phase force and heat are determined, and the corresponding relaxation characteristics are obtained. In Lagrangian coordinate system, the governing equations of particle orbit model with bidirectional coupling effect are derived, the physical meaning of the source term of interphase interaction is clarified, and the particle search strategy suitable for extreme grid is proposed. The second order mapping algorithm from gas phase space to particle phase space effectively solves the non-physical hole problem in the particle disconnection and mixed flow field, and gives a staggered scheme consistent with the calculation of conservation law, and realizes the stability algorithm of coupling source term. The computational models of plane and cylinder were designed and the numerical simulation of jet mixing was carried out. It was found that particle feedback changed the time series of shock wave propagation in pure gas and caused the change of physical quantity distribution of flow field in gas region. Especially for convergent devices, the effect of geometric shrinkage will further amplify the feedback effect of particles. In the research of jet mixing in the middle and late stage of detonation drive, the scientific problems that need to be paid attention to in the middle and late stage jet mixing are condensed, that is, the propagating behavior of the concentrated core reflected shock wave in the jet mixing flow field and the convergent compression characteristics of the jet mixed flow field. According to the characteristics of this stage problem and the characteristics of dense gas-particle two-phase flow, the applicability of two-fluid model is studied, and the gas-particle mixing rule is proposed based on the analysis of jet mixing physical phenomena. The expression of the key physical quantities in the mixed flow field is derived, and a formula of isentropic sound velocity is given, which is suitable for the unity of rarefied and dense phases. On this basis, the variation law and mechanism of Isentropic sound velocity are studied for different particle loads, the physical meaning of modeling parameters of particle phase pressure is analyzed, and the shock wave propagation in jet mixing flow field is numerically simulated. The kinetic behavior of shock wave propagation under different particle mass fraction is obtained. The convergent compression characteristics and rules of jet mixing flow field under typical particle distribution and different injection amount are studied. It is found that jet quantity is the key physical factor affecting the state of late convergent compression flow field.
【学位授予单位】：中国工程物理研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O359

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