斜槽中密集颗粒流的数值研究

发布时间：2018-04-09 13:15

本文选题：散裂靶　切入点：颗粒流　出处：《中国科学院大学(中国科学院近代物理研究所)》2017年博士论文

【摘要】：密集颗粒流靶是为满足ADS系统超高束流功率需求而提出的新型高功率散裂靶概念设计。在这基础上,针对聚变材料研究专用中子源,近物所ADS散裂靶团队提出了重力驱动的斜槽颗粒流靶概念设计。利用密集颗粒流作为靶材料及换热剂,密集颗粒流靶在实现离线换热功能的同时,可以避免液态重金属的流动不稳定、材料腐蚀、及化学毒性泄露等诸多致命缺陷,为满足聚变材料研究专用中子源的靶系统提供了一种很有潜力的解决方案。作为一种新型的靶系统概念设计,密集颗粒流靶中的颗粒流动行为与常规液态重金属有所不同,而最重要的区别就是流动稳定性。本论文从分析颗粒流动稳定性目的出发,利用离散元方法模拟了颗粒在斜槽上的流动行为,通过分析颗粒速度、体积分数空间场以及它们的波动来研究流动的稳定性,进而通过线性稳定性分析以及计算扰动后能量差的李雅普诺夫指数,进一步研究颗粒在斜槽上流动的稳定性,此外也研究了模型的几何及材料参数对流动的影响,最后对靶系统设计的可行性进行了评估。本论文主要研究三个方面的工作:(1)在周期边界条件下,模拟了颗粒在倾斜面(规则六边形颗粒排布)上的流动行为,主要研究了斜面倾斜角对流动的影响;(2)模拟了颗粒在斜槽的供料水库中的流动行为,研究了模型的几何参数对流动的影响,并分析了颗粒在供料水库中以及斜面上的速度、体积分数空间场及它们的波动;(3)提出了斜槽颗粒流靶的概念设计,研究了模型的几何和材料参数对流动的影响,最后通过线性稳定性分析以及计算扰动后能量差的李雅普诺夫指数,来研究颗粒在斜槽上流动的稳定性。具体内容如下:首先我们研究了周期边界条件下颗粒在斜面上的流动行为:首先介绍了在离散元方法中周期边界条件的实现原理;然后对模型进行了描述以及对模拟过程进行了简单介绍;最后主要分析了斜面倾斜角度对流动的影响。然后研究了颗粒在斜槽的供料水库中的流动行为:首先分别研究了供料水库以及斜面的倾斜角对流动的影响;然后由于供料水库类似于偏心漏斗,研究了颗粒在偏心漏斗中的流动行为,包括漏斗宽度、开口宽度对流量的影响以及偏心漏斗中的体积分数、速度场及其波动;最后研究了供料水库的开口高度对流动影响,包括对流量的影响以及颗粒在整个装置体积分数、速度场及其波动。接着研究了斜槽颗粒流靶中颗粒在斜槽上的流动行为:首先我们提出了斜槽颗粒流靶的概念设计,将模拟进行了一定简化;然后研究了模型的几何和材料参数对流动的影响;最后通过线性稳定性分析以及计算扰动后能量差的李雅普诺夫指数,来研究颗粒在斜槽上流动的稳定性。最后总结了全文,并展望了下一步的研究工作。
[Abstract]:Dense particle flow target is a new type of high power spallation target conceptual design proposed to meet the demand of ultra-high beam power in ADS system.On this basis, for the study of special neutron source for fusion materials, the ADS spallation target team of the near object proposed the gravity driven oblique particle flow target conceptual design.Using the dense particle flow as the target material and heat exchanger, the dense particle flow target can realize off-line heat transfer function while avoiding many fatal defects such as liquid heavy metal flow instability, material corrosion, chemical toxicity leakage and so on.It provides a promising solution for the target system of specific neutron source for fusion material research.As a new conceptual design of target system, the flow behavior of particles in dense particle flow targets is different from that of conventional liquid heavy metals, and the most important difference is the flow stability.For the purpose of analyzing the flow stability of particles, the flow behavior of particles on a chute is simulated by using discrete element method. The flow stability is studied by analyzing particle velocity, volume fraction space field and their fluctuations.Furthermore, the stability of particle flow on the slant channel is further studied by linear stability analysis and Lyapunov exponent of the energy difference after disturbance. The effects of geometry and material parameters of the model on the flow are also studied.Finally, the feasibility of target system design is evaluated.This paper mainly studies three aspects of work: 1) under the periodic boundary condition, the flow behavior of particles on inclined plane (hexagonal particle arrangement) is simulated.The effect of inclined angle on flow is studied. The flow behavior of particles in a sloping reservoir is simulated, the effect of geometric parameters of the model on flow is studied, and the velocity of particles in feed reservoir and inclined plane is analyzed.The volume fraction space field and their fluctuation are presented in this paper, and the effects of geometry and material parameters of the model on the flow are studied.Finally, the stability of particle flow in a chute is studied by linear stability analysis and Lyapunov exponent of energy difference after disturbance.The main contents are as follows: firstly, we study the flow behavior of particles on the oblique plane under periodic boundary conditions; first, we introduce the realization principle of periodic boundary conditions in discrete element method;Then the model is described and the simulation process is briefly introduced. Finally, the influence of inclined angle on the flow is analyzed.Then the flow behavior of particles in the inclined channel feed reservoir is studied. Firstly, the influence of the inclined angle of the feed reservoir and the inclined plane on the flow is studied, and then, because the feed reservoir is similar to the eccentric funnel,The flow behavior of particles in eccentric funnel is studied, including the influence of funnel width, opening width on flow rate, volume fraction, velocity field and fluctuation in eccentric funnel.It includes the influence on the flow rate and the volume fraction, velocity field and fluctuation of the particle in the whole device.Then, the flow behavior of the particles in the slit particle flow target is studied. Firstly, the conceptual design of the slanted particle flow target is proposed, and the simulation is simplified, then the effects of the geometry and material parameters of the model on the flow are studied.Finally, the stability of particle flow in a chute is studied by linear stability analysis and Lyapunov exponent of energy difference after disturbance.Finally, the paper summarizes the full text and looks forward to the next research work.
【学位授予单位】：中国科学院大学(中国科学院近代物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O571.5

【相似文献】