冷压过程对球堆积结构渗透率的影响

空间轴承的供油系统主要目标是实现对飞轮轴承的长时间、稳定、微量供油，利用微孔介质的复杂结构可能有效实现这一目标，但目前的渗流机理和规律尚不明晰，主要问题在于多孔介质结构难以调控、多孔结构与渗透率之间的关系复杂、渗透率受装配压力影响等.芯阀材料一般经过两步制成：先对颗粒物质进行冷压，再对冷压得到的结构进行烧结得到成品.目前的生产过程主要以经验为主，机理不清，难以精准调控.本文在数值上结合离散单元法与格子玻尔兹曼方法对颗粒堆积结构在冷压过程中的渗透率变化进行了研究.采用离散单元法模拟颗粒堆积结构冷压过程，再用格子玻尔兹曼方法进行渗流模拟，得到不同摩擦角下得到的冷压结构的渗透率变化.本研究为全面揭示多孔介质冷压结构与渗透率的关系及其微观机理奠定了基础.

Effect of Cold Compaction on Permeability of Sphere Stacking Structure

The main goal of the bearing lubrication replenishment system is to achieve long term, stable, and minimal lubricant supply to the flywheel bearing. The complex structure of the microporous medium may be effective to achieve this goal, but the current seepage mechanism and law are not yet clear. The main problems are that the porous media structure is difficult to control, the relationship between the porous structure and permeability is complex, and the permeability is affected by assembly pressure. The valve is generally made in two steps: first cold pressing the particulate matter, and then sintering the structure obtained by cold pressing to obtain the finished product. The current production process is mainly based on experience. The mechanism is unclear, and it is difficult to accurately control. In this paper, the Discrete Element Method and Lattice Boltzmann Method are combined numerically to study the permeability change of the particle packing structure during the cold pressing process. The Discrete Element Method is used to simulate the cold pressing process of the particle accumulation structure, and then the Lattice Boltzmann Method is used to simulate the seepage flow. The permeability change of the cold pressed structure under different friction angles is obtained. This study lays the foundation for a comprehensive disclosure of the relationship between the cold pressed structure of porous media and permeability and its microscopic mechanism.