颗粒流体气液相分离

One of the challenges of physics in the twenty-first Century was the urgency of establishing the laws of complex systems. Microgravity environment provides the necessary conditions for the study of gas-liquid phase separation behavior of granular flows. The conditions of granular gas - liquid phase transition were studied in SJ-10 satellite experiment. The satellite provided the long low gravity observation time. Three single-cell chambers were used for cluster-forming condition experiment, and a double-cell chamber was used for segregation experiment. Free cooling was also studied. We aimed to search for some new method to store, transport and manipulate particles in low gravity environment taking advantage of particles’ intrinsic energy dissipation mechanism. In this work we will focus on the analyses of 37 sets data from single-cell and 95 sets data from double-cell successfully obtained in SJ-10. We will compare the results with that obtained from the existing ground and drop-tower experimental analyses and our numerical simulation results, including granular free cooling, gas - liquid phase separation and the phase diagram, as well as the segregation conditions in two-cell chamber. Based on the comparison results, we will perform some targeted computer numerical simulation, and ground and/or satellite, as well as some necessary parabolic flight or drop tower experiment as supplementary experiments, to obtain a comprehensive cluster phase diagram, to set up conditions for free cooling and gas-liquid phase transition, to make improvement of the current theoretical model, in hoping that the space particle transportation method can be established.

二十一世纪物理的挑战之一在于对复杂系统规律认知的迫切性。微重力环境为颗粒流体气液相分离行为研究提供了必要条件。实践十号返回式卫星具备探寻颗粒气体气液相变形成条件所需的长时间和零重力观测条件，利用颗粒单仓、双仓实验装置，观察颗粒的团簇/分聚形成条件，研究颗粒气体团簇形成条件与双仓分聚现象，利用颗粒流体内禀的能量耗散特性达到建立空间颗粒定向输运新方法的目的。本项目我们将针对实践十号成功获得的37 组单仓空间实验结果和95 组双仓空间实验结果进行分析，与已有地面和落塔实验结果以及数值模拟结果进行比对，获得包括颗粒自由冷却、颗粒气-液相分离及其相区、以及颗粒双仓分聚条件。在获取的数据的基础上，进行针对性的计算机数值模拟，和必要的地面及卫星、抛物线飞机或落塔等微重力补充实验，以获得完整团簇相图、颗粒自由冷却及类气-液相分离模型、颗粒双仓分聚条件，建立完善理论模型，并建立可能的空间颗粒输运新方法。

颗粒体系团簇形成机理与条件一直是物理学家所感兴趣的焦点之一，对此现象的认知有助于人们理解远离平衡态复杂体系的有序结构和麦克斯韦妖等现象。实践十号卫星单双仓实验为颗粒气体团簇形成的颗粒相分离理论模型提供实验观测数据，本项工作对实验结果进行数据分析，对颗粒碰撞自由冷却、单仓振动激发团簇形成影响因素、双仓分聚等进行了DEM数值模拟。颗粒能量损耗有两个影响因素，一为恢复系数，另一个是摩擦系数。我们对实验中使用的钛颗粒设计了实验测量方法，确定了颗粒恢复系数、对颗粒级配引起的分层效应进行了三维测量、并对颗粒间摩擦系数影响，建立了本构模型，由重力和微重力下阻力实验予以验证。取得的重要结果包括分析SJ-10首次观测到微重力下双仓颗粒分聚，即麦克斯韦妖现象，对颗粒体系中观察到的团簇现象建立颗粒相分离理论模型；对颗粒分聚现象建立三维观察方法；建立颗粒固态到流变本构模型。