均匀强磁场下金属液膜流动不稳定性机理研究

With the action of electromagnetic force under the magnetic field, the metal film flows will become very unstable and unable to well spread on the surface of solid. Moreover, with the increasing of magnetic field, the flow characteristics of metal flow will show more complex. This program is mainly focused on investigating the flow instability of Gallium Indium Tin alloy (GaInSn, which is liquid state at room temperature) film flow in the uniform strong magnetic field using experimental method and numerical simulation method. Firstly, the homemade liquid film measurement system is used to get metal film flow characteristics (such as the instantaneous metal film thickness, instantaneous metal film shape of surface wave and so on) in magnetic field. The influence of flow inlet condition and magnetic field intensity on flow characteristics of metal film are also studied in detail. Secondly, by using two phase model and combined with the high-precision consistent and conservative scheme to calculate electromagnetic force, the liquid film flow simulations are carried out to get some important parameters which can not be measured quality in experiments such as velocity distribution, electric potential distribution in metal film and so on. Furthermore, the instability mechanisms of metal film flow in magnetic field are also studied by compare with experimental data and numerical simulation data. Finally, the method which can control the flow instability of metal film in magnetic field and realize the large area, uniform spread on solid surface of metal film can be put forward. The research results of this program can provide some references on the application of metal film in the thermonuclear fusion Tokamak equipment to protect the plasma facing component.

在磁场环境下，金属液膜流动受到电磁力作用所产生的不稳定流动现象使得其无法很好地铺展于固体壁面，且随着磁场强度的增强，液膜流动不稳定变得更为复杂。本项目旨在对室温下液态镓铟锡合金在均匀强磁场下所形成的液膜流动不稳定特性从实验和数值模拟方面进行研究。首先采用自行设计的金属液膜形态测量系统对磁场中流动金属液膜的瞬时厚度、瞬时表面波形态等进行详细的测量，以获得不同流动入口和磁场影响下液膜流动的特征；随后通过采用两相方法，结合电磁力计算所需的高精度相容守恒格式对金属液膜流动进行数值模拟，以获取实验中无法得到的液膜内部速度分布、电势分布等信息，并通过与实验结果对比分析，探索磁场下金属液膜产生不稳定现象的机理；最终通过寻求控制不稳定现象产生的方法，从而实现磁场下金属液膜在固壁材料上大面积、均匀铺展，为金属液膜流动在核聚变托克马克装置中作为等离子体面对部件的应用提供参考。

液态金属膜流是磁约束核聚变堆中面对等离子壁面实现一种重要方式之一。然而受到聚变堆中磁场环境的影响，金属液膜流动将受到电磁力作用而产生各种流动不稳定现象并导致其无法实现保护面对等离子体固体壁面的功能，亟需对金属液膜在磁场中产生的这些现象开展大量的基础研究。本项目以此为背景系统地开展了液态镓铟锡膜流在磁场中的流动特性实验及相关的研究。主要包括：基于常规可视化方法和激光测量技术发展了对于不透明液态金属表面波及膜厚的测量方法，并采用该方法对金属液膜流动在不同润湿特性底板、不同磁场强度、不同初始流速影响下的流动特性进行了系统的测量；随后通过采用两相方法，结合电磁力计算所需的高精度相容守恒格式对金属液膜流动开展了数值模拟研究；最后对膜流不稳定流动过程中所产的飞溅液滴在磁场环境下撞击固壁铺展现象开展了初步的研究。通过以上研究获得如下结论：1. 激光测量技术能较好地获得不透明液态金属表面波动形态以及对应液膜厚度的瞬态信息；2. 金属液膜厚度随着流量的增大而逐渐增加，随着磁场强度增大呈现先减小后增大的趋势；3. 展向磁场的作用会使得液膜表面波动变得更为规则化，即使得展向的波动逐渐消失，流向波动变得更为规则且表面波速明显减小，这一现象得到了数值模拟的进一步验证；4. 在液滴铺展方面，水平磁场的作用使得液滴的铺展产生了各向异性的现象，即平行于磁场方向的铺展宽度小于垂直于磁场方向的铺展宽度，且这一现象随着磁场变得更为明显。该项目的研究成果发表学术论文5篇，其中在核聚变专业期刊Fusion Engineering and Design 和流体力学顶级期刊Physics of Fluids各一篇，同时在实现液态金属在固壁均匀铺展方面获得发明专利2项。项目的相关研究成果为磁约束核聚变中液态第一壁的实现提供了丰富的基础实验数据和技术参考，具有重要的意义。