Coupling and stability of interfacial waves in liquid metal batteries
Coupling and stability of interfacial waves in liquid metal batteries
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液态金属电池界面波的耦合与稳定性
DOI：
10.1017/jfm.2018.223
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发表时间：
2017
影响因子：
3.7
通讯作者：
T. Weier
中科院分区：
文献类型：
--
作者：
G. Horstmann;N. Weber;T. Weier
研究了液态金属电池中界面波的耦合动力学及其对电池安全运行的影响。与铝电解槽类似，液态金属电池可能对磁流体动力学激发的界面不稳定性高度敏感。由此产生的波能够引发短路。由于存在可能进入共振的两个金属-电解质界面，液态金属电池中的波动动力学特别复杂。本文的第一部分是重力-毛细界面波耦合的势流分析。虽然我们在这里关注的是具有圆形横截面的液态金属电池，但该理论适用于任意稳定分层的三层系统。导出了振幅比和波频率的解析表达式。结果表明，波耦合可以完全由两个独立的无量纲参数来描述。我们进一步提供了一个去耦标准，表明波耦合将存在于大多数未来的液态金属电池。第二部分通过与多相流直接数值模拟的比较，验证了理论的正确性。伴随参数的研究进行分析的界面耦合到不同程度的系统稳定性。三种不同的耦合制度，确定涉及特征耦合动力学。对于强耦合接口，我们观察到新的不稳定性，可能有有益的影响的操作安全。
We investigate the coupling dynamics of interfacial waves in liquid metal batteries and its effects on the battery’s operation safety. Similar to aluminium reduction cells, liquid metal batteries can be highly susceptible to magnetohydrodynamically exited interfacial instabilities. The resulting waves are capable of provoking short-circuits. Owing to the presence of two metal-electrolyte interfaces that may step into resonance, the wave dynamics in liquid metal batteries is particularly complex. In the first part of this paper, we present a potential flow analysis of coupled gravity–capillary interfacial waves. While we are focusing here on liquid metal batteries with circular cross-section, the theory is applicable to arbitrary stably stratified three-layer systems. Analytical expressions for the amplitude ratio and the wave frequencies are derived. It is shown that the wave coupling can be completely described by two independent dimensionless parameters. We further provide a decoupling criterion that suggests that wave coupling will be present in most future liquid metal batteries. In the second part, the theory is validated by comparing it with multiphase direct numerical simulations. An accompanying parameter study is conducted to analyse the system stability for interfaces coupled to varying degrees. Three different coupling regimes are identified involving characteristic coupling dynamics. For strongly coupled interfaces we observe novel instabilities that may have beneficial effects on the operational safety.