Niu Zhiqiang, Wang Renfang, Jiao Kui, Du Qing, Yin Yan
State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China.
State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China; Sunrise Power Co., Ltd., Dalian 116085, China.
Sci Bull (Beijing). 2017 Jan 15;62(1):31-39. doi: 10.1016/j.scib.2016.11.010. Epub 2016 Nov 27.
With performance improvement of low-temperature fuel cell (FC), high reactant supply and water generation rates may induce air-water turbulence in the FC flow channel. In this research, an air-water turbulent direct numerical simulation (DNS) model is developed to simulate different droplet sizes, locations and interactions in the air-water transport processes comprehensively. It is found that a larger droplet breaks up more easily in turbulence, and a smaller droplet tends to keep lumped. The droplet at corner does not break up because it is away from channel center. The droplet interaction simulations show that the small droplets merge to form slugs, but still keep lumped in turbulence. It is suggested that two conditions need to be satisfied for droplet break up in FC flow channel, one is turbulent flow, and another is that the droplet needs to be large enough and occupy the center region of flow channel to suffer sufficient turbulence fluctuations. The DNS results illustrate some unique phenomena in turbulent flow, and show that the turbulence has significant effect on the air-water flow behavior in FC flow channel.
随着低温燃料电池（FC）性能的提升，高反应物供应速率和产水速率可能会在燃料电池流道中引发气水湍流。在本研究中，开发了一种气水湍流直接数值模拟（DNS）模型，以全面模拟气水传输过程中不同的液滴尺寸、位置和相互作用。研究发现，较大的液滴在湍流中更容易破碎，而较小的液滴则倾向于保持聚集状态。位于角落的液滴不会破碎，因为它远离流道中心。液滴相互作用模拟表明，小液滴合并形成液塞，但在湍流中仍保持聚集状态。研究表明，燃料电池流道中的液滴破碎需要满足两个条件，一是湍流，另一个是液滴需要足够大并占据流道中心区域以承受足够的湍流波动。DNS结果揭示了湍流中的一些独特现象，并表明湍流对燃料电池流道中的气水流动行为有显著影响。
