文丘里管式微气泡发生器内单气泡碎化行为的数值模拟

doi:10.16085/j.issn.1000-6613.2019-1650

摘要/Abstract

摘要：

文丘里流道内部流场及气泡破碎过程的正确表征是提升文丘里管式微气泡发生器成泡性能和对其进行结构优化设计的基础和前提。本文借助计算流体动力学（CFD）商业软件ANSYS Fluent中的VOF多相流模型，数值模拟研究单气泡在三维流场中的变形及破碎行为，揭示文丘里流道尤其是扩张段内的流场分布和气泡碎化过程，并对文丘里管式微气泡发生器成泡粒径分布不均匀的原因进行分析讨论。CFD数值模拟结果表明，气泡碎化发生在文丘里管式微气泡发生器的扩张段内，湍流耗散率越大，碎化生成微气泡的粒径越小。扩张段内中心区域的湍流耗散率远小于边壁区域，湍流耗散率径向位置分布的差异将直接导致所生成微气泡粒径分布的不均匀。在轴心线方向上，单气泡由进水管注入时的碎化程度强于由喉管处注入；在径向方向上，单气泡由进水管偏心位置注入时的碎化程度强于由中心位置处注入。进水管内安放带导流叶片的轴向静止起旋元件，不仅可提高扩张段的平均湍流耗散率，降低生成微气泡的平均粒径，而且可以降低径向湍流耗散率的标准差，增强扩张段内径向湍流耗散率的均匀度，进而提高所生成微气泡粒径分布的均匀程度。

关键词: 文丘里, 湍流, 微气泡, 气液两相流, 数值模拟

Abstract:

The proper characterization of the flow field and bubble breaking process in Venturi channel is the basis for improving the bubble producing and structure optimization of Venturi microbubble generator. In this paper, the single bubble deformation and breaking was simulated using VOF multiphase flow model in three-dimensional flow field. On the basis of simulation model verification, the flow field distribution and bubble fragmentation process in the Venturi channel, especially in the expansion section, were revealed. The reason of the uneven distributing microbubbles which produced by the Venturi microbubble generator was also discussed. The numerical simulation results showed that bubble fragmentation occurs in the expansion section of the Venturi microbubble generator. The microbubble diameter decreased when the turbulent energy dissipation rate increases. The turbulent energy dissipation rate in the central region of the expansion section is much smaller than that in the sidewall region. The uneven diameter distribution of microbubbles is directly due to the turbulent energy dissipation rate in the radial direction. In the axial direction, the fragmentation degree of single bubble injected from the inlet position is stronger than that injected from the throat position. In the radial direction, the fragmentation degree of the single bubble injected from the eccentric position is stronger than that injected from the central position. The axial static swirling element can increase the average turbulent dissipation rate in the expansion section and reduce the average microbubble diameter. Besides, it can also reduce the standard deviation of radial turbulent dissipation rate. By enhancing the uniformity of radial turbulence dissipation in the expansion section, the particle size distribution of microbubbles can be improved.

Key words: venture, turbulence, microbubbles, gas-liquid flow, numerical simulation

中图分类号:

TH113

丁国栋, 陈家庆, 蔡小垒, 叶帆, 李振林, 姬宜朋, 郭靖. 文丘里管式微气泡发生器内单气泡碎化行为的数值模拟[J]. 化工进展, 2020, 39(7): 2590-2598.

Guodong DING, Jiaqing CHEN, Xiaolei CAI, Fan YE, Zhenlin LI, Yipeng JI, Jing GUO. Numerical simulation of single bubble breaking behavior in Venturi microbubble generator[J]. Chemical Industry and Engineering Progress, 2020, 39(7): 2590-2598.

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