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过程工程学报 ›› 2021, Vol. 21 ›› Issue (6): 658-670.DOI: 10.12034/j.issn.1009-606X.220213

• 流动与传递 • 上一篇    下一篇

单个圆形非均匀多孔颗粒绕流的数值模拟

王春雨1,2， 李承功1*， 叶 茂1   

  1. 1. 中国科学院大连化学物理研究所，辽宁 大连 116023 2. 中国科学院大学，北京 100049
  • 收稿日期:2020-07-06 修回日期:2020-07-17 出版日期:2021-06-28 发布日期:2021-06-28
  • 通讯作者: 李承功 chenggongli@dicp.ac.cn
  • 基金资助:
    甲醇制烯烃过程介尺度机制与调控及其在新一代技术中的示范应用

Numerical simulation on fluid flow past a circular heterogeneous porous particle

Chunyu WANG1,2, Chenggong LI1*, Mao YE1   

  1. 1. Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China 2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2020-07-06 Revised:2020-07-17 Online:2021-06-28 Published:2021-06-28

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摘要： 多孔颗粒两相流在工业过程中普遍存在，但多孔颗粒的内部结构几乎都是不均匀的，这可能影响颗粒与流体间的相互作用。采用基于本征相平均速度的体积平均宏观控制方程描述多孔颗粒内部和外部的流体流动，采用改进的格子Boltzmann方法(LBM)求解广义的宏观控制方程，并对二维流体流过非均匀多孔颗粒进行了数值模拟研究。通过随机分布难以渗透区域调节多孔颗粒内部的非均匀结构，分析颗粒内部非均匀结构对颗粒受力及其内外部流场演化的影响。结果表明，相对于内部结构均匀的多孔颗粒，颗粒的非均匀结构能够导致颗粒的升力和内部纵向传质的产生，升力和传质强度均随难以渗透区域含量wm增加而增加，随达西数(Da)增加呈先增加后减小的趋势。难以渗透区域的存在还导致颗粒后方尾涡在较低雷诺数(Re)下不再对称分布，且尾涡脱落的临界Re数降至约38，增强了流场的扰动强度。颗粒内部非均匀结构对颗粒受力和流场演化均有重要影响。

关键词: 多孔颗粒, 格子Boltzmann方程, 孔隙率, 升力, 尾涡

Abstract: The two-phase flow of porous particles widely exists in industrial processes. However, the internal structure of most porous particles is heterogeneous, which has been homogenized in previous studies and may affect the interaction between the particle and the fluid. Therefore, the volume-average macroscopic control equation based on the intrinsic phase average velocity was used to describe the fluid flow inside and outside the porous particles. Then, an improved lattice Boltzmann method (LBM) was used to solve the macroscopic control equation. Two-dimensional fluid flow around and through a heterogeneous porous particle was simulated numerically. By introducing difficult-to-permeable regions to adjust the internal porosity of porous particle, the effect of heterogeneity on the force of particle and evolution of flow field was simulated. The results showed that the heterogeneous structure could induce the lift force of the particle and realize the longitudinal mass transfer inside the particle compared to the homogeneous porous particle. Moreover, both the lift force and the mass transfer strength increased with the increase of the hard-to-penetrate area and Da number due to the asymmetric interaction between the particle and the fluid, but showed a peak value with Da number increasing to sufficiently large, mainly because of the effect of the internal structure diminished as the great quantity of fluids through the particle. On account of the lift force and mass transfer in the longitudinal, the presence of the hard-to-penetrate area also generated the wake vortex behind the particle to no longer be symmetrically distributed at a lower Re number, and to fall off at the Re number around 38, which enhanced the intensity of the disturbance of the flow field. In general, the existence of heterogeneous structure inside particle has an important influence on the force of the particle-fluid system and the evolution of the flow field, which is worth considering in future research.

Key words: porous particles, lattice Boltzmann equation, porosity, lift force, wake vortex