欢迎访问过程工程学报, 今天是

过程工程学报 ›› 2024, Vol. 24 ›› Issue (3): 297-314.DOI: 10.12034/j.issn.1009-606X.223212

• 研究论文 • 上一篇    下一篇

中等雷诺数双分散悬浮系统流固曳力以及固固曳力

段凡1， 贺煊1， 周强1,2*   

  1. 1. 西安交通大学化学工程与技术学院，陕西 西安 710049 2. 西安交通大学动力工程多相流国家重点实验室，陕西 西安 710049
  • 收稿日期:2023-08-05 修回日期:2023-09-27 出版日期:2024-03-28 发布日期:2024-03-27
  • 通讯作者: 周强 zhou.590@mail.xjtu.edu.cn
  • 基金资助:
    双分散气固两相流中相间作用力的微尺度和介尺度模型研究

Fluid-particle and particle-particle drag forces in moderate-Reynolds-number bidisperse suspensions

Fan DUAN1,  Xuan HE1,  Qiang ZHOU1,2*   

  1. 1. School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China 2. State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China

  • Received:2023-08-05 Revised:2023-09-27 Online:2024-03-28 Published:2024-03-27
  • Contact: Qiang Zhou zhou.590@mail.xjtu.edu.cn

RichHTML

PDF

摘要： 采用一套全解析数值方法模拟了颗粒可自由移动的双分散悬浮系统，并对文献中已有的流固以及固固曳力公式的准确性进行了检验。模拟的参数范围为整体固含率0.1, 0.2, 0.3，粒径比1.5和2，小颗粒固含率占比0.1, 0.3, 0.5，颗粒-流体密度比10, 100, 500, 1000，整体颗粒雷诺数10, 20, 50。结果显示，对于流固曳力的预测，文献中已有的三类公式中静态均匀系统公式最准，动态悬浮系统公式次之，单分散扩展公式最差。进一步分析发现双分散悬浮系统流固曳力受局部固含率、颗粒相间滑移速度、颗粒拟温度、颗粒Stokes数以及颗粒微结构的影响。在这些因素的共同作用下，流固曳力随颗粒-流体密度比变化不明显，小颗粒相与大颗粒相的流固曳力差异小于静态均匀系统。对于固固曳力的预测，当颗粒-流体密度比等于10或100时，润滑力的作用会使碰撞次数在不同颗粒对之间分布不均，导致分子混乱假设不成立，基于颗粒动力学理论的公式远远高估固固曳力。

关键词: 流固曳力, 固固曳力, 双分散悬浮系统, 直接数值模拟, 颗粒动力学理论, 分子混乱假设

Abstract: A set of fully resolved numerical methods are employed to simulate the bidisperse suspensions where the particles are free to translate and rotate according to the effects of the surrounding fluid, and the fluid-particle and particle-particle drag relations in the literature are examined. Three overall solid volume fractions of 0.1, 0.2, and 0.3, two diameter ratios of 1.5 and 2, three small-particle-phase fractions of 0.1, 0.3, and 0.5, four particle-to-fluid density ratios of 10, 100, 500, and 1000, and three overall particle Reynolds numbers of 10, 20, and 50 are chosen. Simulation results show that, among the fluid-particle drag relations available in the literature, in terms of the model accuracy, the relations obtained from static homogeneous systems are the best, the next are those of dynamic suspensions, and the monodisperse drag extended relations are the worst. Based on the simulation data, a new fluid-particle drag relation that meets all physical requirements is proposed. Further analysis reveals that the fluid-particle drag of bidisperse suspensions is influenced by five factors, that is the local solid volume fraction, the slip velocity between different particle phases, the granular temperature, the particle Stokes number, and the particle microstructure. Under the action of these factors, the change of the fluid-particle drag is not significant as the particle-fluid density ratio varies, and the difference of the fluid-particle drag between small and large particle phases is smaller than that in static homogeneous systems. For the particle-particle drag, when the particle-fluid density ratio equals 10 or 100, the collision numbers are unevenly distributed between different particle pairs because of the lubrication force. This uneven distribution of the collision numbers leads to the invalid of the assumption of molecular chaos, and for this reason, the particle-particle drag is highly overestimated by the relation derived from the kinetic theory of granular flow.

Key words: fluid-particle drag, particle-particle drag, bidisperse suspensions, direct numerical simulation, kinetic theory of granular flow, assumption of molecular chaos