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过程工程学报 ›› 2020, Vol. 20 ›› Issue (6): 638-645.DOI: 10.12034/j.issn.1009-606X.219283

• 流动与传递 • 上一篇    下一篇

表面活性剂虫状胶束流体中颗粒沉降负尾迹模拟

王治国, 张 恒, 蔺靖杰, 苏晓辉, 窦益华*   

  1. 西安石油大学机械工程学院,陕西 西安 710065
  • 收稿日期:2019-08-28 修回日期:2019-11-06 出版日期:2020-06-22 发布日期:2020-06-19
  • 通讯作者: 窦益华 yhdou@vip.sina.com
  • 基金资助:
    携砂黏弹性表面活性剂压裂液对管柱冲蚀的影响机理研究;极端工况下油套管柱强度分析及优化设计

Simulation of negative wake of particle settling in surfactant wormlike micellar fluid

Zhiguo WANG, Heng ZHANG, Jingjie LIN, Xiaohui SU, Yihua DOU*   

  1. School of Mechanical Engineering, Xi?an Shiyou University, Xi?an, Shaanxi 710065, China
  • Received:2019-08-28 Revised:2019-11-06 Online:2020-06-22 Published:2020-06-19

摘要: 颗粒在剪切稀释黏弹性表面活性剂形成的蠕虫状胶束流体中沉降时会产生负尾迹,负尾迹的形成对该种复杂流体与固体颗粒之间的相互作用具有重要影响。基于Giesekus本构方程,采用POLYFLOW软件模拟了黏弹性表面活性剂(Viscoelastic Surfactant, VES)蠕虫状胶束流体中单颗粒的沉降过程,分析了流体松弛时间和迁移因子对颗粒周围速度场及应力场的影响,重点研究了颗粒尾部速度负尾迹的产生原因及其对颗粒曳力的影响。结果表明,Giesekus本构方程能够描述VES流体的非线性剪切变稀行为和弹性导致的拉伸变形。流体弹性导致颗粒尾部产生较大的拉伸变形,剪切稀化和流体弹性的共同作用使颗粒尾部产生拉伸变形,导致负尾迹出现。表征流体弹性的De(黛博拉数)越大,流体拉伸黏度的Tr(特劳顿数)越小,负尾迹越长。负尾迹的出现使VES流体中颗粒所受曳力减小,沉降速度开始增加。模拟结果为此种流体的进一步应用提供了一定的研究基础。

关键词: 黏弹性表面活性剂流体, 颗粒沉降, Giesekus模型, 松弛时间, 负尾迹

Abstract: As a novel smart fluid, wormlike micellar fluids (WLMFs) have been used in the oil and gas enhancement and other process industry engineering. However, this fluid has an entangled wormlike micellar network and demonstrates complex viscoelastic rheology such as shear banding, extensional hardening and shear induced structure in flowing. It is urgent to investigate the particles settling and transport behavior in the complex flow of WLMFs. Amazingly, the negative wake may occur as the particle settling in this complex fluid, which means the fluid can flow at the opposite of particle settling direction. The negative wake of sphere particle settling in the WMFs plays an important role in the interaction between the fluid and particle. In this work, sphere particle settling behavior in viscoelastic surfactant (VES) wormlike micellar fluid was investigated by POLYFLOW based on the Giesekus constitutive equation. The effects of relaxation time and migration factor on the flow velocity and stress distribution around particles were analyzed. Furthermore, the mechanism of the negative wake in the rear of the particle and the effects on particle drag were investigated. The results showed that the Giesekus model could correctly interpret the behavior of non-linear shear thinning and extensional stress in the process of particle settlement in WLMFs. More extensional strain at the rear of particle was caused by the fluid elasticity. Furthermore, the negative wake occurred at the rear of particle for the interaction of fluid elasticity and shearing thinning. It can extend the downstream of particle settling with increasing the fluid elasticity (De number) and decreasing the ratio of extensional viscosity to zero shear viscosity (Tr, Trouton number). The negative wake promoted drag reduction and resulted in the increasing of particle setting velocity. The results can develop the theory of the multiphase flow of complex fluid and promote the application of viscoelastic surfactant wormlike micellar fluid.

Key words: viscoelastic surfactant fracturing fluid, particle settling, Giesekus constitutive model, relaxation time, negative wake