化工学报 ›› 2019, Vol. 70 ›› Issue (12): 4565-4574.DOI: 10.11949/0438-1157.20190658

• 流体力学与传递现象 • 上一篇    下一篇

低Reynolds数下水平管降膜滴状流动的实验研究

柳山林(),牟兴森,沈胜强(),梁斌,包天杰,倪兵   

  1. 辽宁省海水淡化重点实验室,大连理工大学能源与动力学院,辽宁 大连 116024
  • 收稿日期:2019-06-12 修回日期:2019-09-21 出版日期:2019-12-05 发布日期:2019-12-05
  • 通讯作者: 沈胜强
  • 作者简介:柳山林(1992—),男,博士研究生,liushanlin@mail.dlut.edu.cn
  • 基金资助:
    国家自然科学基金重点项目(51936002)

Experimental study on droplet flow pattern of horizontal tube falling film flow with low Reynolds number

Shanlin LIU(),Xingsen MU,Shengqiang SHEN(),Bin LIANG,Tianjie BAO,Bing NI   

  1. Key Laboratory for Desalination of Liaoning Province, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China
  • Received:2019-06-12 Revised:2019-09-21 Online:2019-12-05 Published:2019-12-05
  • Contact: Shengqiang SHEN

摘要:

为了充分了解水平管降膜滴状流动现象,以水为实验流体,采用高速高清摄像仪对不同管距下水平管降膜滴状流动进行了可视化的实验研究。实验观察了低Reynolds数Re≤200、管间距s≤40 mm 范围内的管间滴状流动过程。根据流动形态的特征,将滴状流动划分为堆积滴状流、不完全滴状流、吊坠滴状流、完全滴状流和不完全回缩滴状流。依据实验结果,绘制了滴状流动形态分区图。提出了分离长度的概念,并讨论了流量对分离长度的影响。研究了低Reynolds数下液滴流动的滴落点间距与流量的关系。结果表明,滴状流的管间流动形态不仅受流量的影响,同时也受管间距的影响。分离长度随着Re的增大呈两段式线性增大。液滴流动的滴落点间距在Re≤100范围内随Re增大而减小,在100<Re≤200范围内趋于平稳。此外,分别建立了分离长度和滴落点间距与Re的关系式。

关键词: 水平管降膜, 滴状流动形态, 分离长度, 滴落点间距

Abstract:

To fully understand the drop-like flow phenomenon of the horizontal tube falling film, this paper uses water as the experimental fluid, and uses a high-speed high-definition camera to visualize the drop-shaped flow of the horizontal tube under different pipe spacings. The droplet flow in low Reynolds number Re≤200 and tube spacing s≤40 mm is observed. Based on the different flow characteristic, the droplet flow can be divided into accumulation droplet flow, incomplete droplet flow, pendant droplet flow, complete droplet flow and incomplete retracting droplet flow. According to the experimental results, the partition map of droplet flow is presented. The concept of separation length is proposed, and the effect of flow rate on separation length is discussed. The relationship between dropping site spacing and flow rate in droplet flow at low Reynolds number was studied. The results show that the flow pattern of droplet flow is influenced not only by flow rate but also by tube spacing. With the increase of tube spacing in Re≤120, the flow patterns between tubes are converted from accumulation droplet flow to incomplete droplet flow to pendant droplet flow, and to complete droplet flow. When 25 mm≤s≤40 mm, as the flow rate increases, the flow patterns are successively converted from incomplete droplet flow to pendant droplet flow, and to incomplete retracting droplet flow. The separation length increases linearly in two stages with the increase of Re. The growth rate in Re≤60 is smaller than it in 60<Re≤140. The correlation of separation length with Re is established in this paper. In addition, the dropping site spacing of droplet flow is investigated. The dropping site spacing decreases with the increase of flow rate in Re≤100, and remains stable in the range of 100<Re≤200. Meanwhile, the dropping site spacing of droplet flow with Re is established.

Key words: horizontal tube falling film, droplet flow pattern, separation length, dropping site spacing

中图分类号: