SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2018, Vol. 26 ›› Issue (9): 1803-1813.DOI: 10.1016/j.cjche.2018.04.002

• Fluid Dynamics and Transport Phenomena • 上一篇    下一篇

Hydrodynamics features of dispersed bubbles in the ventilated wake flow of a cylinder

Ning Mao1, Can Kang1, Wisdom Opare1,2, Yang Zhu1   

  1. 1 School of Energy and Power Engineering, Jiangsu University, Zhenjiang 21213, China;
    2 Faculty of Engineering, Takoradi Technical University, Takoradi, P. O. Box 256, Ghana
  • 收稿日期:2017-06-28 修回日期:2018-03-26 出版日期:2018-09-28 发布日期:2018-10-17
  • 通讯作者: Can Kang,E-mail address:kangcan@mail.ujs.edu.cn
  • 基金资助:

    Supported by the National Natural Science Foundation of China (51676087).

Hydrodynamics features of dispersed bubbles in the ventilated wake flow of a cylinder

Ning Mao1, Can Kang1, Wisdom Opare1,2, Yang Zhu1   

  1. 1 School of Energy and Power Engineering, Jiangsu University, Zhenjiang 21213, China;
    2 Faculty of Engineering, Takoradi Technical University, Takoradi, P. O. Box 256, Ghana
  • Received:2017-06-28 Revised:2018-03-26 Online:2018-09-28 Published:2018-10-17
  • Contact: Can Kang,E-mail address:kangcan@mail.ujs.edu.cn
  • Supported by:

    Supported by the National Natural Science Foundation of China (51676087).

摘要: An experimental study was conducted to investigate the 2D bubbly flow downstream of a cylinder. Sparsely distributed bubbles were produced using the ventilation method. The carrier flow was measured using the particle image velocimetry (PIV) technique. The shadow imaging technique was used to capture instantaneous bubbly flow images. An image-processing code was compiled to identify bubbles in acquired image, calculate the bubble equivalent diameter and the bubble velocity. The effects of Reynolds number and the flow rate of the injected air were considered. The result indicates that the carrier flow is featured by distinct flow structures and the wake region is suppressed as the upstream velocity increases. Regarding the bubbles trapped in the wake flow, the number of small bubbles increases with the upstream velocity. On the whole, the bubble velocity is slightly lower than that of the carrier flow. The consistency between small bubbles and the carrier flow is high in terms of velocity magnitude, which is justified near the wake edge. The difference between the bubble velocity and the carrier flow velocity is remarkable near the wake centerline. For certain Reynolds number, with the increase in the air flow rate, the bubble equivalent diameter increases and the bubble void fraction is elevated.

关键词: Bubble, Ventilation, Wake flow, PIV, Photography, Bubble size distribution

Abstract: An experimental study was conducted to investigate the 2D bubbly flow downstream of a cylinder. Sparsely distributed bubbles were produced using the ventilation method. The carrier flow was measured using the particle image velocimetry (PIV) technique. The shadow imaging technique was used to capture instantaneous bubbly flow images. An image-processing code was compiled to identify bubbles in acquired image, calculate the bubble equivalent diameter and the bubble velocity. The effects of Reynolds number and the flow rate of the injected air were considered. The result indicates that the carrier flow is featured by distinct flow structures and the wake region is suppressed as the upstream velocity increases. Regarding the bubbles trapped in the wake flow, the number of small bubbles increases with the upstream velocity. On the whole, the bubble velocity is slightly lower than that of the carrier flow. The consistency between small bubbles and the carrier flow is high in terms of velocity magnitude, which is justified near the wake edge. The difference between the bubble velocity and the carrier flow velocity is remarkable near the wake centerline. For certain Reynolds number, with the increase in the air flow rate, the bubble equivalent diameter increases and the bubble void fraction is elevated.

Key words: Bubble, Ventilation, Wake flow, PIV, Photography, Bubble size distribution