Experimental study on 3D bubble shape evolution in swirl flow

•A novel capturing method and a bubble shape reconstruction algorithm are introduced.•The three dimensional bubble shape in the cyclone separator was obtained for the first time.•The effects of swirl number, bubble diameter, Reynolds number and Morton number on the bubble performance are investigate...

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Bibliographic Details
Published in:Experimental thermal and fluid science 2019-04, Vol.102, p.368-375
Main Authors: Zhang, Tingting, Qian, Yalan, Yin, Junlian, Zhang, Botao, Wang, Dezhong
Format: Article
Language:English
Subjects:
3D bubble shape
Algorithms
Binocular vision
Bubbles
Cameras
Computational fluid dynamics
Deformation
Deformation effects
Evolution
Fluid dynamics
Fluid flow
Heat transfer
Hydrodynamics
Mass transfer
Morphology
Reynolds number
Separators
Swirl flow
Virtual binocular stereo vision
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Summary:•A novel capturing method and a bubble shape reconstruction algorithm are introduced.•The three dimensional bubble shape in the cyclone separator was obtained for the first time.•The effects of swirl number, bubble diameter, Reynolds number and Morton number on the bubble performance are investigated. Evolution of bubble shapes has been a topic that never fades with time due to its close relation with physical processes such as fluid dynamics, heat and mass transfer, which are of fundamental and practical interest. Bubbles in swirl flow, especially, deform severely and take on a wide variety of irregular shapes resulting in great difficulties to obtain their morphological changes. Aiming to solve this problem in a reliable way, a virtual binocular stereo vision (VBSV) platform is set up, in which one camera is able to function as two cameras with the help of four mirrors. Corresponding reconstruction algorithm that assumes each cross section along the height of bubble to be an ellipse is established to compute 3D bubble shape. The unique bubble morphological evolution laws in complex swirl flow are obtained for the first time and the effects of swirl number (S), bubble diameter (d), Reynolds number (Re) and Morton number (Mo) on bubble shapes are investigated separately. Experimental results indicate that an ellipsoid bubble will be squashed and elongated gradually, and it tends to evolve into cap-shaped and cashew-shaped when approaching separator axial centre zone. Moreover, bubbles can undergo more severe deformation with greater S, d, and Re, whereas bigger Mo on the other hand weakens the deformation effect.
ISSN:0894-1777
1879-2286
DOI:10.1016/j.expthermflusci.2018.12.007