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Multiphase Science and Technology
SJR: 0.153 SNIP: 0.222 CiteScore™: 0.26

ISSN Print: 0276-1459
ISSN Online: 1943-6181

Multiphase Science and Technology

DOI: 10.1615/MultScienTechn.v27.i1.20
pages 27-49

BUBBLE TRACKING IN BUBBLY GAS-LIQUID TWO-PHASE FLOW IN POROUS STRUCTURES

Marco Altheimer
Institute of Process Engineering, Swiss Federal Institute of Technology (ETH), Zürich, Sonneggstrasse 3, 8092 Zürich, Switzerland
Carmen Wälchli
Institute of Process Engineering, Swiss Federal Institute of Technology (ETH), Zürich, Sonneggstrasse 3, 8092 Zürich, Switzerland
Philipp Rudolf von Rohr
Institute of Process Engineering, Swiss Federal Institute of Technology (ETH), Zürich, Sonneggstrasse 3, 8092 Zürich, Switzerland

ABSTRACT

Bubble motion in a gas-liquid co-current flow through a porous structure is investigated. Bubble residence time, influence of the structure on the bubble motion, and influence of the buoyancy force acting on the bubble are determined to obtain a better understanding of the existing fluid dynamics in the porous structure. A variety of liquid flow rates (Re = 114-285) and volumetric transport fractions (? = 2.4, 3.2, and 4.1%) are taken into account. Measurements inside and at the outlet of the structure are conducted and compared. The bubble motion is captured in a shadow imaging process, and overlapping bubble shadows are obtained. Therefore, a bubble-tracking algorithm is presented for the tracking of overlapping bubble shadows obtained by shadow imaging. The algorithm's matching criterion is based on similitude and proximity, and validated by running synthetic images. Errors are estimated for varying gas holdup (bubble density) and bubble displacement between consecutive images. The influence of the frame rate on the tracking capability (matching of bubbles in consecutive images) and the underestimation of the bubble track by low temporal resolution are investigated.