An integrative image measurement technique for dense bubbly flows with a wide size distribution

Ashish Karn, Christopher Ellis, Roger Arndt, Jiarong Hong

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


The measurements of bubble size distribution are ubiquitous in many industrial applications in chemical engineering. The conventional methods using image analysis to measure bubble size are limited in their robustness and applicability in highly turbulent bubbly flows. These flows usually impose significant challenges for image processing such as a wide range of bubble size distribution, spatial and temporal inhomogeneity of image background including in-focus and out-of-focus bubbles, as well as the excessive presence of bubble clusters. This article introduces a multi-level image analysis approach to detect a wide size range of bubbles and resolve bubble clusters from images obtained in a turbulent bubbly wake of a ventilated hydrofoil. The proposed approach was implemented to derive bubble size and air ventilation rate from the synthetic images and the experiments, respectively. The results show a great promise in its applicability for online monitoring of bubbly flows in a number of industrial applications.

Original languageEnglish (US)
Pages (from-to)240-249
Number of pages10
JournalChemical Engineering Science
StatePublished - Jan 7 2015

Bibliographical note

Funding Information:
The authors gratefully acknowledge the support by U.S. Department of Energy (Grant No. DE-EE0005416 ), ALSTOM Renewable Power Canada Inc. and the Office of Naval Research (Program manager, Dr. Ronald Joslin, Grant No. N000140910141). Help extended by undergraduate student Mr. Siyao Shao during the course of this work is also acknowledged and appreciated. Thanks are also due to Mr. Garrett Monson for his gas transfer measurements.

Publisher Copyright:
© 2014 Elsevier Ltd.


  • Bubble size distribution
  • Bubbly flow
  • Image analysis
  • Shadow image velocimetry
  • Synthetic bubble images
  • Ventilated hydrofoil wake


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