Visualization method for cross-sectional two-phase flow structure during the condensation of steam in a tube

Andree Pusey, Dongeok Kim, Hyun Sik Park, Tae Soon Kwon, Hyungdae Kim

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Abstract: This paper describes an experimental investigation in which the cross-sectional two-phase flow structure during condensation of steam inside various inclined tubes was visualized using an axial-viewing technique and a high-speed camera. The two-phase flow structure was visualized along the axis of the condensation tube by locating the camera in front of the viewer that was fitted at the outlet of the tube where a short section of it was illuminated. This innovative technique permitted direct viewing into the flow and imaging of the cross-sectional area in a pipe of 16.55 mm inner diameter at atmospheric pressure and a saturation temperature of 100 °C. The downward inclination angle of the condensation tube in this study was varied from 3° to 75°, and three steam qualities, with values of 0.17, 0.34, and 0.78, were examined at the outlet of the pipe. A visualization test was conducted at a low steam mass flux of 3.43 kg/m2 s. Cross-sectional two-phase flow was clearly visible and identified easily over the range of inclination angles used; stratified-wavy flow was the most commonly observed flow pattern. Also, downward inclination had a significant effect on condensation parameters, such as void fraction, wetted angle, and bottom film thickness, which, in turn, showed that gravitational effects may improve condensation phenomena. Graphical abstract: [Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)591-605
Number of pages15
JournalJournal of Visualization
Issue number3
Publication statusPublished - 1 Aug 2017


  • Axial-viewing technique
  • Condensation
  • Inclination angle
  • Two-phase flow
  • Void fraction


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