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Experimental Study of Two-Phase Flow Structure in Churn-Turbulent to Annular Flows
Experimental Thermal and Fluid Science
  • Qingzi Zhu
  • Guanyi Wang
  • Joshua P. Schlegel, Missouri University of Science and Technology
  • Yikuan Yan
  • Xiaohong Yang
  • Yang Liu
  • Mamoru Ishii
  • John R. Buchanan
Abstract

The local phase distribution of adiabatic air-water two-phase flow in churn-turbulent to annular flows was experimentally investigated using the Two-Sensor Droplet-Capable Conductivity Probe (DCCP-2). The experiments were performed in a 2.54 cm inner diameter vertical round pipe at downward flows. Twelve flow conditions in churn-turbulent to annular flows were chosen for the current study. The inlet superficial gas velocity ranged from 5.68 m/s to 17.19 m/s, and the inlet superficial liquid velocity ranged from 1.21 m/s to 2.64 m/s. The DCCP-2 is able to distinguish droplets, liquid ligaments, bubbles, and continuous gas. The radial profiles of volume fraction, frequency, axial interfacial velocity, and chord length of droplets, ligaments and bubbles were measured. The experimental results showed that gas volume fraction had a center-peak distribution, and the maximum gas volume fraction in centerline could exceed 95%. The volume fraction of droplets was very low, only on the order of 0.1%. Droplet concentration also showed a center-peak distribution. Both ligament and bubble volume fraction showed a near-wall peak distribution. The ligament volume fraction in the near wall region could reach 80%, which indicated the existence of a film region near the wall and likely includes surface waves on the film. The volume fraction profile of gas, droplets, ligaments, and bubbles showed the tomography structure in churn-turbulent to annular flows. The effects of flow conditions on phase distribution were also studied. An interesting feature was that both the increase of gas flux and the increase of liquid flux tended to increase the bubble volume fraction. The statistical distribution of droplet size was found to be invariant of radial position. The droplet velocity at centerline was generally larger than the superficial gas velocity, which can be attributed to the gravitational effects at downward flows.

Department(s)
Nuclear Engineering and Radiation Science
Keywords and Phrases
  • Annular flow,
  • Churn-turbulent flow,
  • Droplets,
  • Ligaments,
  • Local measurement
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2021 Elsevier, All rights reserved.
Publication Date
11-1-2021
Publication Date
01 Nov 2021
Disciplines
Citation Information
Qingzi Zhu, Guanyi Wang, Joshua P. Schlegel, Yikuan Yan, et al.. "Experimental Study of Two-Phase Flow Structure in Churn-Turbulent to Annular Flows" Experimental Thermal and Fluid Science Vol. 129 (2021) ISSN: 0894-1777
Available at: http://works.bepress.com/joshua-schlegel/94/