Void fraction and flow regime in adiabatic upward two-phase flow in large diameter vertical pipes

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • J. P. Schlegel
  • P. Sawant
  • S. Paranjape
  • B. Ozar
  • M. Ishii

Detail(s)

Original languageEnglish
Pages (from-to)2864-2874
Journal / PublicationNuclear Engineering and Design
Volume239
Issue number12
Publication statusPublished - Dec 2009
Externally publishedYes

Abstract

In pipes with very large diameters, slug bubbles cannot exist. For this reason, the characteristics of two-phase flow in large pipes are much different than those in small pipes. Knowledge of these characteristics is essential for the prediction of the flow in new nuclear reactor designs which include a large chimney to promote natural circulation. Two of the key parameters in the prediction of the flow are the void fraction and flow regime. Void fraction measurements were made in a vertical tube with diameter of 0.15 m and length of 4.4 m. Superficial gas and liquid velocities ranged from 0.1 to 5.1 m/s and from 0.01 to 2.0 m/s, respectively. The measured void fractions ranged from 0.02 to 0.83. Electrical impedance void meters at four axial locations were used to measure the void fraction. This data was verified through comparison with previous data sets and models. The temporal variation in the void fraction signal was used to characterize the flow regime through use of the Cumulative Probability Density Function (CPDF). The CPDF of the signal was used with a Kohonen Self-Organized Map (SOM) to classify the flow regimes at each measurement port. The three flow regimes used were termed bubbly, cap-bubbly, and churn flow. The resulting flow regime maps matched well with the maps developed previously through other methods. Further, the flow regime maps matched well with the criteria which were proposed based on Mishima and Ishii's (1984) criteria. © 2009 Elsevier B.V.

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Citation Format(s)

Void fraction and flow regime in adiabatic upward two-phase flow in large diameter vertical pipes. / Schlegel, J. P.; Sawant, P.; Paranjape, S. et al.
In: Nuclear Engineering and Design, Vol. 239, No. 12, 12.2009, p. 2864-2874.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review