Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32579
Transient Analysis of Central Region Void Fraction in a 3x3 Rod Bundle under Bubbly and Cap/Slug Flows

Authors: Ya-Chi Yu, Pei-Syuan Ruan, Shao-Wen Chen, Yu-Hsien Chang, Jin-Der Lee, Jong-Rong Wang, Chunkuan Shih


This study analyzed the transient signals of central region void fraction of air-water two-phase flow in a 3x3 rod bundle. Experimental tests were carried out utilizing a vertical rod bundle test section along with a set of air-water supply/flow control system, and the transient signals of the central region void fraction were collected through the electrical conductivity sensors as well as visualized via high speed photography. By converting the electric signals, transient void fraction can be obtained through the voltage ratios. With a fixed superficial water velocity (Jf=0.094 m/s), two different superficial air velocities (Jg=0.094 m/s and 0.236 m/s) were tested and presented, which were corresponding to the flow conditions of bubbly flows and cap/slug flows, respectively. The time averaged central region void fraction was obtained as 0.109-0.122 with 0.028 standard deviation for the selected bubbly flow and 0.188-0.221with 0.101 standard deviation for the selected cap/slug flow, respectively. Through Fast Fourier Transform (FFT) analysis, no clear frequency peak was found in bubbly flow, while two dominant frequencies were identified around 1.6 Hz and 2.5 Hz in the present cap/slug flow.

Keywords: Central region, rod bundles, transient void fraction, two-phase flow.

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 614


[1] Qazi, M. K., Guido-Lavalle, G., Clausse, A., “Void fraction along a vertical heated rod bundle under flow stagnation conditions.” Nucl. Eng. Des., vol. 152, pp. 225-230, 1994.
[2] Kamei, A., Mizutani, Y., Hosokawa, S., Tomiyama, A., Murase, M., “Void Fraction in a Four by Four Rod Bundle Under a Stagnant Condition.”, vol. 4, pp.315-326, 2010.
[3] S. W. Chen, Y. Liu, T. Hibiki, M. Ishii, Y. Yoshida, I. Kinoshita, M. Murase, K. Mishima, “One-dimensional drift-flux model for two-phase flow in pool rod bundle systems,” International Journal of Multiphase Flow, vol.40, pp. 166-177, Apr. 2012.
[4] S. W. Chen, Y. Liu, T. Hibiki, M. Ishii, Y. Yoshida, I. Kinoshita, M. Murase, K. Mishima, “Experimental study of air–water two-phase flow in an 8 × 8 rod bundle under pool condition for one-dimensional drift-flux analysis,” International Journal of Heat and Fluid Flow, vol.33, pp. 168-181, Feb. 2012.
[5] S. W. Chen, M. S. Lin, F. J. Kuo, M. L. Chai, S. Y. Liu, J. D. Lee, B. S. Pei, "Experimental Investigation and Identification of the Transition Boundary of Churn and Annular Flows using Multi-Range Differential Pressure and Conductivity Signals", Applied Thermal Engineering, vol. 114, pp. 1275–1286, Sep. 2016.