Online ISSN : 1881-5790
Print ISSN : 0914-2843
ISSN-L : 0914-2843
Measurement of void fraction in bubbly flow with constant current method
Mitsumasa MURAKAMITadatsugu YOSHIKI
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1988 Volume 2 Issue 1 Pages 61-70


A device for constant current power source is proposed with which the electric current in upward two-phase flow channel is unaffected by the leakage current in downward flow channel. It is shown that the equivalent circuit for electrode is the parallel connection of series C-R and an electric noise cell. To eliminate the noises, a current with rectangular wave of 10KHz and a constant amplitude was used.
The electric resistance in a bubbly column is higher than that in a column in which a nonconductive rod with a same void fraction is inserted instead of bubbles. The coefficient, void fraction multiplier for current, is depend on both the void fraction and the bubble shape. The multiplier is estimated by assuming that bubbles are placed in the folw in the position of a face-centered cubic. The calibration curve obtained by the f.c.c. model is in good agreement with that determined by the experimental data in bubbly flow, and differ a little from that for a churn turbulent flow.
It is concluded that the constant current method is useful for the void faction measure ment in bubbly and churn turbulent flows.

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