Flow regime characterization and void fraction measurement in a two-phase flow system by capacitance transducers

Abstract

The main purpose of this work is to extend the method of capacitance transducers to void fraction measurement and flow regime characterization in a two-phase flow system. The void fraction in an air-water system has been measured using the capacitance meter. Various flow regimes including bubbly, annular, wavy flows have been investigated. The superficial air and water velocity have been varied in the range of $0.0 \leqq {j_g} \leqq 0.395m/\sec$ and $0.0 \leqq {j_f} \leqq 10.115 m/\sec$ respectively and void fraction has been varied from zero to unity. The LCR meter is calibrated by both quick-closing valve method and theoretical calculation. From the experimental results, relationship between the measured relative capacitance and void fraction are obtained for annular and bubbly flows in the vertical test section, and for wavy flows in the horizontal test section under dynamic conditions. This result is compared with theoretical prediction. In addition, various parameters of the capacitance technique, such as (1) flow pattern, (2) strip-type electrode position with respect to a dielectric boundary, and (3) width to gap ratio of a pair of ring type electrodes are examined.