Preliminary study on application of x-ray CT scanner to measurement of void fractions in steady state two-phase flows

Preliminary studies are made in order to apply an X-ray CT scanner to the measurement of cross-sectional distributions of void fractions in steady state two-phase flows. Using air-water flows in a horizontal U-shaped tube, results of CT scanner measurements are compared with those of the volumetric measurements with quick-closing valves and of hotfilm anemometer measurements. Studied are cross-sectionally averaged void fractions and void fraction profiles. The comparisons give good agreements. The effect of density fluctuations on the reconstruction of void fraction distributions in two-phase flows is also discussed. Consideration of the statistical fluctuation in the projection data for a stationary object gives the sufficient conditions required for the evaluation of the cross-sectional distribution of the scanning time-averaged void fraction in steady state two-phase flows. (author)