Abstract
The performance of the constant temperature hot-wire anemometer as a local void fraction meter was studied with freely rising bubbles of air and vapour in ethanol. On-line measurements could be obtained in conjunction with a Schmidt circuit due to the sharp discrimination in the CTA voltage level between the two phases but the true void fraction was underestimated with a maximum deviation of 17% due to the deflection and distortion of bubbles by the action of surface tension.