A light attenuation technique for void fraction measurement of microbubbles

 A non-intrusive technique to measure the two-dimensional distribution of line averaged void fraction in a two-phase flow is discussed. A CCD camera is used to measure the attenuation of light as it passes through a bubbly flow, and this attenuation is related to the bubble concentration. The technique is appropriate for microbubbly flows where the bubble size is much smaller than the area imaged by a single pixel and where there are many bubbles attenuating light within each pixel. The measurement system is calibrated by using a two-dimensional line source microbubble plume as a reference. Revised: 30 March 2000/Accepted: 14 April 2000