Abstract
This paper is concerned with the behavior of air bubble plumedriven by the source such as a diffuser plate.We measured the meanvelocities and streamwi se component of the turbulent fluctuations with a miniature propeller flow meter. In addition, the local volume fractions σ which are occupied by the air are measured with a conductivity probe. The conductivity probe is sensitive to changes in the conductivity of the mediumat the probe tip. As the bubbly water stream moves upward, it entrains morewater and spreads laterally. It is shown experimentaly that the stream whichis driven by the source has a minimum plume width at a cartain level near the source. Furthermore, it is found that the interaction of air bubbles play very important role in the region close to the source. On the basis of this fact, the diffusivity depending on the interaction of air bubbles is assumedproportional to the centerline fraction (σ0) n. The results of the analysisby the use of moment transformations of momentum and bouyancy equations are compared with our experimental data.
