Drag Coefficient and Wake Volume of Single Bubbles Rising through Quiescent Liquids

Abstract

The behavior of single air bubbles rising through quiescent liquids, such as the shape, rising velocity and wake volume, is studied experimentally. The experiments which used seventeen kinds of aqueous glycerine solutions and glycerine-ethanol mixtures, are carried out in the Reynolds number range based on the equivalent spherical diameter 0.2-1000 and at the equivalent spherical diameter 0.2-1.8 cm. The wake volume is obtained from photographs using poster color.It is found that the bubble shape agrees with the equation of Tadaki et al., and the drag coefficient based on the major axis is correlated only with the Reynolds number based on the major axis. The effect of physical properties of liquids is not noticed. The volume ratio of the wake to the bubble is given as the function of the Reynolds number based on the equivalent spherical diameter and the Morton number, and the empirical equations are given.