Comparative Investigation on Wake Characteristics of an Vapor and Air Bubble Rising in a Vertical Narrow Rectangular Channel

Wake characteristics of a single vapor bubble rising in a vertical narrow rectangular channel were studied by PIV, and the effects of bubble diameter and inlet average fluid velocity on bubble rising velocity, wake structure and velocity profile were analyzed. In addition, wake characteristic of single vapor bubbles was compared with that of single air bubbles. Results showed that the terminal rising velocity of vapor bubbles as function of the bubble diameter was a little different from that of air bubbles. Effects of bubble diameter and inlet average velocity on the wake and position with maximum longitudinal velocity in the wake were all similar to that of air bubbles.