An investigation on bubble motion in liquid flowing through a rectangular Venturi channel

Equipments with Venturi structure have a broad application in various engineering fields. As an equipment for generating small bubbles, the Venturi-type bubble generator receives few investigations dealing with the fundamental hydraulic behavior involved. Current work mainly focused on movement of individual bubbles in a Venturi channel with a rectangular cross section. Visualized experiments were carried out to obtain motion parameters of individual bubbles with the help of a high speed camera and the method of Digital Image Analysis (DIA). The results showed that bubbles underwent a dramatic deceleration in the diverging section within a short distance, which was believed to play a key role in bubble breakup. An analysis of forces acting on a single bubble under current experimental condition indicated that the pressure gradient force and the added mass force were of great importance in decelerating the bubble, especially the former one which was significantly larger in magnitude than the others.