Unsteady numerical simulation of gas-liquid flow in dual chamber microbubble generator

Abstract

In this study, an unsteady Computational Fluid Dynamic (CFD) simulation due to the transient operation was employed to characterize the gas-liquid mixing process and the fluid flow characteristics at a dual chamber microbubble generator as a reference in the design process. Based on the results, CFD simulation can visualize the mixing process and the fluid characteristics of the two-phase gas-liquid flow in a dual chamber microbubble generator, in the extremely narrow time, even in order of 0.1 s. The self-suction mechanism of microbubble generator was formed due to the swirl flow of liquid in the area of the inner chamber, causing the vacuum pressure in the central axis of the nozzle. This phenomenon was visible when the gas in the suction pipe started to enter the inner chamber of microbubble generator due to the swirl flow of liquid and vacuum pressure on the central axis of the nozzle at the time of 0.1 to 0.4 s. The swirl flow of liquid of the inner chamber could be seen clearly from the direction of the fluid velocity due to the geometry of the inner chamber inlet. By a high speed of fluid vortex flow around the outlet of the microbubble generator, the fine gas bubbles would be formed in consequence of the supersaturated condition between gas and liquid.