Experimental Study on Scale-up of a Venturi Microbubble Generator

Abstract

Due to the simple and inexpensive features, a venturi microbubble generator has been focused on and widely investigated in recent years. For industrial applications, the present study explores the scale-up of the venturi microbubble generator using a geometrical similarity scaling-up method. Based on the Dth 3.0 generator, two scaling-up experiments are carried out respectively with twice and 81 times the throat cross-sectional area of the Dth 3.0 generator. The sizes of the microbubbles generated are measured by image analysis and used as the reference index to evaluate the scaling-up effect. Using the data from the Dth 3.0 generator, a correlation of microbubble Sauter diameter vs gas velocity and liquid velocity is established and used as the benchmark to evaluate the scaling-up effect. In the two scaling-up experiments, the relative deviations of the measuring results from the predicted values of microbubble sizes are 18 and 21%, respectively. It can be concluded that the scaling-up rules, i.e., geometrical similarity and maintaining the liquid flow velocity at the throat larger than a critical value, are basically feasible.