Experimental evaluation of 3D printed Venturi-type Fine Bubble Generators with internal obstacles

Abstract

The generation of Fine Bubbles (FB) using Venturi-type nozzles has been researched experimentally and mathematically using CFD simulations. Nevertheless, little has been discussed about the addition of obstacles in the convergent or divergent parts of the nozzle. Therefore, this research evaluates the performance of six fine bubble generation nozzles that were designed using cloud-based 3D modeling software and 3D printing. The designed nozzles were evaluated in terms of macroscopic features measured through oxygen gas absorption experiments and microscopic features such as size distribution and zeta potential measurements. Moreover, two indexes were proposed based on the gas absorption dynamic responses. These indexes were included in three objective functions that can be solved as mono-objective or multi-objective optimization problems. The nozzles with the best performance were evaluated regarding size distribution and zeta-potential. The results showed that installing obstacles in the divergent part of the nozzle attained higher gas absorption, smaller size of ultra fine bubbles (UFB), and more negative zeta potential.