Long-term effect of nanobubbles generated by turbulent flow through diamond-pattern notches on liquid properties, Results in Engine
Subin Han*, Seunghyeon Lee*, Young Soo Joung†
*These authors contributed equally to this work
Corresponding Authors: †E-mail: ysjoung@sm.ac.kr
Department of Mechanical Systems Engineering, Sookmyung Women's University, 100, Cheongpa-ro 47-gil, Yongsan-gu, Seoul, Republic of Korea
Abstract: In this work, we generated submicron bubbles (nanobubbles) using nanobubble generating nozzles (NBGNs) with diamond pattern notches. NBGNs are of great interest because they can generate nanobubbles within vortices at high flow rates without any external energy supply. However, the mechanism that generates nanobubbles has not been fully understood due to the lack of characterization of nanobubbles and quantitative evaluation of nanobubble effects. Here, for the first time, we revealed the presence of nanobubbles generated by NBGNs in turbulent flow using a high-speed camera with a high magnification lens and found the optimal flow conditions to generate nanobubbles. In addition, we characterized their number and size using a dynamic light scattering system to characterize the size distribution of nanobubbles quantitatively. Furthermore, based on the type and material of NBGNs, the effect of nanobubbles was experimentally investigated. As a result, we found that the fluid with nanobubbles produced by NBGN had low viscosity and high antibacterial properties due to the effect of nanobubbles. Moreover, the nanobubble effect was enhanced and lasted for several days. Finally, this study showed that NBGNs generated nanobubbles with long-term effects on bacterial viability and viscosity. We expect this study to serve as a basis for designing the optimal NBGN for the purpose.
Keywords: nanobubbles, microbubbles, antimicrobial property, liquid property change, bubble generator.