Effects of Nozzle Geometry on Fine Bubble Generation and Surface Cleaning Performance

Fine bubbles have attracted attention in recent years due to their promising characteristics and extensive applications. One type of fine bubble generator, the Venturi tube, utilizes a sudden change in pressure inside the tube and is widely used due to its simple structure, high generation efficiency, and low power consumption. The volume of bubbles generated (generation yield) and their average diameter are key parameters in evaluating the performance of a Venturi tube generator, which depends on both the flow conditions and the geometric configuration of the generator. In this study, an oral irrigator incorporating fine bubble technology was developed, with a Venturi tube embedded in the irrigator for fine bubble generation. We designed Venturi tubes with various geometric configurations under different flow conditions to enhance fine bubble generation performance and cleaning efficiency through both experiments and numerical simulations. The results indicate that the generation performance and cleaning performance of fine bubbles are strongly influenced by the geometric parameters of the Venturi tube. Among the tested configurations, the Venturi tube with a divergent angle of 5° and a divergent length of 30 mm demonstrated the best performance.