Impact of Throat Diameter, Length, and Divergent Angle on Bubble Formation and Flow Characteristics in Venturi Microbubble Generators
DOI:
https://doi.org/10.15282/ijame.22.4.2025.7.0984Keywords:
Bubble formation, Throat diameter, Throat length, Divergent angle, Venturi, MicrobubbleAbstract
The design of a Venturi microbubble generator (VMBG) is crucial in influencing the size and distribution of produced microbubbles, which are essential in several industrial, medicinal, and environmental applications. This study examines the impact of three critical geometric parameters: throat diameter, throat length, and divergent angle, on the formation of bubbles and the characteristics of flow. A combination of experimental visualization using Particle Image Velocimetry and computational fluid dynamics simulations using the Euler–Lagrange approach with the realizable k-epsilon turbulence model was employed. Nine VMBG configurations were tested, with throat diameters of 8.5 mm, 12 mm, and 20 mm, throat lengths of 10 mm, 15 mm, and 30 mm, and divergent angles of 30°, 45°, and 60°. The findings showed that decreasing the throat diameter from 12 mm to 8.5 mm produced smaller and denser bubbles, resulting in an increase in flow velocity by 68% and vorticity by 30%. Results showed that smaller throat diameters (8.5 mm) increased flow velocities, turbulence, and vorticity, while longer throat lengths (30 mm) provided smoother fluid transitions. Larger divergent angles caused a significant drop in velocity, increased turbulence, and produced smaller bubble sizes. However, they also promoted bubble expansion and denser formation in the divergent section. Both throat diameter and throat length also played a crucial role in undergoing complete bubble formation stages. Experimental results, which were very similar to the computer results, verified the four stages of bubble formation: nucleation, expansion, coalescence, and breakdown. The study provides valuable insights for enhancing VMBG designs, enabling the creation of microbubbles with features suitable for specific applications.
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