Measuring and modeling detachment characteristics of onset bubbles via image processing

In this paper, image processing techniques are employed to investigate the growth and detachment characteristics of initial bubbles in vertical glass tubes. The study explores the effects of different continuous phases (water and Therminol (R) 66), nozzle diameters, air flow rates, and continuous phase liquid levels on the detachment diameter and shape of bubbles. Furthermore, based on the detachment characteristics obtained under various experimental conditions, a novel predictive model for bubble detachment diameter is established in both water and Therminol (R) 66. The results show that the bubble detachment diameter in the continuous phase therminol (R) 66 is larger than the bubble detachment diameter in water, and that the shape of the bubbles in therminol (R) 66 is close to spherical, with an ellipsoidal shape in water. With the increase in nozzle diameter and airflow, the bubble detachment diameter increases, and the shape is stretched in the vertical direction. With the increase in the continuous phase liquid level, the bubble detachment diameter decreases, and the shape change is not significant. In addition, the accuracy of the bubble detachment diameter prediction model was validated through experimental data. Compared with the experimental values, the average absolute errors were 5.04% and 5.11% in water and Therminol (R) 66, respectively. This study aims to investigate the characteristics of initial bubble growth and detachment, providing valuable references for nozzle design.