Regularities of Bubble Formation at the Orifices of Submerged Perforated Sheets of Bubblers

Abstract

Based on literature data, an analysis of the modes of bubble formation at orifices immersed into the working environment of bubblers was carried out. The limits of applicability of calculated dependencies for determining the average bubble diameter between different areas of bubble formation on single orifices under conditions of constant gas flow into the bubble and constant gas pressure in the resulting bubble are given. When comparing calculated and experimental data on the sizes of the formed bubbles, it was found that, for the jet mode, there is no single calculation dependence that can at the same time quite accurately reflect the influence of both the orifice diameter and the physical properties of the two-phase medium on the bubble sizes. Despite the fact that a number of studies have shown experimentally and theoretically that the movement of liquid caused by bubbles floating above has a significant effect on the size of the bubbles, there are no verified calculation dependencies at present in the literature that take into account this effect over the entire range of gas flow through orifices of different diameters under different physical properties of the working environment. Based on the balance of forces acting at the moment of bubble separation, a model is proposed that also takes into account the dependence of the size of bubbles formed at the orifice by the movement of liquid caused by bubbles floating above. As a result of generalizing a large amount of experimental data available in the literature, a generalized dependence of the dimensionless average diameter of bubbles on the Bond, Froude, and Reynolds numbers was obtained for constant flow conditions for bubble and jet modes. The derived relationship is valid for orifices with different inner diameters and a wide range of physical properties of the working medium. The lower and upper limits of applicability of the formula for bubble and jet modes of bubble formation have been established.