Experimental measurement of the characteristics of surface flow generated by a bubble plume

The gas-liquid two-phase flow is available in the nature and has a wide range of industrial, material, chemical, mechanical, and environmental engineering applications. Knowledge of the bubble properties, including bubble velocity, bubble size, gas holdup, and specific interfacial area, is of considerable importance for the proper design and operation of bubble columns. Hoivever, the measurement of the bubble size, bubble velocity, and sjyecific interfacial area in two- and three-phase systems has always been a challenging problem. The technique of using a surface flow generated by a bubble plume is utilized as one of the effective ways to control and collect the surface floating substances in naval systems, lakes, seas, rivers, oceans, as loell as in various kinds of engineering processes handling a free surface. In the past, however, the detailed mechanism of the surface flow generation process has not been measured. The purpose of this paper is the necessity to understand the surface flow characteristics that depend on the gas flow rate, bubble size, and the internal two-phase flow structure of the bubble plume. In this pa/ter, the two-dimensional flow analysis based on flow visualization and image processing, including the particle image velocimetry (PIV) measurements, have been implemented in order to clarify the surface flow generation process in detail. The data are obtained for two kinds of visualized images: the first of the upper view of the surface flow and the second of the surface flow generation region under the free surface. The present results show that the surface velocity profile can be measured experimentally in good agreement with the numerical investigation that was carried out by the Eulerian-Lagrangian model presented in our earlier paper. The maximum xtelocity of the surface flow increases as small-size bubbles are supplied. The surface flow is effectively generated in the case of bubble plume compared to liquid jet flow because a distortion point appears in the vicinity of the surface. © 2015 by Begell House, Inc.