Dynamics of the Floating-Up of a Bubble Cluster
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 5, September, 2020
DYNAMICS OF THE FLOATING-UP OF A BUBBLE CLUSTER V. A. Arkhipov, S. A. Basalaev, K. G. Perfil′eva, and A. S. Usanina
UDC 532.529.6
Results of experimental investigation of the floating-up of a cluster of air bubbles in a viscous fluid by an optical method are presented. A setup has been developed for formation of a compact cluster of monodisperse bubbles with assigned diameter and volume concentration. It is shown that the velocity of the floating-up of a cluster of bubbles is higher than the velocity of the floating-up of a single bubble and depends on their number, diameter, and the distance between the bubbles. An empirical dependence of the resistance coefficient of a cluster of air bubbles floating up in glycerin on the Reynolds number has been obtained. Keywords: bubble cluster, resistance coefficient, optical method, experimental investigation. Introduction. Investigation of the laws governing the floating-up of a bubble cluster is of interest in solving a number of problems of technique and technology. The behavior of a liquid containing bubbles differs substantially from the behavior of homogeneous liquids under the conditions of different physical and physicochemical effects. These differences are used actively in industry in boiling, heat transfer in two-phase media, cavitation, frothing, and floatation. In a number of problems such as ignition of electric discharge in a liquid with the aid of specially created cavitation bubbles [1] and determination of the effect of surfactants and acoustic waves on the dynamics of bubble clusters [2–4], it is necessary to create a bubble cluster of assigned dimensions. Theoretical investigation of the motion of a set of solid particles was carried out in works [5, 6]. A diversity of experimental and theoretical works, whose review is given in [7], was devoted to the dynamics of floating-up of a single bubble. Experimental investigation of the dynamics of floating-up of a set of bubbles was carried out only for a chain of bubbles [8, 9], which is due to the difficulty of obtaining a compact spherical cluster of bubbles. In the present work, the results of experimental investigation (visualization) of the floating-up of a compact cluster of air bubbles in a viscous liquid with the use of an optical method are presented. To form a compact cluster of monodisperse bubbles a special experimental setup has been developed [10]. Experimental Method. The schematic of the experimental setup for investigating the dynamics of the floating-up of a cluster of monodisperse bubbles is presented in Fig. 1. A device for producing air bubbles 1 located at the bottom of reservoir 2 filled with a liquid is connected by pipe 3 with a compressed air reservoir 4 through a pressure microregulator 5 with control manometer 6 and pressure regulator 7. A vessel 8 connected with pipe 3 through a pressure microregulator 9 and T-joint 10 is intended for creating a positive pressure that prevents the working liquid fro
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