Bubbly jet impingement in different liquids

Abstract

The impingement of bubbly jets in distilled water and ethanol has been experimentally studied on ground. An experimental apparatus for the study of jet impingement on ground and inmicrogravity has been designed. The opposed-jet configuration with changeable orientation is used in order to study which is the better disposition to achieve an efficient mixing process. The impact angle between jets that can be changed from 0◦ (frontal collision) up to 90◦ (perpendicular collision). The impinging jets are introduced into a test tank full of liquid by means of two bubble injectors. The bubble generation method, insensitive to gravity level for low Bond numbers, is based on the creation of a slug flow inside a T-junction of capillary tubes of 0.7 mm of diameter. Bubble velocities at the injector outlet and generation frequencies can be controlled by changing gas and liquid flow rates. Individual bubble properties and coalescence events, as well as the whole jet structure are analyzed from the images recorded by a high speed camera. Bubble velocities are compared with the velocity field of a single-phase jet. Rate of coalescence between bubbles is found higher in ethanol than in water, creating a higher dispersion in bubble sizes.