MECHANISMS OF SECONDARY ULTRASONIC LIQUID SPRAY

ZXFXYU

Abstract

Liquid atomization is the basis of various practical applications such as the production of pharmaceuticals, cosmetics, and food processing. In practice, it is often necessary to obtain an aerosol of high dispersion with sufficient productivity. However, creating an aerosol with maximum dispersion and high productivity is a difficult task. Some spray methods provide high dispersion but low throughput, while others provide sufficient throughput but generate large droplets. Secondary ultrasonic atomization can solve this problem by allowing non-contact atomization of droplets or jets using a powerful ultrasonic field. To do this, a stream of droplets or a stream of liquid previously generated in some way is directed into an ultrasonic emitter in the form of a hollow cylinder, in which an ultrasonic field is created. At a sufficiently high ultrasound intensity, conditions are realized for further fragmentation of droplets or destruction of liquid jets, and the output will be highly dispersed droplets. The productivity of such a process is limited only by the rate at which the liquid flow enters the secondary spraying device. This article discusses possible mechanisms of secondary ultrasonic atomization, proposes a mathematical model of this process, and finds patterns of the process depending on the defining parameters of the ultrasonic field and the physicochemical properties of the liquid. The following possible mechanisms for the destruction of jets and droplets have been proposed: direct destruction of droplets when they hit the front of an ultrasonic wave; cavitation mechanism of destruction of drops and jets. The dominant crushing mechanism depends on the parameters of the problem and, in turn, determines the minimum size of the resulting droplets. The free parameters of the model, which need to be determined experimentally, have been identified. The results of this work will help optimize the process of secondary ultrasonic atomization and improve liquid atomization technologies in various fields of application.