Influence of a Sound Field Parameters on Drops Dispersion at Liquids Acoustic Atomization

Y.Borisov, M.A.Mironov (Theoretical Laboratory, N.N.Andreev Acoustics Institute, Moscow, Russia)

e-mail: mironov@akin.ru

The results of experiments on ultrasonic atomization of water and alcohol-glycerine solutions in standing sound wave at a frequency range 3,7 - 20 kHz and sound levels within the limits of 156 - 178 dB are reported . The size of drops decrease at increase of sound frequency, its level and at increase of viscosity of atomized liquid. The attempt of theoretical explanation of these results with the help of the theory of a single initial drop static instability resulting in the drop flattening in a film and the subsequent dynamical instability of the film (modification of a Faraday effect) giving rise the fragmentation is given. The explanation consists in following. The liquid film in a sound field is thinning until the threshold of a dynamical instability will be surpassed. Increase of frequency and increase of viscosity of a liquid results in reduction of threshold thickness of a film. The increase of a sound-level results in more fast flattening of an initial drop and, probably, "jumping" of a dynamical instability threshold. According to the theory the size of fragments is proportional to depth of a film. Therefore all three factors: increase of frequency, increase of viscosity and increase of a sound level reduce thickness of a film and, as a consequence, reduce the size of fragments.


Section : 11