Ultrasonic atomization is a process that uses ultrasound waves to create tiny droplets from a liquid.
As per study Particle diameter d is
ρ and σ are respectively the density and surface tension of the atomized fluid and
f is a vibration frequency. Particle diameter also depends on Weber, Ohensorge and intensity number.
A liquid film is placed on a smooth surface that vibrates perpendicularly to the surface. The liquid absorbs some of the vibrational energy and creates waves called capillary waves. When the amplitude reaches a critical level, the waves collapse and eject tiny drops of liquid.
The amplitude of vibrations at 10 um is too small to induce atomization of liquids with parameters similar to water. After a time of 0.0119 [s], the liquid layer does not atomize, it only agglomerates into larger droplets with a thickness of approx(87 μm).
The amplitude necessary for the process of initiating atomization is about 60–70% higher than theoretically predicted. As the frequency increases to 22 kHz, the amplitude necessary to start the atomization process decreases to about 2 μm and then increases linearly to about 3 μm.
Droplet diameter (in micrometer): Water(36.3), Al(49.6), Zn(34.8), Steel(52.1) observed in study.
The droplets do not always atomize in the direction perpendicular to the vibrating surface and to the surface of the liquid; their trajectory is changed by the forces of coherence.
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