Ultrasonic atomization of liquids in drop-chain acoustic fountains

Julianna Simon, Oleg A. Sapozhnikov, Vera A. Khokhlova, Lawrence A. Crum, Michael R. Bailey

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

When focused ultrasound waves of moderate intensity in liquid encounter an air interface, a chain of drops emerges from the liquid surface to form what is known as a drop-chain fountain. Atomization, or the emission of micro-droplets, occurs when the acoustic intensity exceeds a liquid-dependent threshold. While the cavitation-wave hypothesis, which states that atomization arises from a combination of capillary-wave instabilities and cavitation bubble oscillations, is currently the most accepted theory of atomization, more data on the roles of cavitation, capillary waves, and even heat deposition or boiling would be valuable. In this paper, we experimentally test whether bubbles are a significant mechanism of atomization in drop-chain fountains. High-speed photography was used to observe the formation and atomization of drop-chain fountains composed of water and other liquids. For a range of ultrasonic frequencies and liquid sound speeds, it was found that the drop diameters approximately equalled the ultrasonic wavelengths. When water was exchanged for other liquids, it was observed that the atomization threshold increased with shear viscosity. Upon heating water, it was found that the time to commence atomization decreased with increasing temperature. Finally, water was atomized in an overpressure chamber where it was found that atomization was significantly diminished when the static pressure was increased. These results indicate that bubbles, generated by either acoustic cavitation or boiling, contribute significantly to atomization in the drop-chain fountain.

Original languageEnglish (US)
Pages (from-to)129-146
Number of pages18
JournalJournal of Fluid Mechanics
Volume766
DOIs
StatePublished - Jan 1 2015

Fingerprint

Fountains
atomizing
Atomization
ultrasonics
Ultrasonics
Acoustics
acoustics
Liquids
liquids
cavitation flow
Cavitation
Bubbles (in fluids)
capillary waves
bubbles
boiling
Boiling liquids
Water
water heating
water
Acoustic intensity

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Simon, J., Sapozhnikov, O. A., Khokhlova, V. A., Crum, L. A., & Bailey, M. R. (2015). Ultrasonic atomization of liquids in drop-chain acoustic fountains. Journal of Fluid Mechanics, 766, 129-146. https://doi.org/10.1017/jfm.2015.11
Simon, Julianna ; Sapozhnikov, Oleg A. ; Khokhlova, Vera A. ; Crum, Lawrence A. ; Bailey, Michael R. / Ultrasonic atomization of liquids in drop-chain acoustic fountains. In: Journal of Fluid Mechanics. 2015 ; Vol. 766. pp. 129-146.
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Simon, J, Sapozhnikov, OA, Khokhlova, VA, Crum, LA & Bailey, MR 2015, 'Ultrasonic atomization of liquids in drop-chain acoustic fountains', Journal of Fluid Mechanics, vol. 766, pp. 129-146. https://doi.org/10.1017/jfm.2015.11

Ultrasonic atomization of liquids in drop-chain acoustic fountains. / Simon, Julianna; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Crum, Lawrence A.; Bailey, Michael R.

In: Journal of Fluid Mechanics, Vol. 766, 01.01.2015, p. 129-146.

Research output: Contribution to journalArticle

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