On the acoustic vaporization of micrometer-sized droplets

This paper examines the vaporization of individual dodecafluoropentane droplets by the application of single ultrasonic tone bursts. High speed video microscopy was used to monitor droplets in a flow tube, while a focused, single element transducer operating at 3, 4, or 10 MHz was aimed at the inter...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2004-07, Vol.116 (1), p.272-281
Main Authors: KRIPFGANS, Oliver D, FABIILLI, Mario L, CARSON, Paul L, FOWLKES, J. Brian
Format: Article
Language:English
Subjects:
Acoustics
Emulsions
Exact sciences and technology
Fluorocarbons - chemistry
Fundamental areas of phenomenology (including applications)
Lasers
Linear acoustics
Other topics
Physics
Transducers
Ultrasonics
Volatilization
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Summary:This paper examines the vaporization of individual dodecafluoropentane droplets by the application of single ultrasonic tone bursts. High speed video microscopy was used to monitor droplets in a flow tube, while a focused, single element transducer operating at 3, 4, or 10 MHz was aimed at the intersection of the acoustical and optical beams. A highly dilute droplet emulsion was injected, and individual droplets were positioned in the two foci. Phase transitions of droplets were produced by rarefactional pressures as low as 4 MPa at 3 MHz using single, 3.25 micros tone bursts. During acoustic irradiation, droplets showed dipole-type oscillations along the acoustic axis (average amplitude 1.3 microm, independent of droplet diameter which ranged from 5 to 27 microm). The onset of vaporization was monitored as either spot-like, within the droplet, or homogeneous, throughout the droplet's imaged cross section. Spot-like centers of nucleation were observed solely along the axis lying parallel to the direction of oscillation and centered on the droplet. Smaller droplets required more acoustic intensity for vaporization than larger droplets, which is consistent with other experiments on emulsions.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.1755236