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Atomization and Sprays

Journal of the International Institutes for Liquid Atomization and Spray Systems

ISSN for PRINT: 1045-5110

Institutional price:	$787.00
Issues per year:	8

Best Paper Award Selection - Editorial Board Site

1996, Volume6

134 pages

Issue price - $75.00

MEASUREMENT OF THE EVAPORATION RATES OF CLOSELY SPACED FLOWING DROPLETS BY OPTICAL CAVITY RESONANCES

J. Christian Swindal
Department of Applied Physics and Center for Laser Diagnostics, Yale University, New Haven, Connecticut, USA

Gang Chen
Department of Applied Physics and Center for Laser Diagnostics, Yale University, New Haven, Connecticut, USA

Karl Scheschak
Department of Applied Physics and Center for Laser Diagnostics, Yale University, New Haven, Connecticut, USA

Richard K. Chang
Department of Applied Physics and Center for Laser Diagnostics, Yale University, New Haven, Connecticut, USA

Thomas A. Jackson
Air Force Aero-Propulsion Laboratory, Fuel and Lubrication Division, WRDC/POSF, Wright Patterson Air Force Base, Ohio, USA

ABSTRACT

The evaporation of liquid droplets in sprays can be altered by interactions between closely spaced particles. We discuss a nonintrusive optical measurement technique that is based on the optical cavity resonances of the droplets to determine droplet sizes and evaporation rates. The addition of small amounts of Rhodamine 6G laser dye into ethanol or ethanol/ acetone mixture droplets allows the droplets to lose at discrete wavelengths that correspond to the spectral positions of the droplet-cavity resonances. Measurements of the cavity resonance shift as the droplet evaporates permits determination of droplet size changes with a sensitivity of 1 nm in droplet radius change for droplets with a radius of 40 μm. We have determined the variation in evaporation rates among the leading and trailing droplets within a single segmented flowing stream, as well as between adjacent droplets that are flowing within a closely spaced 3 × 3 square array of continuous streams. Qualitative fluorescence images of the vapor produced by a continuous single stream of flowing acetone droplets demonstrate the existence of a vapor trail generated by the leading droplets flowing at 10 m/s.