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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

NEW EXPERIMENTAL RESULTS ON DYNAMICS OF DROPLET CLUSTERS LEVITATING OVER THE LOCALLY HEATED WATER SURFACE

Alexander A. Fedorets
The University of Tyumen, 6 Volodarsky St, Tyumen, 625003, Russia

Leonid A. Dombrovsky
Joint Institute for High Temperatures, 17A Krasnokazarmennaya Str., Moscow, 111116, Russia; Tyumen State University, 6 Volodarsky Str., Tyumen, 625003, Russia

Dmitry V. Shcherbakov
Tyumen State University, 6 Volodarsky St, Tyumen, 625003, Russia

DOI: 10.1615/IHTC16.cod.022228
pages 2141-2146


KEY WORDS: Condensation, Measurement and instrumentation, Levitating droplets, Droplet cluster, Experiments, Fine technology

Abstract

The relatively stable clusters of regularly positioned small droplets formed over the locally heated water surface have been studied starting from the early paper by the first author. The life of a cluster appeared to be not long because of a growing of droplets due to condensation of steam and the final coalescence of large droplets with the substrate layer of water. However, further laboratory studies of biochemical processes in single droplets will be possible only in the case of their longer life. One way to stabilize the cluster suggested recently by the authors is an external infrared heating which prevents growing of droplets. A simple relation was found between the low required power of infrared radiation and the power of laser used to heat locally the water layer. The present paper is focused on a study of dynamics of droplet clusters at periodic changes in position or power of the heating laser beam. The resulting displacements of clusters along the water surface and their partial rebuilding at every change of laser irradiation parameters can be considered as an alternative way to slow the growth of droplets. In particular, it is suggested to use an oscillating power of the heating laser to stabilize the cluster. Obviously, the period of these oscillations is the most important parameter of the problem, whereas a small amplitude is not so important. The experiments showed that such a "rejuvenescence" procedure can be also used at laboratory conditions to prolong the life of levitating droplet clusters.

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