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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

2006, Volume16

159 pages

Issue price - $80.00

ATOMIZATION CHARACTERISTICS OF HIGH-SPEED ROTARY BELL ATOMIZERS

Joachim Domnick
Fachhochschule Esslingen, Kanalstrasse 33, D-73728 Esslingen, Germany

M. Thieme
Institut für Industrielle Fertigung und Fabrikbetrieb, Universität Stuttgart, Nobelstrasse 12, D-70569 Stuttgart, Germany

ABSTRACT

High-speed rotary bell atomizers are widely used in the painting industry for high-quality applications. They provide a highly uniform film thickness with reasonable transfer efficiency due to the additional electrostatic field supporting the droplet transport toward the target. The present contribution summarizes results related to high-speed rotary atomization of Newtonian fluids without electrical field. Water-sucrose-alcohol solutions have been used to vary viscosity and surface tension independently. The atomization processes observed could be divided into two distinct modes, that is, jet disintegration and transition from jet to sheet disintegration, the latter one being characterized by the presence of both radial and lateral fluid structures close to the bell edge. The separation line between these modes is expressed in terms of the We number and the flow number q. For jet disintegration, the Sauter diameter has been found to be a function of the three dimensionless parameters Re, We, and the flow number q. In the transition region from jet to sheet disintegration, the Sauter diameter is a function of the We number only. Finally, measured size distributions have been fitted by the three-parameter log-hyperbolic function and the location and shape of the distributions discussed as functions of the dimensionless parameters. Compared to other types of atomizers, it was found that the size distributions are not particularly narrow, as expected from the well-organized disintegration pattern, especially in the jet mode.