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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

1997, Volume7

120 pages

Issue price - $75.00

LIGAMENT-CONTROLLED EFFERVESCENT ATOMIZATION

J. J. Sutherland
Thermal Sciences and Propulsion Center, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA

Paul E. Sojka
Maurice J. Zucrow Laboratories (formerly Thermal Sciences and Propulsion Center), School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA

Michael W. Plesniak
Maurice J. Zucrow Laboratories (formerly Thermal Sciences and Propulsion Center), School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA

ABSTRACT

The operating principles and performance of a new type of spray nozzle are presented. This nozzle, termed a ligament-controlled effervescent atomizer, was developed to allow consumer product manufacturers to replace volatile organic compound (VOC) solvents with water and hydrocarbon (HC) propellants with air, while meeting the following restrictions: that the spray mean drop size remain below 70 μm, that the atomizing air consumption be less than 0.009, and that atomizer performance be uncompromised by the increase in surface tension or by changes in viscosity. The current atomizer differs from previous effervescent designs through inclusion of a porous disk located immediately upstream of the nozzle exit orifice. The purpose of this disk is to control the diameter of ligaments formed at the injector exit plane. Atomizer performance is reported in terms of the spray Sauter mean diameter, with drop size data analyzed using a model developed from first principles. The model describes the spray formation process as the breakup of individual cylindrical ligaments subject to a gas stream. Ligament breakup length is obtained using the expression of Sterling and Sleicher [1]. Ligament diameter is estimated from manufacturer-supplied pore size data for the porous disk. The model correctly predicts the experimentally observed relationship between Sauter mean diameter and air-to-liquid ratio by mass, liquid surface tension, and liquid viscosity.