Atomizers for molten metals: Macroscopic phenomena and engineering aspects

Atomizers for molten metals are used extensively for industrial and researc h purposes; however, the phenomena governing atomizer design - the interact ion between fluids and the pressure field developed - and performance are l ess understood. In this article, the phenomena governing confined and free- fall atomizer behavior and performance are studied to develop engineering r ules for atomizer design. The behavior and performance of confined and free-fall atomizers, such as l iquid flow rate and fineness of atomized powders, are strongly dependent on the aerodynamic pressure field (APF) developed in the atomization region. The aerodynamic pressure field defines the operational mode of an atomizer: aspirating, gravity/aspirating, or gravity. Confined atomizers can only op erate in aspirating mode, since the pressure field has a wide aspirating re gion. Free-fall atomizers can operate in either gravity or mixed gravity/ a spirating mode, since the pressure field exhibits a narrow aspirating regio n followed by a flat and low-pressurization one. A calculation methodology was developed on the basis of Lubanska's equation to evaluate the required gas flow, the total area of atomizer nozzles, the required aspiration, and the liquid delivery tube tip positions.