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The Effect of Swirl on Gas Velocity Decay in a Generic Annular Close-Coupled Nozzle

Published

Author(s)

Steven P. Mates, Frank S. Biancaniello, Stephen D. Ridder

Abstract

Introducing swirl into the gas flow generated by close-coupled nozzles has long been suggested as a means to improve melt disintegration near the nozzle tip. However, adding swirl may have unintended negative consequences on atomization performance by causing gas velocity to decay more quickly with distance from the nozzle exit. More rapid velocity decay can result in less effective secondary atomization far from the nozzle tip, potentially leading to coarser particles. Pitot pressure surveys were used to study the effect of swirl strength on the gas velocity decay rate of a generic annular close-coupled nozzle. Increasing swirl strength steadily reduced supersonic gas jet length compared to the no-swirl case, up to a maximum of 34% at the largest swirl strength tested (0.365). Swirl also displaces the peak gas velocity farther away from the centerline compared to the no-swirl case. The potential particle size coarsening due to the more rapid velocity decay caused by swirl may counteract the benefits swirl may provide near the nozzle exit. These counterbalancing effects must be accounted for in order to utilize swirl most effectively in the production of fine metal powders by gas atomization.
Proceedings Title
International Conference on Powder Metallurgy & Particulate Materials | 3rd | | TMS
Conference Dates
November 9-12, 2003
Conference Title
Powder Materials: Current Research and Industrial Practices Symposium

Keywords

atomization efficiency, atomization mechanisms, gas atomization, swirl

Citation

Mates, S. , Biancaniello, F. and Ridder, S. (2003), The Effect of Swirl on Gas Velocity Decay in a Generic Annular Close-Coupled Nozzle, International Conference on Powder Metallurgy & Particulate Materials | 3rd | | TMS (Accessed February 28, 2024)
Created December 1, 2003, Updated February 17, 2017