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Primary breakup of a non-Newtonian liquid using a high-speed rotary bell atomizer for spray-painting processes

  • Bo Shen
  • Qiaoyan YeEmail author
  • Nico Guettler
  • Oliver Tiedje
  • Joachim Domnick
Article
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Abstract

The present contribution deals with numerical and experimental studies of the primary liquid breakup process using a high-speed rotary bell atomizer. The first part of the investigations focuses on the film formation on the distributor disk and the inner surface of the rotary bell. Numerical simulations using the volume-of-fluid approach were carried out. A non-Newtonian liquid that has shear-thinning behavior is used to investigate the effect of the viscosity on the initial wetting, the film formation process, and the film thickness distribution on the bell. A nonhomogeneous film structure is found on the inner surface of the rotary bell. This is also observed in experimental investigations using a high-speed camera. The second part focuses on the disintegration process of the paint liquid in the near bell region. As inlet conditions for the breakup simulations, the properties of the liquid film at the bell edge, i.e., film thickness, velocities, and apparent viscosity, resulting from the film formation simulations were applied. Two different liquid disintegrations in the near-field were found, which were also observed in experimental investigations using a high-speed camera. Furthermore, user-defined functions were compiled in ANSYS Fluent to uniquely identify and characterize droplets formed through the breakup process. In this way, droplet properties such as diameter, velocity, and position can be determined.

Keywords

Numerical simulation Rotary bell atomizer Film formation Ligament formation Liquid disintegration 

Notes

Acknowledgments

The present investigations were funded by the Bundesministerium für Wirtschaft und Energie under the support of the AiF Arbeitsgemeinschaft industrieller Forschungsvereinigungen (IGF-Project Number 19097N) and the Deutschen Forschungsgesellschaft für Oberflächenbehandlung e.V. The work has been also supported by the High-Performance Computing Center (HLRS) of the University of Stuttgart (German federal project: PbusRobe).We thank our colleagues from the Fraunhofer Institute for Manufacturing Engineering and Automation in Stuttgart who provided the experimental results that greatly assisted the present research.

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Copyright information

© American Coatings Association 2019

Authors and Affiliations

  1. 1.Fraunhofer Institute for Manufacturing Engineering and AutomationStuttgartGermany
  2. 2.University of Applied SciencesEsslingenGermany

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