Effect of shear-thinning on pressure-swirl atomization

  • Atomization of non-Newtonian liquids is an underexplored topic despite their numerous spray applications. Key spray characteristics in such processes are mean droplet size and size distribution. Several studies demonstrate that non-Newtonian shear-thinning liquids can narrow the droplet size distribution compared to Newtonian liquids, reducing the number of excessively small or large droplets. Various spray applications benefit from minimized occurrence of droplets outside the desired size range. This applies to atomizers in spray towers or agricultural sprays where too-small droplets are blown away while those too large are ineffectively used. In this study, several non-Newtonian dilute aqueous solutions with different degrees of shear-thinning were prepared by mixing Xanthan Gum or Sodium carboxymethyl cellulose with deionized water. Their performance was compared with Newtonian sprays (water and water − glycerol solution) of comparable shear viscosity at defined shear rates. A common pressure-swirl atomizer was used, and a range ofAtomization of non-Newtonian liquids is an underexplored topic despite their numerous spray applications. Key spray characteristics in such processes are mean droplet size and size distribution. Several studies demonstrate that non-Newtonian shear-thinning liquids can narrow the droplet size distribution compared to Newtonian liquids, reducing the number of excessively small or large droplets. Various spray applications benefit from minimized occurrence of droplets outside the desired size range. This applies to atomizers in spray towers or agricultural sprays where too-small droplets are blown away while those too large are ineffectively used. In this study, several non-Newtonian dilute aqueous solutions with different degrees of shear-thinning were prepared by mixing Xanthan Gum or Sodium carboxymethyl cellulose with deionized water. Their performance was compared with Newtonian sprays (water and water − glycerol solution) of comparable shear viscosity at defined shear rates. A common pressure-swirl atomizer was used, and a range of operational pressures along with varying viscosities allowed for examining the spraying process across a wide spectrum of Reynolds and Weber numbers. Velocity and size of droplets in the spray were measured simultaneously using a 1D phase Doppler anemometer. High-speed visualization was employed to track spray morphology and the breakup process. Cal� culations of the flow parameters inside the atomizer complemented these outcomes. Results show that varying viscosity and shear-thinning behaviour influence the flow dynamics from the liquid entry into the atomizer to the fully developed spray. Viscoelasticity complicates these processes further. The discharge occurs near the infinite-shear rate viscosity plateau, and its character depends, primarily on the flow conditions near the exit orifice. The shear-thinning and elasticity slightly affects liquid breakup, with production of more frequent and longer-lasting ligaments. Droplet size reduces with increasing pressure as expected, and this effect is more pronounced for non-Newtonians, the impact on the Relative span factor is inconsistent. Down� stream droplet size increases for all liquids due to coalescive droplet collisions, with the secondary breakup and evaporation being ineffective.show moreshow less

Export metadata

Additional Services

Search Google Scholar
Metadaten
Author:Jan Jedelsky, Selwyn Van der Laan, Ondrej Cejpek, Milan Maly, Martin Kadlec, Jiri Smilek, Pavel Strmiska, Ondrej Hajek, Dirk Sachsenheimer
DOI:https://doi.org/10.1016/j.ijheatmasstransfer.2025.127777
Parent Title (English):International Journal of Heat and Mass Transfer
Document Type:Article
Language:English
Date of first Publication:2025/09/17
Release Date:2025/10/23
Tag:Extensional viscosity; Non-Newtonian liquids; Pressure-swirl atomizer; Relative span factor; Shear viscosity; Shear-thinning liquids
Volume:255
Article Number:127777
Pagenumber:14
institutes:Fakultät für Angewandte Chemie
Research Themes:Materialien & Produktionstechnik
Licence (German):Creative Commons - CC BY - Namensnennung 4.0 International
Verstanden ✔
Diese Webseite verwendet technisch erforderliche Session-Cookies. Durch die weitere Nutzung der Webseite stimmen Sie diesem zu. Unsere Datenschutzerklärung finden Sie hier.