Analysis of viscous fluid flow in a pressure-swirl atomizer using large-eddy simulation

•Numerical investigation of a large-scale, asymmetric pressure-swirl atomizer.•The simulations include inner nozzle flow and the onset of liquid film instability.•Various nozzle operation modes revealed by a Reynolds number sweep.•Liquid sheet types characterized for different Reynolds numbers.•Rich...

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Published in:International journal of multiphase flow 2019-04, Vol.113, p.371-388
Main Authors: Laurila, E., Roenby, J., Maakala, V., Peltonen, P., Kahila, H., Vuorinen, V.
Format: Article
Language:English
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Summary:•Numerical investigation of a large-scale, asymmetric pressure-swirl atomizer.•The simulations include inner nozzle flow and the onset of liquid film instability.•Various nozzle operation modes revealed by a Reynolds number sweep.•Liquid sheet types characterized for different Reynolds numbers.•Rich physics include vortex core, Dean vortices, sheet flapping and breakup. A computational fluid dynamics study is carried out on the inner nozzle flow and onset of liquid sheet instability in a large-scale pressure-swirl atomizer with asymmetric inflow configuration for high viscosity fluids. Large-eddy simulations (LES) of the two-phase flow indicate the unsteady flow character inside the nozzle and its influence on liquid sheet formation. A novel geometric volume-of-fluid (VOF) method by Roenby et al. (2016), termed isoAdvector, is applied for sharp interface capturing. We carry out a Reynolds number sweep (420 ≤ Re ≤ 5300) in order to investigate the link between the asymmetric inner nozzle flow and liquid sheet characteristics in laminar, transitional and fully turbulent conditions. Inside the nozzle, the numerical simulations reveal counter-rotating Dean vortices, flow impingement locations, and strong asymmetric flow features at all investigated Reynolds numbers. A helical, rotating gaseous core is observed when Re ≥ 1660. For laminar flow (Re=420), an S-shaped liquid film is observed, while the gas core presence at Re ≥ 1660 results in a hollow cone liquid sheet. For the intermediate value Re=830, the numerical simulations indicate a liquid sheet of mixed type. Consequences of the inflow asymmetry and Reynolds number to the uniformity of the injected liquid mass distribution and liquid sheet instability are pointed out.
ISSN:0301-9322
1879-3533
DOI:10.1016/j.ijmultiphaseflow.2018.10.008