Analysis of viscous fluid flow in a pressure-swirl atomizer using large-eddy simulation. (April 2019)

• Record Type: Journal Article
• Authors: Laurila, E.; Roenby, J.; Maakala, V.; Peltonen, P.; Kahila, H.; Vuorinen, V.
• Is Part Of: International journal of multiphase flow. Volume 113(2019)
• Page Start: 371
• Page End: 388
• Publication Date: 2019-04
• Subjects: Pressure-swirl atomizer -- Primary atomization -- Hollow cone spray -- Two-phase flow -- Large-eddy simulation -- Volume-of-fluid method -- LES -- VOF -- isoAdvector; Multiphase flow -- Periodicals; Écoulement polyphasique -- Périodiques; Multiphase flow; Periodicals; 620.1064
• DOI: 10.1016/j.ijmultiphaseflow.2018.10.008
• Languages: English
• ISSNs: 0301-9322

Abstract

Highlights: 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. Abstract: 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 ( R e = 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 R e = 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.