Hostname: page-component-77c89778f8-9q27g Total loading time: 0 Render date: 2024-07-20T08:23:23.889Z Has data issue: false hasContentIssue false
  • English
  • Français

Instability growth and fragment formation in air assisted atomization

Published online by Cambridge University Press:  06 April 2020

G. Singh ,
A. Kourmatzis Open the ORCID record for A. Kourmatzis [Opens in a new window] ,
A. Gutteridge  and
A. R. Masri
G. Singh
Affiliation:
School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW2006, Australia
A. Kourmatzis*
Affiliation:
School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW2006, Australia
A. Gutteridge
Affiliation:
School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW2006, Australia
A. R. Masri
Affiliation:
School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW2006, Australia
*
† Email address for correspondence: agisilaos.kourmatzis@sydney.edu.au
Get access Rights & Permissions [Opens in a new window]

Abstract

This paper reports an extensive study on the morphology of wave formation on the liquid core of atomizing sprays. The gas velocity, liquid jet velocity and liquid jet size are varied for two different fuels resulting in a range of liquid jet Reynolds numbers, aerodynamic Weber numbers and mass flux ratios. The liquid jet Reynolds number can be used to predict the initiation of jet instabilities, with coaxial air-flow velocity controlling their subsequent growth. A categorization of waves on the surface of the liquid according to their amplitude and wavelength has enabled (i) the identification of a threshold that leads to breakup, and (ii) the isolation of waves that lead to ligament formation from waves that result in droplets. The probability distribution of measured wavelength reasonably matches that of the ligament length, with no requirement for empirical constants. This confirms a direct link between interfacial instabilities and ligament formation in air assisted primary atomization.

JFM classification

Drops and Bubbles: Aerosols/atomization
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 892 , 10 June 2020 , A29
Copyright
© The Author(s), 2020. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Dumouchel, C. 2008 On the experimental investigation on primary atomization of liquid streams. Exp. Fluids 45 (3), 371–422.CrossRefGoogle Scholar
Engelbert, C., Hardalupas, Y., Whitelaw, J. H. & Launder, B. E. 1995 Breakup phenomena in coaxial airblast atomizers. Proc. R. Soc. Lond. A 451 (1941), 189–229.Google Scholar
Eroglu, H., Chigier, N. & Farago, Z. 1991 Coaxial atomizer liquid intact lengths. Phys. Fluids A 3 (2), 303–308.CrossRefGoogle Scholar
Faeth, G. M. 1996 Spray combustion phenomena. Symp. (Intl) Combust. 26 (1), 1593–1612.CrossRefGoogle Scholar
Faeth, G. M., Hsiang, L.-P. & Wu, P.-K. 1995 Structure and breakup properties of sprays. Intl J. Multiphase Flow 21, 99–127.CrossRefGoogle Scholar
Farago, Z. & Chigier, N. 1992 Morphological classification of disintegration of round liquid jets in a coaxial air stream. Atomiz. Sprays 2 (2), 137–153.Google Scholar
Fuster, D., Matas, J.-P., Marty, S., Popinet, S., Hoepffner, J., Cartellier, A. & Zaleski, S. 2013 Instability regimes in the primary breakup region of planar coflowing sheets. J. Fluid Mech. 736, 150–176.CrossRefGoogle Scholar
Gordillo, J. M., Perez-Saborid, M. & Ganan-Calvo, A. M. 2001 Linear stability of co-flowing liquid–gas jets. J. Fluid Mech. 448, 23–51.CrossRefGoogle Scholar
Kourmatzis, A., Lowe, A. & Masri, A. R. 2016 Combined effervescent and airblast atomization of a liquid jet. Exp. Therm. Fluid Sci. 75, 66–76.Google Scholar
Kourmatzis, A. & Masri, A. R. 2015 Air-assisted atomization of liquid jets in varying levels of turbulence. J. Fluid Mech. 764, 95–132.CrossRefGoogle Scholar
Kourmatzis, A., Pham, P. X. & Masri, A. R. 2015 Characterization of atomization and combustion in moderately dense turbulent spray flames. Combust. Flame 162 (4), 978–996.CrossRefGoogle Scholar
Kourmatzis, A., Pham, P. X. & Masri, A. R. 2017 A two-angle far-field microscope imaging technique for spray flows. Meas. Sci. Technol. 28 (3), 035302.CrossRefGoogle Scholar
Lasheras, J. C. & Hopfinger, E. J. 2000 Liquid jet instability and atomization in a coaxial gas stream. Annu. Rev. Fluid Mech. 32 (1), 275–308.CrossRefGoogle Scholar
Lasheras, J. C., Villermaux, E. & Hopfinger, E. J. 1998 Break-up and atomization of a round water jet by a high-speed annular air jet. J. Fluid Mech. 357, 351–379.CrossRefGoogle Scholar
Lefebvre, A. H. 1980 Airblast atomization. Prog. Energy Combust. Sci. 6 (3), 233–261.CrossRefGoogle Scholar
Lin, S. P. & Reitz, R. D. 1998 Drop and spray formation from a liquid jet. Annu. Rev. Fluid Mech. 30 (1), 85–105.CrossRefGoogle Scholar
Lowe, A., Kourmatzis, A. & Masri, A. R. 2017 Turbulent spray flames of intermediate density: stability and near-field structure. Combust. Flame 176, 511–520.CrossRefGoogle Scholar
Marmottant, P. & Villermaux, E. 2004 On spray formation. J. Fluid Mech. 498, 73–111.CrossRefGoogle Scholar
Matas, J.-P. 2015 Inviscid versus viscous instability mechanism of an airwater mixing layer. J. Fluid Mech. 768, 375–387.CrossRefGoogle Scholar
Matas, J.-P., Delon, A. & Cartellier, A. 2018 Shear instability of an axisymmetric airwater coaxial jet. J. Fluid Mech. 843, 575–600.CrossRefGoogle Scholar
Matas, J.-P., Marty, S. & Cartellier, A. 2011 Experimental and analytical study of the shear instability of a gas–liquid mixing layer. Phys. Fluids 23 (9), 094112.CrossRefGoogle Scholar
Mayer, W. O. H. & Branam, R. 2004 Atomization characteristics on the surface of a round liquid jet. Exp. Fluids 36 (4), 528–539.CrossRefGoogle Scholar
Otto, T., Rossi, M. & Boeck, T. 2013 Viscous instability of a sheared liquid–gas interface: dependence on fluid properties and basic velocity profile. Phys. Fluids 25 (3), 032103.CrossRefGoogle Scholar
Pham, P. X., Kourmatzis, A. & Masri, A. R. 2017 Simultaneous volume-velocity measurements in the near-field of atomizing sprays. Meas. Sci. Technol 28, 115203.CrossRefGoogle Scholar
Shinjo, J. & Umemura, A. 2010 Simulation of liquid jet primary breakup: dynamics of ligament and droplet formation. Intl J. Multiphase Flow 36 (7), 513–532.CrossRefGoogle Scholar
Singh, G., Pham, P. X., Kourmatzis, A. & Masri, A. R. 2019 Effect of electric charge and temperature on the near-field atomization of diesel and biodiesel. Fuel 241, 941–953.CrossRefGoogle Scholar
Umemura, A. 2011 Self-destabilizing mechanism of a laminar inviscid liquid jet issuing from a circular nozzle. Phys. Rev. E 83, 046307.Google ScholarPubMed
Varga, C. M., Lasheras, J. C. & Hopfinger, E. J. 2003 Initial breakup of a small-diameter liquid jet by a high-speed gas stream. J. Fluid Mech. 497, 405–434.CrossRefGoogle Scholar
Villermaux, E. 1998 Mixing and spray formation in coaxial jets. J. Propul. Power 14 (5), 807–817.CrossRefGoogle Scholar