THERMAL SCIENCE

International Scientific Journal

BINARY COLLISIONS AND COALESCENCE OF DROPLETS IN LOW-PRESSURE FUEL INJECTOR

ABSTRACT
The phenomena of binary collisions and coalescence of droplets was investigated from experimental studies but still are missing from real applications such as from fuel injector. The main purpose of the current study is to investigate the phenomena of binary collisions and coalescence of droplets from a practical port fuel injector. To accomplish this, direct microscopic images are taken from high speed video camera coupled with a long-distance microscope and Barlow lens using the backlighting method. Experimental optimization of the spatial resolution and the depth -of -field of the long-distance microscope and Barlow lens are achieved. Experimental results from the direct microscopic images are compared with predictions from empirical equations for different collision regimes. Droplet sizes and velocities of experimental coalescence droplets from collisions are compared with the values predicted by the equations. The main results of this study are: The probability of collision and coalescence is very low in a port fuel injector. The tangential velocity components of small droplets play an essential role in shape deformation during collisions and coalescence of the droplets. The previous published empirical equations to calculate dimensionless parameters, the Weber number, the droplet diameter ratio, and impact parameter are applicable to the coalescence of droplets in a port fuel injector.
KEYWORDS
PAPER SUBMITTED: 2019-11-20
PAPER REVISED: 2020-05-25
PAPER ACCEPTED: 2020-05-30
PUBLISHED ONLINE: 2020-06-07
DOI REFERENCE: https://doi.org/10.2298/TSCI191120185A
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2021, VOLUME 25, ISSUE Issue 3, PAGES [1963 - 1973]
REFERENCES
  1. Nobari, M. R., et al., Head‐on Collision of Drops - A Numerical Investigation, Physics of Fluids, 8 (1996), 1, pp. 29-42
  2. Ashgriz, N., Poo, J. Y., Coalescence and Separation in Binary Collisions of Liquid Drops, Fluid Mechanics, 221 (1990), Apr., pp. 183-204
  3. Orme, M., Experiments on Droplet Collisions, Bounce, Coalescence and Disruption, Progress in Energy and Combustion Science, 23 (1997) 1, pp. 65-79
  4. Qian, J., Law, C. K., Regimes of Coalescence and Separation in Droplet Collision, Journal Of Fluid Mechanics, 331(1997), May, pp. 59-80
  5. Brenn, G., The formation of Satellite Droplets by Unstable Binary Drop Collisions, Physics of Fluids, 13 (2001), 9, pp. 2463-2477
  6. Willis, K., Orme, M., Binary Droplet Collisions in a Vacuum Environment: An Experimental Investigation of the Role of Viscosity, Experiments in Fluids, 34 (2003), 1, pp. 28-41
  7. Roth, N., Droplet Collision Outcomes at High Weber Number, Proceeding, 21st Conference of Institute for Liquid Atomization and Spray Systems, Madison, Wis., USA, 2007, pp. 10-12
  8. Pan, K. L., et al., Binary Droplet Collision at High Weber Number, Physical Rev. E, 80 (2009), 3, 36301
  9. Kuschel, M., Sommerfeld, M., Investigation of Droplet Collisions for Solutions with Different Solids Content, Experiments in Fluids, 54 (2013), 2, 1440
  10. Planchette, C., et al., The Onset of Fragmentation in Binary Liquid Drop Collisions, Journal of Fluid Mechanics, 702 (2012), May, pp. 5-25
  11. Hinterbichler, H., et al., Ternary Drop Collisions, Experiments in Fluids, 56 (2015), 10, 190
  12. Post, S. L., Abraham, J., Modeling the Outcome of Drop-Drop Collisions in Diesel Sprays, International Journal of Multiphase Flow, 28 (2002), 6, pp. 997-1019
  13. Sommerfeld, M., Kuschel, M., Modelling Droplet Collision Outcomes for Different Substances and Viscosities, Experiments in Fluids, 57 (2016), 12, 187
  14. Planchette, C., Et Al., Colliding Drops as Coalescing and Fragmenting Liquid Springs, Journal of Fluid Mechanics, 814 (2017), Feb., pp. 277-300
  15. Li, J., Macroscopic Model for Head-On Binary Droplet Collisions in a Gaseous Medium, Physical Re-view Letters, 117 (2016), 21, 214502
  16. Strizhak, P. A., Characteristics of ‘Bounce' of Interacting Water Droplets, Technical Physics, 64 (2019), 6, pp. 796-801
  17. Jiang, Y. J., et al., An Experimental Investigation on the Collision Behaviour of Hydrocarbon Droplets, Journal of Fluid Mechanics, 234 (1992), Apr., pp. 171-190
  18. Pan, K. L., et al., Experimental and Mechanistic Description of Merging and Bouncing in Head-On Binary Droplet Collision, Journal of Applied Physics, 103 (2008), 6, 64901
  19. Estrade, J. P., et al., Experimental Investigation of Dynamic Binary Collision of Ethanol Droplets-A Model for Droplet Coalescence and Bouncing, International Journal of Heat and Fluid Flow, 20 (1999), 5, pp. 486-491
  20. Gao, T. G., et al., Collision Between an Ethanol Drop and a Water Drop, Experiments in Fluids, 38 (2005), 6, pp. 731-738
  21. Chen, R. H., Chen, C. T., Collision Between Immiscible Drops with Large Surface Tension Difference: Diesel Oil and Water, Experiments in Fluids, 41 (2006), 3, pp. 453-461
  22. Munnannur, A., Reitz, R. D., A New Predictive Model for Fragmenting and Non-Fragmenting Binary Droplet Collisions, International Journal of Multiphase Flow, 33 (2007), 8, pp. 873-896
  23. Zhang, P., Law, C. K., An Analysis of Head-On Droplet Collision with Large Deformation in Gaseous Medium, Physics of Fluids, 23 (2011), 4, 42102
  24. Krishnan, K. G., Loth, E., Effects of Gas and Droplet Characteristics on Drop-Drop Collision Outcome Regimes, International Journal of Multiphase Flow, 77 (2015), Dec., pp. 171-186
  25. Liu, D., et al., Collision Dynamics and Mixing of Unequal-Size Droplets," International Journal of Heat and Mass Transfer, 57 (2013), 1, pp. 421-428
  26. Mazloomi Moqaddam, A., et al., Simulation of Binary Droplet Collisions with the Entropic Lattice Boltzmann Method, Physics of Fluids, 28 (2016), 2, 22106
  27. Nikolopoulos, N., Bergeles, G., The Effect of Gas and Liquid Properties and Droplet Size Ratio on the Central Collision Between Two Unequal-Size Droplets in the Reflexive Regime, International Journal of Heat and Mass Transfer, 54 (2011), 1, pp. 678-691
  28. Nikolopoulos, N., et al., Off-Centre Binary Collision of Droplets: A Numerical Investigation, International Journal of Heat and Mass Transfer, 52 (2009), 19, pp. 4160-4174
  29. Nikolopoulos, N., et al., The Effect of Weber Number on the Central Binary Collision Outcome Be-tween Unequal-Sized Droplets, International Journal of Heat and Mass Transfer, 55 (2012), 7, pp. 2137-2150
  30. Focke, C., et al., Collision Between High and Low Viscosity Droplets: Direct Numerical Simulations and Experiments, International Journal of Multiphase Flow, 56 (2013), Oct., pp. 81-92
  31. Gotaas, C., et al., Effect of Viscosity on Droplet-Droplet Collision Outcome: Experimental Study and Numerical Comparison, Physics of Fluids, 19 (2007), 10, pp. 102-106
  32. Brazier-Smith, P. R., et al., The Interaction of Falling Water Drops: Coalescence. Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, 326 (1972), 1566, pp. 393-408.
  33. O'Rourke, P. J., Collective Drop Effects on Vaporizing Liquid Sprays, Ph. D. thesis, Los Alamos National Lab., Los Alamos, N. Mex., USA, 1981.

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