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Experiments in Fluids

, Volume 36, Issue 4, pp 528–539 | Cite as

Atomization characteristics on the surface of a round liquid jet

  • W. O. H. Mayer ✝
  • R. Branam
Original

Abstract

Fundamental mechanisms of liquid jet breakup are identified and quantified. The quality of the atomization of liquids is an important parameter of many technological processes and is, e.g. for fuels and propellants critical in defining engine performance. This investigation takes a look at the jet behavior for a single injector element to determine the influence of the injection conditions on a round liquid jet. The study focuses on the atomization of a liquid forming a classical spray. To adjust the relative velocity between the liquid jet and the gaseous ambient a wind tunnel-like coaxial flow configuration was used. This made it possible to distinguish between effects of aerodynamic forces, chamber pressure and jet velocity, which determine the liquid Reynolds number and thereby the internal jet turbulence. Shadowgraphy and a novel image-processing approach was used to determine the jet surface characteristics: wavelength and amplitude. The absolute injection velocity of the jet seems to affect the structures the most with an increasing velocity causing the wavelengths to be smaller. An increase in chamber pressure seemed to have little influence on the jet with no relative velocity between the gas and liquid jet, but increased the amplitude and drop formation frequency at other testing conditions with relative motion. The wave amplitude trends provide information about the likelihood of drop formation but are limited in maximum size due to this breakup phenomenon of the jet. The study of the direction of the relative velocity demonstrated that injector performance cannot simply be described by scalar geometrical and operational injection parameters (e.g., We , Re or Oh), but has to include the injection direction of the atomizing fluids in relation to each other and to the ambient (e.g., combustion chamber). The undisturbed jet length and the spread angle were investigated, and a correlation for the droplet separation position was proposed. The data led to an extended classification of liquid jet breakup regimes. Large wave instabilities were experimentally analyzed and compared with linear stability theory.

Keywords

Relative Velocity Chamber Pressure Aerodynamic Force Weber Number Droplet Formation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

A

amplitude, frontal surface area

cf

viscous drag coefficient

cD

form drag coefficient

d

jet diameter

l

length

\( \hat{m} \)

lognormal parameter

N

sample size

Oh

Ohnesorge number, viscosity-to-surface tension force ratio

P

pressure

Re

Reynolds number, inertial-to-viscous force ratio

s

standard deviation

S

exposed surface area of jet

u

velocity in the axial (jet) direction

We

Weber number, inertial-to-surface tension force ratio

x ̄

average value, lognormal mean value

φ

diameter

λ

wavelength

ρ

density

μ

laminar viscosity, ^ lognormal parameter

ν

kinematic viscosity

σ

surface tension, ^ lognormal parameter

Subscripts and superscripts

o

centerline condition, outer diameter

d

based on jet diameter

i

inner, series counter

l

liquid

g

gas

properties in the chamber away from jet flow

Notes

Acknowledgements

This work was supported by the Federal Ministry of Education and Research (BMBF) under contract number 50TT9627 (Project TEKAN). The project was accomplished in the frame of the SPP, ‘Atomization and Spray Processes’ under the guidance of DFG (Deutsche Forschungsgemeinschaft). R. Branam is a guest scientist from the U.S. Air Force Research Laboratory.

References

  1. Castleman RA, Jr, (1932) The mechanism of the atomization accompanying solid injection. NACA Report 440Google Scholar
  2. Chehroudi B, Talley D, Coy E (1999) Initial growth rate and visual characteristics of a round jet into a sub- to supercritical environment of relevance to rocket, gas turbine, and diesel engines. AIAA paper number 99-0206, 37th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 11–14 January 1999Google Scholar
  3. Czerwonatis N, Eggers R (1999) Strahlzerfall und Tropfenwiderstand in Verdichteten Gasen. Tagungsband Spray ‘99, 3:1–8. 5th Workshop über Techniken der Fluidzerstäubung und Untersuchungen von Sprühvorgängen, Bremen, 1999Google Scholar
  4. Dimotakis PE (1986) Two-dimensional shear-layer entrainment. AIAA J 24:1791–1796Google Scholar
  5. Eroglu H, Chigier N (1991) Wave characteristics of liquid jets from airblast coaxial atomizations. Atomization Sprays 1:349–366Google Scholar
  6. Farago Z, Chigier N (1992) Morphological classification of disintegration of round liquid jets in a coaxial air stream. Atomization Sprays 2:137–153Google Scholar
  7. Hoyt JW, Taylor JJ (1977) Waves on water jets. J Fluid Mech 83:119–127Google Scholar
  8. Lefebvre AH (1989) Atomization and sprays. Hemisphere, New YorkGoogle Scholar
  9. Levich V (1962) Physiochemical hydrodynamics. Prentice Hall, Englewood Cliffs, NJGoogle Scholar
  10. Mayer WOH (1995) Coaxial liquid atomization with regard to atomization and mixing of propellants in rocket engines. European Space Agency Report ESA-TT-1334Google Scholar
  11. Mayer W (1994) Coaxial atomization of a round liquid jet in a high speed gas stream: a phenomenological study. Exp Fluids 16:401–410Google Scholar
  12. Mayer W, Branam R, Telaar J, Schneider G, Hussong J (2001) Characterization of cryogenic jet at supercritical pressures. AIAA paper number 2001-3275, 37th AIAA/ASME/ASEE Joint Propulsion Conference and Exhibit, Salt Lake City, UT, 9–11 July 2001 Google Scholar
  13. Mayer W, Schik A, Vieille B, Chaveau C, Goekalp I, Talley D, Woodward R (1998) Atomization and breakup of cryogenic propellants under high-pressure subcritical and supercritical conditions. J Propulsion Power 14:835–842Google Scholar
  14. Ohnesorge W (1937) Die Bildung von Tropfen aus Düsen beim Zerfall flüssiger Strahlen. Z.V.D.I, Band 81, Nr. 16, Google Scholar
  15. Papamoschou D, Roshko A (1988) The compressible turbulent shear layer: an experimental study. J Fluid Mech 197:453–477Google Scholar
  16. Reitz R (1978) Atomization and other breakup regimes of a liquid jet. Dissertation, Princeton University, Princeton, NJGoogle Scholar
  17. Reitz RD, Bracco FV (1982) Mechanism of atomization of a liquid jet. Phys Fluids 25:1730–1741CrossRefGoogle Scholar
  18. Schiller L (1922) Untersuchungen ueber Laminare und Turbulente Stroemung, VDI Forschungsarbeit, vol. 248Google Scholar
  19. Sterling AM, Sleicher CA (1975) The instability of capillary jets. J Fluid Mech 68:477–495Google Scholar
  20. Taylor JJ, Hoyt JW (1983) Water jet photography—techniques and methods. Exp Fluids 1:113–120Google Scholar
  21. Wu PK, Tseng LK, Faeth GM (1992) Primary breakup in gas/liquid mixing layers for turbulent liquids. Atomization Sprays 2:295–317Google Scholar

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • W. O. H. Mayer ✝
    • 1
  • R. Branam
    • 1
  1. 1.German Aerospace CenterDLR LampoldshausenHardthausenGermany

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