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Control of large-scale structure formation and vortex pairing using photoacoustic forcing

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Abstract

A method making use of the photoacoustic effect to control the formation of large scale structures in an axisymmetric ethylene jet at Reynolds numbers ranging between 2,000 and 2,550 is described. The experiment involved modulating the beam of a CO2 laser at Strouhal frequencies between 0.31 and 0.46 and focussing the beam into the gas jet. Time-averaged flow fields, perturbed with photoacoustic pulses are compared to that forced with a sinusoidal acoustic excitation and the results of a parametric study of the photoacoustic forcing are presented. Perturbations, achieved by laser heating the gas molecules are shown to force the flow into the jet-column fundamental and harmonic mode and to enhance vortex pairing. Time-averaged merging events at different phases of the process are displayed.

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References

  1. Bechert, D. W.; Pfizenmaier, E. 1978: Amplification of jet noise by a higher mode acoustical excitation. AIAA J. 15, 1268–1271

  2. Becker, H. A.; Massaro, T. A. 1968: Vortex evolution in a round jet. J. Fluid Mech. 31, 435–448

  3. Brown, G.; Roshko, A. 1974: On density effects and large structure in tubulent mixing layers. J. Fluid Mech. 64, 775–816

  4. Crow, S. C.; Champagne, F. C. 1971: Orderly structure in jet turbulence. J. Fluid Mech. 48, 547–591

  5. Fourguette, D. C.; Long, M. B. 1983: Highly localized pressure perturbations induced by laser absorptive heating in the shear layer of a gas jet. Opt. Letters 8, 605–608

  6. Heavens, S. N. 1980: Vsiualization of the acoustic excitation of a subsonic jet. J. Fluid Mech. 100, 185–192

  7. Ho, C. M.; Huang, L. S. 1982: Subharmonics and vortex merging in mixing layers. J. Fluid Mech. 119, 443–473

  8. Liu, J. T. C. 1989: Coherent structures in transitional and turbulent free shear flows. Annu. Rev. Fluid Mech. 27, 285–315

  9. Maestrello, L.; Bayliss, A.; Turkel, E. 1981: On the interaction of a sound pulse with the shear layer of a axisymmetric jet. J. Sound Vib. 74, 281–301

  10. Ng, T. T.; Bradley, T. A. 1988: Effect of multifrequency forcing on the near-field development of a jet. AIAA J. 26, 1201–1207

  11. Rayleigh, Lord 1884: Acoustical observations. Philos. Mag. 17, 188–194

  12. Winant, C. D.; Browant, F. K. 1974: Vortex pairing: the mechanism of turubulent mixing-layer at moderate Reynolds number. J. Fluid Mech. 63, 237–255

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Fourguette, D.C., Winter, M. Control of large-scale structure formation and vortex pairing using photoacoustic forcing. Experiments in Fluids 10, 157–160 (1990). https://doi.org/10.1007/BF00215024

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Keywords

  • Vortex
  • Reynolds Number
  • Flow Field
  • Parametric Study
  • Scale Structure