Abstract
This is a brief report on the properties of round jets of different densities issuing into the ambient air. Different densities were obtained by premixing helium and air in various proportions. We show that these jets have two types of behaviour depending on the density ratio between the jet and the ambient fluids, one characterized by very sharp peaks in the power spectral density of the velocity in the near field of the jet, and another with broadened and much less prominant spectral peaks. We examine the possibility that the first state corresponds to absolute instability, and the second to convective instability. It appears that the nature of instability can be changed from absolute to convective by very simple means reminiscent of similar possibilities in low Reynolds number wakes of circular cylinders. Flow visualization reveals that the low-density jets intermittently breakdown, and spread spectacularly, beyond a certain small axial distance.
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References
Bers, A. 1975: Linear waves and instabilities. In: Physique des plasmas (eds. Dewitt, C.; Peyraud, J.), pp. 117–213. New York: Gordon and Breach
Betchov, R.; Criminale, W. O. 1966: Spatial instability of the inviscid jet and wake. Phys. Fluids 9, 359–362
Briggs, R. J. 1964: Electron-stream interaction with plasmas (Research Monograph no. 29). Cambridge/MA: MIT Press
Corrsin, S.; Uberoi, M. S. 1950: Further experiments on the flow and heat transfer in a heated turbulent air jet. Washington/DC, NACA Rep. 998
Drubka, R. E.; Nagib, H. M. 1981: Instabilities in near field of turbulent jets and their dependence on initial conditions and Reynolds number. Illinois Institute of Technology, Chicago/IL, Tech. Rep. AFOSR-TR-82
Eckmann, J.-P.; Ruelle, D. 1985: Ergodic theory of chaos and strange attractors. Rev. Mod. Phys. 57, 617–656
Freymuth, P. 1966: On transition in a separated laminar boundary layer. J. Fluid Mech. 25, 683–704
Gaster, M. 1968: Growth of disturbances in both space and time. Phys. Fluids 11, 723–727
Hennemann, K.; Oertel, H. 1987: Numerical simulation of the absolutely and convectively unstable wake. J. Fluid Mech. (in press)
Ho, C.-M.; Huerre, P. 1985: Perturbed free shear layers. Annu. Rev. Fluid Mech. 16, 365–424
Huerre, P.; Monkewitz, P. A. 1985: Absolute and convective instabilities in free shear flows. J. Fluid Mech. 159, 151–168
Koch, W. 1985: Local instability chracteristics and frequency determination of self-excited shear flows. J. Sound Vibr. 99, 53–83
Kyle, D. 1986: Absolute instability in variable density jets. Dept. of Mechanical Engineering, Yale University, New Haven/CT, Rep. 86/FM6
Kyle, D. 1988: Laser-induced fluorescence images of helium/nitrogen jets. Dept. of Mechanical Engineering, Yale University, New Haven/CT, Rep. 88FMDK1
Kyle, D.; Raghu, S.; Sreenivasan, K. R. 1987: Periodic and aperiodic phenomena in variable density jets. Amer. Phys. Soc. 40th Annu. Meeting, paper FD4
Monkewitz, P. A.; Sohn, K. D. 1988: Absolute instability in hot jets. To appear in A.I.A.A.J.
Morkovin, M. V.; Paranjape, S. V. 1971: On acoustic excitation of shear layers. Z. Flugwiss. 19, 328–335
Olinger, D. J.; Sreenivasan, K. R. 1988: Nonlinear dynamics of the wake of an oscillating cylinder. Phys. Rev. Lett. 60, 797–800
Ramshankar, R. 1986: Experiments on a temporal analog of spatially developing free shear flows. Yale University, New Haven/CT, Rep. 86FM5
Sreenivasan, K. R. 1985: Transition and turbulence in fluid flows and low dimensional chaos. In: Frontiers of fluid mechanics (eds. Davis, S. H.; Lumley, J. L.), pp. 41–67. Berlin, Heidelberg, New York: Springer
Sreenivasan, K. R.; Strykowski, P. J.; Olinger, D. J. 1987: Hopf bifurcation, Landau equation, and vortex shedding behind circular cylinders. In: Forum on unsteady flow separation, (ed. Ghia, K. N.), pp. 1–13. ASME publication FED, vol. 52
Stein, G. D. 1969: Design of a multipurpose wind tunnel. Rev. Sci. Instrum. 40, 1058–1061
Strykowski, P. J. 1986: The control of absolutely and convectively unstable shear flows. Ph.D. Thesis, Yale University, New Haven/CT
Strykowski, P. J.; Sreenivasan, K. R. 1985: The control of transitional flows. AIAA Paper no. 85-0555
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Sreenivasan, K.R., Raghu, S. & Kyle, D. Absolute instability in variable density round jets. Experiments in Fluids 7, 309–317 (1989). https://doi.org/10.1007/BF00198449
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DOI: https://doi.org/10.1007/BF00198449