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Instability Modal Behavior of the Acoustically Excited Impinging Plane Jet With a Small Cylinder

Published online by Cambridge University Press:  05 May 2011

Fei-Bin Hsiao*
Affiliation:
Institute of Aeronautics and Astronautics, National Cheng Kung University, Tainan, Taiwan 70101, R.O.C.
I-Che Hsu*
Affiliation:
Institute of Aeronautics and Astronautics, National Cheng Kung University, Tainan, Taiwan 70101, R.O.C.
Cheng-Chiang Hsu*
Affiliation:
Department of Aicraft Engineering, Air Force Institute of Technology, Kaohsiung, Taiwan 820, R.O.C.
*
*Professor
**Graduate student
***Assistant Professor
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Abstract

The Instability modal behavior of coherent structures in a jet-small cylinder impinging flow field is extensively studied by hot-wire anemometry measurements. The free jet is employed with a small cylinder of 3 mm in diameter located in the potential core region at the impinging length of L/H = 1.5 for the near field impingement and L/H = 4 for the far field impingement. The jet exit velocity is operated at 10 m/sec with the Reynolds number of 1.03 × 104 based on the nozzle exit width H = 15mm. The impinging jet is locally excited at the nozzle exit with varicose mode (m =0) and sinuous mode (m = 1) disturbances at the fundamental frequency of the natural jet flow. Data indicate that the jet flow is greatly altered and significantly enhanced by strengthening the coherent structures of the flow due to resonance according to the feedback mechanism. Although the original natural jet preferably exhibits the varicose mode, the strong sinuous mode is dominant in the flow field owing to the presence of the small cylinder in the potential core region. In the near field impingement, the wake region behind the cylinder preserves the pure sinuous mode to where the jet vortices merge and then mildly fades out. Whereas in the jet shear layer, the sinuous mode exists in the initial portion and gradually transforms to the varicose mode. In the far field impingement, the alternate mode dominates in each frequency stage in pure impinging case and the modal behavior follows the selected mode with the introducing acoustic waves in the acoustic excitation cases.

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Articles
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2004

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References

1.Crow, S. C. and Champagne, F. H., “Orderly Structure in Jet Turbulence,” J. Fluid Mech., 48, pp. 547591 (1970).CrossRefGoogle Scholar
2.Brown, F. K. and Roshko, A., “On Density Effects and Large Structure in Turbulent Mixing Layers,” J. Fluid Mech., 64, pp. 775816 (1974).CrossRefGoogle Scholar
3.Winant, C. D. and Browand, F. K., “Vortex Pairing—the Mechanism of Turbulent Mixing-Layer Growth at Moderate Reynolds Number,” J. Fluid Mech., 63, pp. 237255 (1974).Google Scholar
4.Ho, C. M. and Huang, L. S., “Subharmonics and Vortex Merging in Mixing Layers,” J. Fluid Mech., 119, pp. 443473 (1982).Google Scholar
5.Sato, H., “The Stability and Transition of a Two-Dimensional Jet,” J. Fluid Mech., 7, pp. 5380 (1960).CrossRefGoogle Scholar
6.Sato, H., “An Experimental Study of Nonlinear Interaction of Velocity Fluctuation in the Transition Region of a Two Dimensional Wake,” J. Fluid Mech., 44, pp. 745765(1970).CrossRefGoogle Scholar
7.Ho, C. M. and Gutmark, E., “Preferred Modes and the Spreading Rates of Jets,” Phys. Fluids, 26, pp. 29322938 (1983).Google Scholar
8.Strouhal, V., “On One Particular Way of Tone Generation,” Ann. Phys. Chem., 5, pp. 216251 (1878).Google Scholar
9.Von Karman, T., “Uber den Mechanismuss des Widersstandes den ein bewegter Korper in einen Flussigkeit Erfahrt,” Nachrichten der K. Gesellschaft der Wissenschaften zu Gottingen, pp. 547556 (1912).Google Scholar
10.Williamson, C. H. K., “Vortex Dynamics in the Cylinder Wake,” 28, pp. 477539 (1996).Google Scholar
11.Sondhaus, C., “Ueber die beim Ausstroemen der Luft entstehenden Tone,” Ann. Phys., 91, pp. 214240 (1854).Google Scholar
12.Chou, Y. W. and Hsiao, F. B., “Studying the Coherent Structures Interaction Between Jet and Wake Flows,” Transactions of the Aeronautical and Astronautical Society of the R.O.C., 28(4), pp. 305312 (1996).Google Scholar
13.Chou, Y. W., Hsiao, F. B. and Huang, J. M., “Vortex Dynamics and Energy Transport of a Plane Jet Impinging upon a Small Cylinder,” International Journal of Thermal and Fluid Science, 26(5), July 2002, pp. 445454 (2002).CrossRefGoogle Scholar
14.Hsiao, F. B., Chou, Y. W. and Huang, J. M., “The Study of Self-Sustained Oscillating Plane Jet Flow Impinging Upon a Small Cylinder,” Experiments in Fluids, 27(5), pp. 392399 (1999).CrossRefGoogle Scholar
15.Rockwell, D. and Naudascher, E., “Self-Sustained Oscillations of Impinging Free Shear Layers,” Ann. Rev. Fluid Mech., 11, pp. 6794 (1979).CrossRefGoogle Scholar
16.Hsiao, F. B., Hsu, I. C. and Hunag, J. M., “Smoke-Wire Visualization and Hot-Wire Measurement of an Acoustically Excited Impinging Plane Jet with a Small Cylinder,” Journal of Flow Visualization and Image Processing, 9(2), pp. 120 (2002).CrossRefGoogle Scholar
17.Hsiao, F. B., Hsu, I. C. and Huang, J. M., “Evolution of Coherent Structures and Feedback Mechanism of the Small Cylinder Impinging Plane Jet Flow under Acoustic Excitation,” to appear in Journal of Sound and Vibration (2004).CrossRefGoogle Scholar
18.Kibens, V., “Discrete Noise Spectrum Generated by an Acoustically Excited Jet,” AIAA Journal, 18, pp. 434441 (1980).CrossRefGoogle Scholar
19.Zaman, K. B. M. Q. and Hussain, A. K. M. F.“Turbulence Suppression in Free Shear Flow by Controlled Excitation,” J. Fluid Mech., 103, pp. 133159(1981).CrossRefGoogle Scholar
20.Strange, P. J. R. and Crighton, D. G., “Spinning Modes on an Axisymmetric Jets, Part 1,” J. Fluid Mechanics, 134, pp. 231245(1983).CrossRefGoogle Scholar
21.Hsiao, F. B. and Huang, J. M., “On the Mode Development in the Developing Region of a Plane Jet,” Phys. Fluids, 11(7), pp. 18471857 (1999).Google Scholar