Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-28T03:40:57.883Z Has data issue: false hasContentIssue false
  • English
  • Français

The free shear layer tone phenomenon and probe interference

Published online by Cambridge University Press:  12 April 2006

A. K. M. F. Hussain  and
K. B. M. Q. Zaman
A. K. M. F. Hussain
Affiliation:
Department of Mechanical Engineering, University of Houston, Texas 77004
K. B. M. Q. Zaman
Affiliation:
Department of Mechanical Engineering, University of Houston, Texas 77004
Get access Rights & Permissions [Opens in a new window]

Abstract

Free shear layer stability measurements with a hot wire revealed that the probe itself can trigger and sustain upstream instability modes like the slit jet-wedge edge tones. The flow fields associated with the free shear layer tones induced in axisym-metric and plane air shear layers by a hot-wire probe and by a plane wedge were then explored experimentally, and found to be different in many ways from the widely investigated jet edge tone phenomenon.

As many as four frequency stages have been identified, there being a fifth stage associated with the subharmonic attributed to vortex pairing in the free shear layer. No evidence of hysteresis could be found in the shear layer tone. In the interstage jump (i.e. bimodal) regions, the tone occurred in only one mode at a time while intermittently switching from one to the other. Frequency variations in each stage are shown to collapse on a single curve when non-dimensionalized with the initial momentum thickness θe or with the lip-wedge distance h, and plotted as a function of h/θe.

Phase average measurements locked onto the tone fundamental show that the phase velocity and wavelength of the tone-induced velocity fluctuation are essentially independent of the stage of tone generation; in each stage, both phase velocity and wavelength decrease with increasing frequency but undergo jumps at starts of new stages. The measured amplitude and phase profiles, as well as the variations of the shear tone wavenumber and phase velocity with the Strouhal number, show reasonable agreement with the predictions of the spatial stability theory. The wavelength λ bears a unique relation to h, this h, δ relation being different from the Brown-Curle equation for the jet edge tone.

Shear layer tones would be typically induced in near-field shear layer measurements involving invasive probes, and can produce misleading results. A method for determining the true free shear layer natural instability frequency is recommended.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 87 , Issue 2 , 26 July 1978 , pp. 349 - 383
Copyright
© 1978 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bilanin, A. J. & Covert, E. E. 1973 A.I.A.A. J. 11, 347.
Bishop, K. A., Ffowcs williams, J. E. & Smith, W. 1971 J. Fluid Mech. 50, 21.
Bolton, S. 1976 M.Sc. thesis, University of Southampton.
Bradshaw, P. 1966 J. Fluid Mech. 26, 225.
Browand, F. K. & Laufer, J. 1975 Turb. Liquids, Univ. of Missouri-Rolla, 5, 333.
Browand, F. K. & Weidman, P. D. 1976 J. Fluid Mech. 76, 127.
Brown, G. & Roshko, A. 1974 J. Fluid Mech. 64, 775.
Brown, G. B. 1937a Proc. Phys. Soc. 49, 493.
Brown, G. B. 1937b Proc. Phys. Soc. 49, 508.
Corcos, G. M. & Sherman, F. S. 1976 J. Fluid Mech. 73, 241.
Crow, S. C. & Champagne, F. H. 1971 J. Fluid Mech. 48, 547.
Curle, N. 1953 Proc. Roy. Soc. A 216, 412.
Dimotakis, P. E. & Brown, G. L. 1976 J. Fluid Mech. 78, 535.
Freymuth, P. 1966 J. Fluid Mech. 25, 683.
Hussain, A. K. M. F. 1970 Ph.D dissertation, Stanford University.
Hussain, A. K. M. F. 1977 Initial condition effect on free turbulent shear flows. Symp. Turbulence, Berlin.Google Scholar
Hussain, A. K. M. F. & Clark, A. R. 1977 Phys. Fluids 20, 1416.
Hussain, A. K. M. F. & Reynolds, W. C. 1972 J. Fluid Mech. 54, 241.
Hussain, A. K. M. F. & Thompson, C. A. 1975 Proc. 12th Ann. Meeting, Soc. Engng Sci., Univ. Texas (Austin), pp. 741–752.
Hussain, A. K. M. F. & Zaman, K. B. M. Q. 1975 Proc. 3rd Int. Symp. Trans. Noise, Univ. of Utah, pp. 314–326.
Hussain, A. K. M. F. & Zaman, K. B. M. Q. 1977 Controlled perturbations of circular jets. Symp. Turbulence, Berlin.Google Scholar
Hussain, A. K. M. F. & Zedan, M. F. 1977 Effects of the initial condition on the axisym-metric free shear layer: effect of the initial fluctuation level. Phys. Fluids 21 (in press).Google Scholar
Karamcheti, K., Bauer, A. E., Shields, W. L., Stegen, G. R. & Woolley, J. P. 1969 N.A.S.A. Special Paper no. 207, p. 275.
Kline, S. J., Coles, D. E., Eggers, J. M. & Harsha, P. T. 1973 N.A.S.A. Special Paper no. 321, p. 655.
Ko, N. W. M. & Davies, P. O. A. L. 1971 J. Fluid Mech. 50, 49.
Ko, N. W. M. & Kwan, A. S. H. 1976 J. Fluid Mech. 73, 305.
Kovasznay, L. S. G. 1949 Proc. Roy. Soc. A 198, 174.
Kovasznay, L. S. G. 1977 Large scale structures in turbulence – a question or an answer? Symp. Turbulence, Berlin.
Lamb, H. 1945 Hydrodynamics. Dover.
Liepmann, H. & Laufer, J. 1947 N.A.C.A. Tech. Note no. 1257.
Lin, C. C. 1955 The Hydrodynamic Stability Theory. Cambridge University Press.
Ling, C. & Reynolds, W. C. 1973 J. Fluid Mech. 59, 571.
Liu, J. T. C. 1974 J. Fluid Mech. 62, 437.
Mccanless, G. F. & Boone, J. R. 1974 J. Acoust. Soc. Am. 56, 1501.
Michalke, A. 1965 J. Fluid Mech. 23, 521.
Michalke, A. 1972 Prog. Aero. Sci. 12, 213.
Moore, D. W. & Saffman, P. G. 1975 J. Fluid Mech. 69, 465.
Naudascher, E. 1967 Proc. A.S.C.E. 93(HY4), 15.
Nyborg, W. L. 1954 J. Acoust. Soc. Am. 26, 2.
Powell, A. 1961 J. Acoust. Soc. Am. 33, 4.
Richardson, E. G. 1931 Proc. Phys. Soc. 43, 394.
Roshko, A. 1976 A.I.A.A. J. 10, 1349.
Sarohia, V. 1977 A.I.A.A. J. 15, 984.
Sato, H. 1960 J. Fluid Mech. 7, 53.
Winant, C. D. & Browand, F. K. 1974 J. Fluid Mech. 63, 237.
Woolley, J. P. & Karamcheti, J. 1974 A.I.A.A. J. 12, 1457.
Zaman, K. B. M. Q. & Hussain, A. K. M. F. 1977 Proc. Symp. Turbulent Shear Flow, Penn. State Univ., pp. 11.23–11.31.