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The forced turbulent wall jet

Published online by Cambridge University Press:  26 April 2006

Y. Katz ,
E. Horev  and
I. Wygnanski
Y. Katz
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
E. Horev
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
I. Wygnanski
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
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Abstract

The effects of external two-dimensional excitation on the plane turbulent wall jet were investigated experimentally and theoretically. Measurements of the streamwise component of velocity were made throughout the flow field for a variety of imposed frequencies and amplitudes. The present data were always compared to the results generated in the absence of external excitation. Two methods of forcing were used: one global, imposed on the entire jet by pressure fluctuations in the settling chamber and one local, imposed on the shear layer by a small flap attached to the outer nozzle lip. The fully developed wall jet was shown to be insensitive to the method of excitation. Furthermore, external excitation has no appreciable effect on the rate of spread of the jet nor on the decay of its maximum velocity. In fact the mean velocity distribution did not appear to be altered by the external excitation in any obvious manner. The flow near the surface, however, (i.e. for 0 < Y+ < 100) was profoundly different from the unforced flow, indicating a reduction in wall stress exceeding at times 30%. The production of turbulent energy near the surface was also reduced, lowering the intensities of the velocity fluctuations. External excitation enhanced the two-dimensionality and the periodicity of the coherent motion. Spectral analysis and flow visualization suggested that the large coherent structures in this flow might be identified with the most-amplified primary instability modes of the mean velocity profile. Detailed stability analysis confirmed this proposition though not at the same level of accuracy as it did in many free shear flows.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 242 , September 1992 , pp. 577 - 609
Copyright
© 1992 Cambridge University Press

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References

Cohen, J. & Wygnanski, I. 1987 The evolution of instabilities in the axisymmetric jet. Part 1. The linear growth of disturbances near the nozzle. J. Fluid Mech. 176, 191.Google Scholar
Craik, A. D. D. 1985 Wave Interactions and Fluid Flows. Cambridge University Press.
Crighton, D. G. & Gaster, M. 1976 Stability of slowly diverging jet flow. J. Flow Mech. 77, 397.Google Scholar
Falco, R. E. 1977 Coherent motion in the outer region of turbulent boundary layers. Phys. Fluids Suppl. 20, 124.Google Scholar
Gaster, M. 1974 On the effects of boundary layer growth on flow stability. J. Fluid Mech. 66, 465.Google Scholar
Gaster, M., Kit, E. & Wygnanski, I. 1985 Large scale structures in a forced turbulent mixing layer. J. Fluid Mech. 150, 23.Google Scholar
Glauert, M. B. 1956 The wall-jet. J. Fluid Mech. 1, 625.Google Scholar
Ho, C. M. & Huerre, P. 1984 Perturbed free shear layers. Ann. Rev. Fluid Mech. 16, 365.Google Scholar
Hussain, A. K. M. F. & Reynolds, W. C. 1970 The mechanics of an organized wave in turbulent shear flow. J. Fluid Mech. 41, 241.Google Scholar
Hussain, A. K. M. F. & Reynolds, W. C. 1972 The mechanics of an organized wave in turbulent shear flow. Part 2. Experimental results. J. Fluid Mech. 54, 241.Google Scholar
Katz, Y., Nishri, B. & Wygnanski, I. 1989 The delay of turbulent boundary-layer separation by oscillatory active control. AIAA Paper 89-0975.Google Scholar
Kline, S. J., Reynolds, W. C., Schraub, F. A. & Runstadler, P. W. 1967 The structure of turbulent boundary layers. J. Fluid Mech. 50, 133.Google Scholar
Kruka, V. & Eskinazi, S. 1964 The wall-jet in a moving stream. J. Fluid Mech. 20, 555.Google Scholar
Landahl, M. T. 1990 On sublayer streaks. J. Fluid Mech. 212, 593.Google Scholar
Launder, B. E. & Rodi, W. 1981 The turbulent wall jets. Prog. Aerospace Sci. 19, 81.Google Scholar
Launder, B. E. & Rodi, W. 1983 The turbulent wall jet — measurements and modeling. Ann. Rev. Fluid Mech. 15, 429.Google Scholar
Liu, J. T. C. 1971 Nonlinear development of instability wave in a turbulent wake. Phys. Fluids 14, 2251.Google Scholar
Marasli, B., Champagne, F. H. & Wygnanski, I. J. 1989 Model decomposition of velocity signals in a plane, turbulent wake. J. Fluid Mech. 198, 255.Google Scholar
Narasimha, R., Narayan, K. Y. & Parthasarathy, S. P. 1973 Parametric analysis of turbulent wall jets in still air. Aeronaut. J. 77, 335.Google Scholar
Tam, C. K. W. & Chen, K. C. 1979 A statistical model of turbulence in two-dimensional mixing layers. J. Fluid Mech. 92, 303.Google Scholar
Tsuji, Y., Morikawa, Y., Nagatani, T. & Sakou, M. 1977 The stability of a two-dimensional wall-jet. Aeronaut. Q. XXVIII (November), 235.Google Scholar
Weisbrot, I. & Wygnanski, I. 1988 On coherent structures in a highly excited mixing layer. J. Fluid Mech. 195, 137.Google Scholar
Willmarth, W. W. 1975a Pressure fluctuations beneath turbulent boundary layers. Ann. Rev. Fluid Mech. 7, 13.Google Scholar
Willmarth, W. W. 1975b Structure of turbulence in boundary layers. Advances in Applied Mechanics, vol. 15 (ed. C.-S. Yih), p. 159. Academic.
Wills, J. A. B. 1962 The correction of hot-wire readings for proximity to a solid boundary. J. Fluid Mech. 12, 3.Google Scholar
Wygnanski, I., Champagne, F. & Marasli, B. 1986 On the large scale structures in two-dimensional, small-deficit, turbulent wakes. J. Fluid Mech. 168, 31.Google Scholar
Wygnanski, I., Fiedler, H., Oster, D. & Dziomba, B. 1979 On the perseverance of a quasi-two-dimensional eddy structure in a turbulent mixing layer. J. Fluid Mech. 93, 325.Google Scholar
Wygnanski, I., Katz, Y. & Horev, E. 1992 On the applicability of various scaling laws to the turbulent wall jet. J. Fluid Mech. 234, 669 (referred to herein as WKH).Google Scholar
Wygnanski, I. & Petersen, R. A. 1987 Coherent motion in excited free shear layers. AIAA J. 25, 201.Google Scholar