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Pressure fluctuations produced by forward steps immersed in a turbulent boundary layer

Published online by Cambridge University Press:  02 September 2014

Manuj Awasthi ,
William J. Devenport ,
Stewart A. L. Glegg  and
Jonathan B. Forest
Manuj Awasthi
Affiliation:
Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
William J. Devenport*
Affiliation:
Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
Stewart A. L. Glegg
Affiliation:
Department of Ocean and Mechanical Engineering, Florida Atlantic University, Boca Raton, FL 33431, USA
Jonathan B. Forest
Affiliation:
Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
*
†Email address for correspondence: [email protected]
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Abstract

Experiments have been performed on the disturbance of a high-Reynolds-number turbulent boundary layer by three forward steps with sizes close to 3.8, 15 and 60 % of the boundary layer thickness. Particular attention is focused on the impact of the steps on the fluctuating surface pressure field. Measurements were made from 5 boundary layer thicknesses upstream to 22 boundary layer thicknesses downstream of the step, a distance equivalent to over 600 step heights for the smallest step size. Flow speeds of 30 and $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}60\ \mathrm{m}\ {\mathrm{s}}^{-1}$ were studied, corresponding to boundary layer momentum thickness Reynolds numbers of 15 500 and 26 600 and step size Reynolds numbers from 6640 to 213 000. The steps produce a disturbance to the boundary layer pressure spectrum that scales on step size and decays remarkably slowly with distance downstream. When normalized on step height and free-stream velocity, the disturbance is self-similar and appears to develop almost independently of the enveloping boundary layer. The disturbance is still clearly visible at 150 step heights downstream of the mid-size step. Pressure correlations show the disturbance to be characterized by organized quasiperiodic motions that become visible well downstream of reattachment. The coherence and scale of these motions, as seen in the wall pressure correlations, scales on the step height and thus their visibility relative to the boundary layer grows rapidly as the step size is increased.

JFM classification

Boundary Layers: Boundary layer separation Boundary Layers: Boundary layer structure Turbulent Flows: Turbulent Flows
Type
Papers
Information
Journal of Fluid Mechanics , Volume 756 , 10 October 2014 , pp. 384 - 421
Copyright
© 2014 Cambridge University Press 

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References

Awasthi, M.2012 High Reynolds number turbulent boundary layer flow over small forward facing steps. MS thesis, Virginia Polytechnic Institute and State University. http://scholar.lib.vt.edu/theses/available/etd-06292012-120614/.Google Scholar
Batchelor, G. K. 1953 The Theory of Homogeneous Turbulence. Cambridge University Press.Google Scholar
Bearman, P. W. 1971 Corrections for the effect of ambient temperature drift on hot-wire measurements in incompressible flow. DISA Inform. 11, 25–30.Google Scholar
Blake, W. 1970 Turbulent boundary layer wall-pressure fluctuations on smooth and rough walls. J. Fluid Mech. 44, 637–660.CrossRefGoogle Scholar
Bradshaw, P. 1967 Inactive motion and pressure fluctuations in turbulent boundary layers. J. Fluid Mech. 30, 241–258.CrossRefGoogle Scholar
Camussi, R., Felli, M., Pereira, F., Aloisio, G. & Di Marco, A. 2008 Statistical properties of wall pressure fluctuations over a forward-facing step. Phys. Fluids 20 (7), 075113.CrossRefGoogle Scholar
Camussi, R., Guj, G. & Ragni, A. 2006 Wall pressure fluctuations induced by turbulent boundary layers over surface discontinuities. J. Sound Vib. 294 (1–2), 177–204.CrossRefGoogle Scholar
Castro, I. P. & Epik, E. 1998 Boundary layer development after a separated region. J. Fluid Mech. 374, 91–116.CrossRefGoogle Scholar
Cherry, N. J., Hillier, R. & Latour, M. E. M. P. 1984 Unsteady measurements in a separated and reattaching flow. J. Fluid Mech. 144, 13–46.CrossRefGoogle Scholar
Devenport, W. J., Burdisso, R. A., Borgoltz, A., Ravetta, P. A., Barone, M. F., Brown, K. A. & Morton, M. A. 2013 The Kevlar-walled anechoic wind tunnel. J. Sound Vib. 332 (17), 3971–3991.CrossRefGoogle Scholar
Devenport, W. J., Grissom, D. L., Alexander, W. N., Smith, B. S. & Glegg, S. A. L. 2011 Measurements of roughness noise. J. Sound Vib. 330, 4250–4273.CrossRefGoogle Scholar
Eaton, J. K. & Johnston, J. P. 1981 A review of research on subsonic turbulent flow reattachment. AIAA J. 19 (9), 1093–1100.CrossRefGoogle Scholar
Efimstov, B. M., Golubev, A. Y., Rizzi, S. A., Andersson, A. O., Rackl, R. G. & Andrianov, E. V.2002 Influence of small steps on wall pressure fluctuation spectral measured on a TU144LL flying laboratory. AIAA Paper 2002-2605.CrossRefGoogle Scholar
Efimtsov, B. M., Kozlov, N. M., Kravchenko, S. V. & Andersson, A. O.1999 Wall pressure fluctuation spectra at small forward facing steps. AIAA Paper 99-1964.CrossRefGoogle Scholar
Farabee, T. M. & Casarella, M. J. 1986 Measurements of fluctuating wall pressure for separated/reattached boundary layer flows. ASME J. Vib. Acoust. Stress Reliab. Des. 108, 301–307.CrossRefGoogle Scholar
Fiorentini, E., Felli, M., Pereira, F., Camussi, R. & Di Marco, A.2007 Wall pressure fluctuations over a forward-facing step. AIAA Paper 2007-8411.CrossRefGoogle Scholar
George, W. K., Beuther, P. D. & Arndt, R. E. A. 1984 Pressure spectra in turbulent free shear flows. J. Fluid Mech. 148, 155–191.CrossRefGoogle Scholar
Goody, M. 2004 Empirical spectral model of surface pressure fluctuations. AIAA J. 42 (9), 1788–1794.CrossRefGoogle Scholar
Hillier, R. & Cherry, N. J. 1981 The effects of stream turbulence on separation bubbles. J. Wind Engng Ind. Aerodyn. 8 (1–2), 49–58.CrossRefGoogle Scholar
Horne, P.1990 Physical and computational investigation of the wall pressure fluctuations in a channel flow. NRL Memorandum Report 6628, Naval Research Laboratory.Google Scholar
Ji, M. & Wang, M. 2010 Sound generation by turbulent boundary layer flow over small steps. J. Fluid Mech. 654, 161–193.CrossRefGoogle Scholar
Ji, M. & Wang, M. 2012 Surface pressure fluctuations on steps immersed in turbulent boundary layers. J. Fluid Mech. 712, 471–504.CrossRefGoogle Scholar
Kiya, M. & Sasaki, K. 1983 Structure of a turbulent separation bubble. J. Fluid Mech. 137, 83–113.CrossRefGoogle Scholar
Kiya, M. & Sasaki, K. 1985 Structure of large-scale vortices and unsteady reverse flow in the reattaching zone of a turbulent separation bubble. J. Fluid Mech. 154, 463–491.CrossRefGoogle Scholar
Largeau, J. F. & Moriniere, V. 2007 Wall pressure fluctuations and topology in separated flows over a forward-facing step. Exp. Fluids 42 (1), 21–40.CrossRefGoogle Scholar
Leclercq, D. J. J., Jacob, M. C., Louisot, A. & Talotte, C.2001 Forward–backward facing step pair: aerodynamic flow, wall pressure and acoustic characterization. AIAA Paper 2001-2249.Google Scholar
Lee, L. & Sung, H. J. 2001 Characteristics of wall pressure fluctuations in separated and reattaching flows over a backward-facing step: part 1. Time-mean statistics and cross-spectral analyses. Exp. Fluids 30, 262–272.CrossRefGoogle Scholar
Lee, I. & Sung, H. J. 2002 Multiple-arrayed pressure measurement for investigation of the unsteady flow structure of a reattaching shear layer. J. Fluid Mech. 463, 377–402.CrossRefGoogle Scholar
McGrath, B. E. & Simpson, R. L.1987 Some features of surface pressure fluctuations in turbulent boundary layers with zero and favorable pressure gradients. NASA CR-4051.Google Scholar
Panton, R. & Linebarger, J. 1974 Wall pressure spectra calculations for equilibrium boundary layers. J. Fluid Mech. 65 (2), 261–287.CrossRefGoogle Scholar
Sherry, M. J., Jocono, D. L., Sheridan, J., Mathis, R. & Marusic, I. 2009 Flow separation characterization of a forward facing step immersed in a turbulent boundary layer. In Sixth Symposium on Turbulence and Shear Flow Phenomena, Seoul, South Korea, 22–24 June.Google Scholar
Steinwolf, A. & Rizzi, S. A. 2006 Non-Gaussian analysis of turbulent boundary layer fluctuating pressure on aircraft skin panels. J. Aircraft 43 (6), 1662–1675.CrossRefGoogle Scholar
Tachie, M. F., Balachandar, R. & Bergstrom, D. J. 2001 Open channel boundary layer relaxation behind a forward facing step at low Reynolds numbers. Trans. ASME J. Fluids Engng 123 (3), 539–544.CrossRefGoogle Scholar
Wittmer, K. S., Devenport, W. J. & Zsoldos, J. S. 1998 A four sensor hot wire probe system for three component velocity measurements. Exp. Fluids 24, 416–423; see also 27(4), U1.CrossRefGoogle Scholar