Hostname: page-component-54dcc4c588-9xpg2 Total loading time: 0 Render date: 2025-09-20T16:33:10.737Z Has data issue: false hasContentIssue false
  • English
  • Français

Trailing-edge flow manipulation using streamwise finlets

Published online by Cambridge University Press:  14 May 2019

Abbas Afshari Open the ORCID record for Abbas Afshari [Opens in a new window] ,
Mahdi Azarpeyvand ,
Ali A. Dehghan ,
Máté Szőke  and
Reza Maryami
Abbas Afshari
Affiliation:
Yazd University, Yazd, Iran
Mahdi Azarpeyvand*
Affiliation:
Department of Mechanical Engineering, University of Bristol, BristolBS8 1TR, UK
Ali A. Dehghan
Affiliation:
Yazd University, Yazd, Iran
Máté Szőke
Affiliation:
Department of Mechanical Engineering, University of Bristol, BristolBS8 1TR, UK
Reza Maryami
Affiliation:
Yazd University, Yazd, Iran
*
†Email address for correspondence: m.azarpeyvand@bristol.ac.uk
Get access Rights & Permissions [Opens in a new window]

Abstract

The use of streamwise finlets as a passive flow and aerodynamic noise-control technique is considered in this paper. A comprehensive experimental investigation is undertaken using a long flat plate, and results are presented for the boundary layer and surface pressure measurements for a variety of surface treatments. The pressure–velocity coherence results are also presented to gain a better understanding of the effects of the finlets on the boundary layer structures. The results show that the flow behaviour downstream of the finlets is strongly dependent on the finlet spacing. The use of finlets with coarse spacing leads to a reduction in pressure spectrum at mid- to high frequencies and an increase in spanwise length scale in the trailing-edge region due to flow channelling effects. For the finely distributed finlets, the flow is observed to behave similarly to that of a permeable backward-facing step, with significant suppression of the high-frequency pressure fluctuations but an elevation at low frequencies. Furthermore, the convection velocity is observed to reduce downstream of all finlet treatments. The trailing-edge surface pressure spectrum results have shown that, in order to obtain maximum unsteady pressure reduction, the finlet spacing should be of the order of the thickness of the inner layer of the boundary layer. A thorough study is provided for understanding of the underlying physics of both categories of finlets and their implications for controlling the flow and noise generation mechanism near the trailing edge.

JFM classification

Acoustics: Aeroacoustics Boundary Layers: Boundary layer control Turbulent Flows: Turbulent boundary layers

Information

Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 870 , 10 July 2019 , pp. 617 - 650
Copyright
© 2019 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.)

Article purchase

Temporarily unavailable

Footnotes

A preliminary version of this paper was presented as Paper 2016-2834 at the 22nd AIAA/CEAS Aeroacoustics Conference, Lyon, France, 30 May–1 June 2016.

References

Afshari, A., Azarpeyvand, M., Dehghan, A. A. & Szoke, M. 2017 Effects of streamwise surface treatments on trailing edge noise reduction. In 23rd AIAA/CEAS Aeroacoustics Conference, p. 3499.Google Scholar
Ai, Q., Azarpeyvand, M., Lachenal, X. & Weaver, P. M. 2016 Aerodynamic and aeroacoustic performance of airfoils with morphing structures. Wind Energy 19 (7), 1325–1339.Google Scholar
Ali, S. A., Azarpeyvand, M., Szőke, M. & Ilário da Silva, C. R. 2018a Boundary layer flow interaction with a permeable wall. Phys. Fluids 30 (8), 085111.Google Scholar
Ali, S. A. S., Azarpeyvand, M. & Ilário da Silva, C. R. 2018b Trailing-edge flow and noise control using porous treatments. J. Fluid Mech. 850, 83–119.Google Scholar
Amiet, R. K. 1976 Noise due to turbulent flow past a trailing edge. J. Sound Vib. 47 (3), 387–393.Google Scholar
Badran, O. O. & Bruun, H. H. 1999 Comparison of flying-hot-wire and stationary-hot-wire measurements of flow over a backward-facing step. Trans. ASME J. Fluids Engng 121 (2), 441–445.Google Scholar
Bechert, D., Bruse, M., Hage, W., Van der Hoeven, J. & Hoppe, G. 1997 Experiments on drag-reducing surfaces and their optimization with an adjustable geometry. J. Fluid Mech. 338, 59–87.Google Scholar
Bendat, J. S. & Piersol, A. G. 2011 Random Data: Analysis and Measurement Procedures. Wiley.Google Scholar
Blake, W. K. 1970 Turbulent boundary-layer wall-pressure fluctuations on smooth and rough walls. J. Fluid Mech. 44 (4), 637–660.Google Scholar
Blake, W. 2017 Mechanics of Flow-Induced Sound and Vibration, Volume 2: Complex Flow–Structure Interactions, 2nd edn. Academic.Google Scholar
Bradshaw, P. & Wong, F. 1972 The reattachment and relaxation of a turbulent shear layer. J. Fluid Mech. 52 (1), 113–135.Google Scholar
Brooks, T. F. & Hodgson, T. H. 1981 Trailing edge noise prediction from measured surface pressures. J. Sound Vib. 78, 69–117.Google Scholar
Brooks, T. F., Pope, D. S. & Marcolini, M. A.1989 Airfoil self-noise and prediction. NASA Technical Report.Google Scholar
Bruun, H. H. 1995 Hot-Wire Anemometry: Principles and Signal Analysis. Oxford University Press.Google Scholar
Cassiani, M., Katul, G. & Albertson, J. 2008 The effects of canopy leaf area index on airflow across forest edges: large-eddy simulation and analytical results. Boundary-Layer Meteorol. 126 (3), 433–460.Google Scholar
Cherry, N., Hillier, R. & Latour, M. 1984 Unsteady measurements in a separated and reattaching flow. J. Fluid Mech. 144, 13–46.Google Scholar
Clark, I., Alexander, N., Devenport, W., Glegg, S., Jaworski, J., Daily, C. & Peake, N. 2017 Bio-inspired trailing edge noise control. AIAA J. 55 (3), 740–754.Google Scholar
Clark, I., Daly, C., Devenport, W., Alexander, N., Peake, N., Jaworski, J. & Glegg, S. 2016 Bio-inspired canopies for the reduction of roughness noise. J. Sound Vib. 385, 33–54.Google Scholar
Coles, D. 1956 The law of the wake in the turbulent boundary layer. J. Fluid Mech. 1 (2), 191–226.Google Scholar
Coles, D.1969 Turbulent boundary layers in pressure gradients: a survey lecture prepared for the 1968 AFOSR-IFP-Stanford Conference on Computation of Turbulent Boundary Layers. Tech. Rep. Rand Corp. Santa Monica, CA, USA.Google Scholar
Corcos, G. 1963 Resolution of pressure in turbulence. J. Acoust. Soc. Am. 35 (2), 192–199.Google Scholar
Corcos, G. 1964 The structure of the turbulent pressure field in boundary-layer flows. J. Fluid Mech. 18 (3), 353–378.Google Scholar
Dassen, T., Parchen, R., Bruggeman, J. & Hagg, F. 1996 Results of a wind tunnel study on the reduction of airfoil self-noise by the application of serrated blade trailing edges. In Proc. of the European Union Wind Energy Conference and Exhibition, Göteborg, Sweden.Google Scholar
Dean, B. & Bhushan, B. 2010 Shark-skin surfaces for fluid-drag reduction in turbulent flow: a review. Phil. Trans. R. Soc. Lond. A 368 (1929), 4775–4806.Google Scholar
Durbin, P. A. & Reif, P. 2011 Statistical Theory and Modeling for Turbulent Flows. Wiley.Google Scholar
Eaton, J. K. & Johnston, J. P. 1981 A review of research on subsonic turbulent flow reattachment. AIAA J. 19 (9), 1093–1100.Google Scholar
Farabee, T. M. & Casarella, M. J. 1986 Measurements of fluctuating wall pressure for separated/reattached boundary layer flows. J. Vib. Acoust. 108 (3), 301–307.Google Scholar
Ffowcs Williams, J. E. & Hall, L. H. 1970 Aerodynamic sound generation by turbulent flow in the vicinity of a scattering half plane. J. Fluid Mech. 40 (4), 657–670.Google Scholar
Finez, A., Jondeau, E., Roger, M. & Jacob, M.2010 Broadband noise reduction with trailing edge brushes. In 16th AIAA/CEAS Aeroacoustics Conference, AIAA 2010-3980.Google Scholar
Finnigan, J. 2000 Turbulence in plant canopies. Annu. Rev. Fluid Mech. 32 (1), 519–571.Google Scholar
Freymuth, P. 1967 Feedback control theory for constant-temperature hot-wire anemometers. Rev. Sci. Instrum. 38 (5), 677–681.Google Scholar
Garcia-Sagrado, A. & Hynes, T. 2011 Wall-pressure sources near an airfoil trailing edge under separated laminar boundary layers. AIAA J. 49 (9), 1841–1856.Google Scholar
Garcia-Sagrado, A. & Hynes, T. 2012 Wall pressure sources near an airfoil trailing edge under turbulent boundary layers. J. Fluids Struct. 30, 3–34.Google Scholar
Geyer, T., Sarradj, E. & Fritzsche, C. 2010 Measurement of the noise generation at the trailing edge of porous airfoils. Exp. Fluids 48 (2), 291–308.Google Scholar
Goody, M. 2004 Empirical spectral model of surface pressure fluctuations. AIAA J. 42 (9), 1788–1794.Google Scholar
Goody, M. C. & Simpson, R. L. 2000 Surface pressure fluctuations beneath two- and three-dimensional turbulent boundary layers. AIAA J. 38 (10), 1822–1831.Google Scholar
Gravante, S. P., Naguib, A. M., Wark, C. E. & Nagib, H. M. 1998 Characterization of the pressure fluctuations under a fully developed turbulent boundary layer. AIAA J. 36 (10), 1808–1816.Google Scholar
Gruber, M.2012 Airfoil noise reduction by edge treatments. PhD thesis, University of Southampton.Google Scholar
Herr, M. & Dobrzynski, W. 2005 Experimental investigations in low-noise trailing-edge design. AIAA J. 43 (6), 1167–1175.Google Scholar
Howe, M. 1978 A review of the theory of trailing edge noise. J. Sound Vib. 61 (3), 437–465.Google Scholar
Howe, M. 1979 On the added mass of a perforated shell, with application to the generation of aerodynamic sound by a perforated trailing edge. Proc. R. Soc. Lond. A 365 (1721), 209–233.Google Scholar
Howe, M. 1991 Noise produced by a sawtooth trailing edge. J. Acoust. Soc. Am. 90 (1), 482–487.Google Scholar
Hu, N. & Herr, M.2016 Characteristics of wall pressure fluctuations for a flat plate turbulent boundary layer with pressure gradients. In 22nd AIAA/CEAS Aeroacoustics Conference, AIAA 2016-2749.Google Scholar
Hwang, Y. F., Bonness, W. K. & Hambric, S. A. 2009 Comparison of semi-empirical models for turbulent boundary layer wall pressure spectra. J. Sound Vib. 319 (1–2), 199–217.Google Scholar
Jawahar, H. K., Ai, Q. & Azarpeyvand, M. 2018 Experimental and numerical investigation of aerodynamic performance for airfoils with morphed trailing edges. Renew. Energy 127, 355–367.Google Scholar
Ji, M. & Wang, M. 2012 Surface pressure fluctuations on steps immersed in turbulent boundary layers. J. Fluid Mech. 712, 471–504.Google Scholar
Jones, B., Crossley, W. & Lyrintzis, A. 2000 Aerodynamic and aeroacoustic optimization of rotorcraft airfoils via a parallel genetic algorithm. J. Aircraft 37 (6), 1088–1096.Google Scholar
Kendall, A. & Koochesfahani, M.2006 A method for estimating wall friction in turbulent boundary layers. In 25th AIAA Aerodynamic Measurement Technology and Ground Testing Conference, AIAA 2006-3834.Google Scholar
Kiya, M. & Sasaki, K. 1983 Structure of a turbulent separation bubble. J. Fluid Mech. 137, 83–113.Google Scholar
Lee, S. J. & Lee, S. H. 2001 Flow field analysis of a turbulent boundary layer over a riblet surface. Exp. Fluids 30 (2), 153–166.Google Scholar
Lee, I. & Sung, H. J. 2001 Characteristics of wall pressure fluctuations in separated and reattaching flows over a backward-facing step: Part I. Time-mean statistics and cross-spectral analyses. Exp. Fluids 30 (3), 262–272.Google 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.Google Scholar
Liu, X., Kamliya Jawahar, H., Azarpeyvand, M. & Theunissen, R. 2017 Aerodynamic performance and wake development of airfoils with serrated trailing-edges. AIAA J. 3669–3680.Google Scholar
Liu, Y. Z., Kang, W. & Sung, H. J. 2005 Assessment of the organization of a turbulent separated and reattaching flow by measuring wall pressure fluctuations. Exp. Fluids 38 (4), 485–493.Google Scholar
Liu, Y. Z., Ke, F., Chen, H. P. & Sung, H. J. 2006 A wall-bounded turbulent mixing layer flow over an open step: I. Time-mean and spectral characteristics. J. Turbul. 7 (65), N65.Google Scholar
Lyu, B., Azarpeyvand, M. & Sinayoko, S. 2016 Prediction of noise from serrated trailing edges. J. Fluid Mech. 793, 556–588.Google Scholar
Markfort, C. D., Porté-Agel, F. & Stefan, H. G. 2014 Canopy-wake dynamics and wind sheltering effects on earth surface fluxes. Environ. Fluid Mech. 14 (3), 663–697.Google Scholar
Marusic, I., Chauhan, K. A., Kulandaivelu, V. & Hutchins, N. 2015 Evolution of zero-pressure-gradient boundary layers from different tripping conditions. J. Fluid Mech. 783, 379–411.Google Scholar
Maryami, R., Azarpeyvand, M., Dehghan, A. A. & Afshari, A. 2019 An experimental investigation of the surface pressure fluctuations for round cylinders. Trans. ASME J. Fluids Engng 141 (6), 061203.Google 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 Tech. Rep. CR-4051.Google Scholar
Mish, P. F.2001 Mean loading and turbulence scale effects on the surface pressure fluctuations occurring on a NACA 0015 airfoil immersed in grid generated turbulence. MSc thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.Google Scholar
Mosallem, M. 2008 Numerical and experimental investigation of beveled trailing edge flow fields. J. Hydrodyn. B 20 (3), 273–279.Google Scholar
Naka, Y., Stanislas, M., Foucaut, J.-M., Coudert, S., Laval, J.-P. & Obi, S. 2015 Space–time pressure–velocity correlations in a turbulent boundary layer. J. Fluid Mech. 771, 624–675.Google Scholar
Oerlemans, S., Fisher, M., Maeder, T. & Kögler, K. 2009 Reduction of wind turbine noise using optimized airfoils and trailing-edge serrations. AIAA J. 47 (6), 1470–1481.Google Scholar
Plate, E. 1971 The aerodynamics of shelter belts. Agric. Meteorol. 8, 203–222.Google Scholar
Pope, S. B. 2001 Turbulent Flows. IOP Publishing.Google Scholar
Raine, J. & Stevenson, D. 1977 Wind protection by model fences in a simulated atmospheric boundary layer. J. Wind Engng Ind. Aerodyn. 2 (2), 159–180.Google Scholar
Roger, M. & Moreau, S. 2004 Broadband self noise from loaded fan blades. AIAA J. 42 (3), 536–544.Google Scholar
Roos, F. W. & Kegelman, J. T. 1986 Control of coherent structures in reattaching laminar and turbulent shear layers. AIAA J. 24 (12), 1956–1963.Google Scholar
Schewe, G. 1983 On the structure and resolution of wall-pressure fluctuations associated with turbulent boundary-layer flow. J. Fluid Mech. 134, 311–328.Google Scholar
Schlatter, P. & Örlü, R. 2012 Turbulent boundary layers at moderate Reynolds numbers: inflow length and tripping effects. J. Fluid Mech. 710, 5–34.Google Scholar
Spalding, D. 1961 A single formula for the law of the wall. J. Appl. Mech. 28 (3), 455–458.Google Scholar
Troutt, T. R., Scheelke, B. & Norman, T. R. 1984 Organized structures in a reattaching separated flow field. J. Fluid Mech. 143, 413–427.Google Scholar
Willmarth, W. & Roos, F. 1965 Resolution and structure of the wall pressure field beneath a turbulent boundary layer. J. Fluid Mech. 22 (1), 81–94.Google Scholar
Winant, C. D. & Browand, F. K. 1974 Vortex pairing: the mechanism of turbulent mixing-layer growth at moderate Reynolds number. J. Fluid Mech. 63 (12), 237–255.Google Scholar
Yavuzkurt, S. 1984 A guide to uncertainty analysis of hot-wire data. Trans. ASME J. Fluids Engng 106 (2), 181–186.Google Scholar