Hostname: page-component-745bb68f8f-b95js Total loading time: 0 Render date: 2025-01-09T07:18:00.980Z Has data issue: false hasContentIssue false
  • English
  • Français

Acoustic and hydrodynamic analysis of the flow around an aerofoil with trailing-edge serrations

Published online by Cambridge University Press:  06 July 2012

L. E. Jones  and
R. D. Sandberg
L. E. Jones*
Affiliation:
Aerodynamics and Flight Mechanics Research Group, School of Engineering Sciences, University of Southampton, Southampton SO17 1BJ, UK
R. D. Sandberg
Affiliation:
Aerodynamics and Flight Mechanics Research Group, School of Engineering Sciences, University of Southampton, Southampton SO17 1BJ, UK
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Direct numerical simulations of the flow around a NACA-0012 aerofoil are conducted, employing an immersed boundary method to represent flat-plate trailing-edge extensions both with and without serrations. Properties of the turbulent boundary layer convecting over the trailing edge are similar for both cases. For cases with serrations, the trailing-edge noise produced by the flow over the aerofoil is observed to decrease in amplitude, and the frequency interval over which the noise reduction occurs differs depending on the serration length. The directivity and spanwise coherence of the trailing-edge noise appears largely unaffected by the serrations. The hydrodynamic behaviour in the vicinity of the trailing-edge extensions is investigated. The streamwise discontinuity imparted upon the turbulent flow by the straight trailing edge can clearly be observed in statistical quantities, whereas for the serrated case no spanwise homogeneous discontinuities are observed. The trailing-edge serrations appear to break up the larger turbulent structures convecting into the wake, and to promote the development of horseshoe vortices originating at the serrations themselves.

JFM classification

Acoustics: Aeroacoustics Acoustics: Noise control Turbulent Flows: Turbulent boundary layers
Type
Papers
Information
Journal of Fluid Mechanics , Volume 706 , 10 September 2012 , pp. 295 - 322
Copyright
Copyright © Cambridge University Press 2012

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

1. Amiet, R. K. 1976 Noise due to turbulent flow past a trailing edge. J. Sound Vib. 47 (3), 387–393.CrossRefGoogle Scholar
2. Brooks, T. F., Pope, D. S. & Marcolini, M. A. 1989 Airfoil Self-Noise and Prediction. NASA Reference Publication 1218, NASA.Google Scholar
3. Callender, B., Gutmark, E. & Martens, S. 2005 Far-field acoustic investigation into chevron nozzle mechanisms and trends. AIAA J. 43 (1), 87–95.CrossRefGoogle Scholar
4. Carpenter, M. H., Nordström, J. & Gottlieb, D. 1999 A stable and conservative interface treatment of arbitrary spatial accuracy. J. Comput. Phys. 148 (2), 341–365.CrossRefGoogle Scholar
5. 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.CrossRefGoogle Scholar
6. Gruber, M. & Joseph, P. F. 2011 On the mechanisms of serrated aerofoil trailing edge noise reduction. In 17th AIAA/CEAS Aeroacoustics Conference, Portland, Oregon, June. AIAA.CrossRefGoogle Scholar
7. Head, M. R. & Bandyopadhyay, P. 1981 New aspects of turbulent boundary-layer structure. J. Fluid Mech. 107, 297–338.CrossRefGoogle Scholar
8. Herr, M. & Dobrzynski, W. 2005 Experimental investigations in low-noise trailing-edge design. AIAA J. 43 (6), 1167–1175.CrossRefGoogle Scholar
9. Howe, M. S. 1991 Noise produced by a sawtooth trailing edge. J. Acoust. Soc. Am. 90, 482.CrossRefGoogle Scholar
10. Jones, L. E. 2007 Numerical studies of the flow around an aerofoil at low Reynolds number. PhD thesis, University of Southampton.Google Scholar
11. Jones, L. E., Sandberg, R. S. & Sandham, N. D. 2008 Direct numerical simulations of forced and unforced separation bubbles on an aerofoil at incidence. J. Fluid Mech. 602, 175–207.CrossRefGoogle Scholar
12. Jones, L. E., Sandberg, R. D. & Sandham, N. D. 2009 Investigation and prediction of transitional airfoil self-noise. In AIAA Paper 2009–3104, 15th AIAA/CEAS Aeroacoustics Conference, Miami, May. AIAA.CrossRefGoogle Scholar
13. Jones, L. E., Sandberg, R. S. & Sandham, N. D. 2010a Stability and receptivity characteristics of a laminar separation bubble on an aerofoil. J. Fluid Mech. 648, 257–296.CrossRefGoogle Scholar
14. Jones, L. E., Sandham, N. D. & Sandberg, R. D. 2010b Acoustic source identification for transitional aerofoil flows using cross correlations. AIAA J. 48 (10), 2299–2312.CrossRefGoogle Scholar
15. Lighthill, M. J. 1952 On sound generated aerodynamically. Part 1. General theory. Proc. R. Soc. Lond. Ser. A: Math. Phys. Sci. 211A (1107), 564–587.Google Scholar
16. Mittal, R. & Iaccarino, G. 2005 Immersed boundary methods. Annu. Rev. Fluid Mech. 37, 239–261.CrossRefGoogle Scholar
17. Oerlemans, S., Fisher, M., Maeder, T. & Kögler, K. 2009 Reduction of wind turbine noise using optimized aerofoils and trailing-edge serrations. AIAA J. 47 (6), 1470–1481.CrossRefGoogle Scholar
18. Sandberg, R. D. & Jones, L. E. 2011 Direct numerical simulations of low Reynolds number flow over aerofoils with trailing-edge serrations. J. Sound Vib. 330, 3818–3831.CrossRefGoogle Scholar
19. Sandberg, R. D., Jones, L. E. & Sandham, N. D. 2008 Direct numerical simulations of noise generated by turbulent flow over aerofoils. AIAA Paper 2008–2861, 14th AIAA/CEAS Aeroacoustics Conference, Vancouver, Canada. AIAA.CrossRefGoogle Scholar
20. Sandberg, R. D. & Sandham, N. D. 2006 Nonreflecting zonal characteristic boundary condition for direct numerical simulation of aerodynamic sound. AIAA J. 44 (2), 402–405.CrossRefGoogle Scholar
21. Sandham, N. D., Li, Q. & Yee, H. C. 2002 Entropy splitting for high-order numerical simulation of compressible turbulence. J. Comput. Phys. 178, 307–322.CrossRefGoogle Scholar
22. White, F. M. 1991 Viscous Fluid Flow. McGraw-Hill.Google Scholar