Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-19T22:41:17.206Z Has data issue: false hasContentIssue false
  • English
  • Français

Prediction of noise from serrated trailing edges

Published online by Cambridge University Press:  18 March 2016

B. Lyu ,
M. Azarpeyvand  and
S. Sinayoko
B. Lyu
Affiliation:
Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
M. Azarpeyvand*
Affiliation:
Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, UK
S. Sinayoko
Affiliation:
Institute of Sound and Vibration Research, University of Southampton, Southampton SO17 1BJ, UK
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

A new analytical model is developed for the prediction of noise from serrated trailing edges. The model generalizes Amiet’s trailing-edge noise theory to sawtooth trailing edges, resulting in a complicated partial differential equation. The equation is then solved by means of a Fourier expansion technique combined with an iterative procedure. The solution is validated through comparison with the finite element method for a variety of serrations at different Mach numbers. The results obtained using the new model predict noise reduction of up to 10 dB at 90$^{\circ }$ above the trailing edge, which is more realistic than predictions based on Howe’s model and also more consistent with experimental observations. A thorough analytical and numerical analysis of the physical mechanism is carried out and suggests that the noise reduction due to serration originates primarily from interference effects near the trailing edge. A closer inspection of the proposed mathematical model has led to the development of two criteria for the effectiveness of the trailing-edge serrations, consistent but more general than those proposed by Howe. While experimental investigations often focus on noise reduction at 90$^{\circ }$ above the trailing edge, the new analytical model shows that the destructive interference scattering effects due to the serrations cause significant noise reduction at large polar angles, near the leading edge. It has also been observed that serrations can significantly change the directivity characteristics of the aerofoil at high frequencies and even lead to noise increase at high Mach numbers.

JFM classification

Acoustics: Aeroacoustics Acoustics: Noise control Turbulent Flows: Turbulent boundary layers
Type
Papers
Information
Journal of Fluid Mechanics , Volume 793 , 25 April 2016 , pp. 556 - 588
Check for updates
Copyright
© 2016 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

Amiet, R. K. 1975 Acoustic radiation from an airfoil in a turbulent stream. J. Sound Vib. 41 (4), 407–420.CrossRefGoogle Scholar
Amiet, R. K. 1976a High frequency thin-airfoil theory for subsonic flow. AIAA J. 14 (8), 1076–1082.Google Scholar
Amiet, R. K. 1976b Noise due to turbulent flow past a trailing edge. J. Sound Vib. 47 (3), 387–393.Google Scholar
Amiet, R. K. 1978 Effect of the incident surface pressure field on noise due to turbulent flow past a trailing edge. J. Sound Vib. 57, 305–306.Google Scholar
Azarpeyvand, M., Gruber, M. & Joseph, P. F. 2013 An analytical investigation of trailing edge noise reduction using novel serrations. In Proceedings of 19th AIAA/CEAS Aeroacoustics Conference. Berlin, Germany.Google Scholar
Callender, B., Gutmark, E. J. & Martens, S. 2005 Far-field acoustic investigation into chevron nozzle mechanisms and trends. AIAA J. 43 (1), 87–95.Google Scholar
Casalino, D., Diozzi, F., Sannino, R. & Paonessa, A. 2008 Aircraft noise reduction technologies: a bibliographic review. Aerosp. Sci. Technol. 12, 1–17.Google Scholar
Chase, D. M. 1975 Noise radiated from an edge in turbulent flow. AIAA J. 13, 1041–1047.Google Scholar
Chase, D. M. 1987 The character of the turbulent wall pressure spectrum at subconvective wavenumbers and a suggested comprehensive model. J. Sound Vib. 112, 125–147.Google Scholar
Corcos, G. M. 1964 The structure of the turbulent pressure field in boundary-layer flows. J. Fluid Mech. 18, 353–378.Google Scholar
Curle, N. 1955 The influence of solid boundaries upon aerodynamic sound. Proc. R. Soc. Lond. A 231, 505–514.Google Scholar
Dassen, A. G. M., 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 Proceedings of European Union Wind Energy Conference and Exhibition, pp. 800–803.Google Scholar
Eckert, E. R. & Drake, R. M. 1959 Heat and Mass Transfer. McGraw-Hill.Google Scholar
Gruber, M.2012 Airfoil noise reduction by edge treatments. PhD thesis, University of Southampton, Southampton, UK.Google Scholar
Gruber, M., Joseph, P. F. & Azarpeyvand, M. 2013 An experimental investigation of novel trailing edge geometries on airfoil trailing edge noise reduction. In Proceedings of 19th AIAA/CEAS Aeroacoustics Conference, Berlin, Germany.Google Scholar
Howe, M. S. 1991a Aerodynamic noise of a serrated trailing edge. J. Fluids Struct. 5, 33–45.Google Scholar
Howe, M. S. 1991b Noise produced by a sawtooth trailing edge. J. Acoust. Soc. Am. 90, 482–487.Google Scholar
Jones, L. E. & Sandberg, R. D. 2012 Acoustic and hydrodynamic analysis of the flow around an aerofoil with trailing-edge serrations. J. Fluid Mech. 706, 295–322.CrossRefGoogle Scholar
Lamb, H. 1932 Hydrodynamics, 6th edn. Dover.Google Scholar
Lighthill, M. J. 1952 On sound generated aerodynamically. I. General theory. Proc. R. Soc. Lond. A 211, 564–587.Google Scholar
Moreau, D. J. & Doolan, C. J. 2013 Noise-reduction mechanism of a flat-plate serrated trailing edge. AIAA J. 51, 2513–2522.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, 1470–1481.CrossRefGoogle Scholar
Oerlemans, S., Sijtsma, P. & Méndez López, B 2007 Location and quantification of noise sources on a wind turbine. J. Sound Vib. 299 (4C5), 869–883.CrossRefGoogle Scholar
Parchen, R., Hoffmans, W., Gordner, A. & Braun, K. 1999 Reduction of airfoil self-noise at low Mach number with a serrated trailing edge. In International Congress on Sound and Vibration, 6th Technical University of Denmark, Lyngby, Denmark, pp. 3433–3440.Google Scholar
Roger, M. & Carazo, A. 2010 Blade-geometry considerations in analytical gust–airfoil interaction noise models. In Proceedings of 16th AIAA/CEAS Aeroacoustic Conference, Stockholm, Sweden.Google Scholar
Roger, M. & Moreau, S. 2005 Back-scattering correction and further extensions of Amiet’s trailing-edge noise model. Part 1: theory. J. Sound Vib. 286, 477–506.Google Scholar
Roger, M., Schram, C. & Santana, L. D. 2013 Reduction of airfoil turbulence-impingement noise by means of leading-edge serrations and/or porous materials. In Proceedings of 19th AIAA/CEAS Aeroacoustics Conference, Berlin, Germany, pp. 1–20.Google Scholar
Süli, E. & Mayers, D. 2003 An Introduction to Numerical Analysis. Cambridge University Press.Google Scholar
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, 657–670.Google Scholar
Willmarth, W. W.1959 Space–time correlations and spectra of wall pressure in a turbulent boundary layer. NASA Tech Memo 3-17-59W.Google Scholar
Yan, J., Panek, L. & Thiele, F. 2007 Simulation of jet noise from a long-cowl nozzle with serrations. In Proceedings of 13th AIAA/CEAS Aeroacoustics Conference, Rome, Italy.Google Scholar