Hostname: page-component-78c5997874-ndw9j Total loading time: 0 Render date: 2024-11-09T01:54:57.470Z Has data issue: false hasContentIssue false
  • English
  • Français

Effect of serrated trailing edges on aerofoil tonal noise

Published online by Cambridge University Press:  13 October 2020

Matthieu B. R. Gelot Open the ORCID record for Matthieu B. R. Gelot [Opens in a new window]  and
Jae Wook Kim Open the ORCID record for Jae Wook Kim [Opens in a new window]
Matthieu B. R. Gelot*
Affiliation:
Institute of Sound and Vibration Research, University of Southampton, Highfield, SouthamptonSO17 1BJ, UK
Jae Wook Kim
Affiliation:
Institute of Sound and Vibration Research, University of Southampton, Highfield, SouthamptonSO17 1BJ, UK
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

A wall-resolved large-eddy simulation of a symmetric Joukowski aerofoil with a 12 % thickness at a Reynolds number of 250 000, a Mach number of 0.4 and zero incidence angle is performed in order to investigate the effect of using a serrated trailing edge on the acoustic feedback event that generates a tonal noise. The acoustic feedback is investigated in detail to emphasise the interaction between the upstream travelling acoustic expansion wave and the laminar separation bubble. The simulation shows that the serrated trailing edges may result in a significant reduction of the tonal noise. This paper provides detailed investigations into the noise reduction mechanisms. The main finding is that the presence of a serrated trailing edge decreases the amplitude of the acoustic source pressure in the transitional region and gives rise to destructive phase interference in the wall pressure fluctuations in the vicinity of the trailing edge which weakens the acoustic feedback loop.

JFM classification

Acoustics: Aeroacoustics Turbulent Flows: Turbulence simulation
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 904 , 10 December 2020 , A30
Check for updates
Copyright
© The Author(s), 2020. Published by 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

REFERENCES

Arbey, H. & Bataille, J. 1983 Noise generated by airfoil profiles placed in a uniform laminar flow. J. Fluid Mech. 134, 33–47.CrossRefGoogle Scholar
Arcondoulis, E. J. G., Doolan, C. J., Zander, A. C. & Brooks, L. A. 2013 An experimental investigation of airfoil tonal noise caused by an acoustic feedback loop. In Annual Conference of the Australian Acoustical Society 2013, pp. 23–30. Australian Acoustical Society.Google Scholar
Avallone, F., van der Velden, W. C. P., Ragni, D. & Casalino, D. 2018 Noise reduction mechanisms of sawtooth and combed-sawtooth trailing-edge serrations. J. Fluid Mech. 848, 560–591.CrossRefGoogle Scholar
Brooks, T. F., Pope, D. S. & Marcolini, M. A. 1989 Airfoil self-noise and prediction. Tech. Rep. NASA-RP-1218. National Aeronautics and Space Administration.Google Scholar
Chong, T. P. & Joseph, P. F. 2013 An experimental study of airfoil instability tonal noise with trailing edge serrations. J. Sound Vib. 332 (24), 6335–6358.CrossRefGoogle Scholar
Chong, T. P., Joseph, P. F. & Kingan, M. J. 2013 An investigation of airfoil tonal noise at different Reynolds numbers and angles of attack. Appl. Acoust. 74, 38–48.CrossRefGoogle Scholar
Desquesnes, G., Terracol, M. & Sagaut, P. 2007 Numerical investigation of the tone noise mechanism over laminar airfoils. J. Fluid Mech. 591, 155–182.CrossRefGoogle Scholar
Farassat, F. 2007 Derivation of formulations 1 and 1A of Farassat. Tech. Rep. National Aeronautics and Space Administration.Google Scholar
Fink, M. R. 1975 Prediction of airfoil tone frequencies. J. Aircraft 12 (2), 118–120.CrossRefGoogle Scholar
Garmann, D. J., Visbal, M. R. & Orkwis, P. D. 2013 Comparative study of implicit and subgrid-scale model large-eddy simulation techniques for low-Reynolds number airfoil applications. Intl J. Numer. Meth. Fluids 71 (12), 1546–1565.CrossRefGoogle Scholar
Georgiadis, N. J., Rizzetta, D. P. & Fureby, C. 2010 Large-Eddy simulation: current capabilities, recommended practices, and future research. AIAA J. 48 (8), 1772–1784.CrossRefGoogle Scholar
Goldstein, M. E. 1976 Aeroacoustics. McGraw-Hill.Google Scholar
Gruber, M., Joseph, P. F. & Chong, T. P. 2011 On the mechanisms of serrated airfoil trailing edge noise reduction. In 17th AIAA/CEAS Aeroacoustics Conference, pp. 1–23. AIAA.Google Scholar
Jones, L. E. & Sandberg, R. D. 2011 Numerical analysis of tonal airfoil self-noise and acoustic feedback-loops. J. Sound Vib. 330 (25), 6137–6152.CrossRefGoogle Scholar
Kim, J. W. 2007 Optimised boundary compact finite difference schemes for computational aeroacoustics. J. Comput. Phys. 225, 995–1019.CrossRefGoogle Scholar
Kim, J. W. 2010 High-order compact filters with variable cut-off wavenumber and stable boundary treatment. Comput. Fluids 39, 1168–1182.CrossRefGoogle Scholar
Kim, J. W. 2013 Quasi-disjoint pentadiagonal matrix systems for the parallelization of compact finite-difference schemes and filters. J. Comput. Phys. 241, 168–194.CrossRefGoogle Scholar
Kim, J. W., Lau, A. S. H. & Sandham, N. D. 2010 a CAA boundary conditions for airfoil noise due to high-frequency gusts. Procedia Engng 6, 244–253.CrossRefGoogle Scholar
Kim, J. W., Lau, A. S. H. & Sandham, N. D. 2010 b Proposed boundary conditions for gust-airfoil interaction noise. AIAA J. 48 (11), 2705–2710.CrossRefGoogle Scholar
Kim, J. W. & Lee, D. J. 2000 Generalized characteristic boundary conditions for computational aeroacoustics. AIAA J. 38 (11), 2040–2049.CrossRefGoogle Scholar
Longhouse, R. E. 1977 Vortex shedding noise of low tip speed, axial flow fans. J. Sound Vib. 53 (1), 25–46.CrossRefGoogle Scholar
McAlpine, A., Nash, E. C. & Lowson, M. V. 1999 On the generation of discrete frequency tones by the flow around an aerofoil. J. Sound Vib. 222 (5), 753–779.CrossRefGoogle Scholar
Nash, E. C., Lowson, M. V. & McAlpine, A. 1999 Boundary-layer instability noise on aerofoils. J. Fluid Mech. 382, 27–61.CrossRefGoogle Scholar
Nguyen, L. D., Golubev, V. V., Mankbadi, R. R., Yakhina, G., Roger, M., Pasiliao, C. L. & Visbal, M. R. 2017 On ladder-type structure of acoustic tones radiated by transitional airfoils. In 23rd AIAA/CEAS Aeroacoustics Conference, pp. 1–14. AIAA.Google Scholar
Padois, T., Laffay, P., Idier, A. & Moreau, S. 2016 Tonal noise of a controlled-diffusion airfoil at low angle of attack and Reynolds number. J. Acoust. Soc. Am. 140 (1), 113–118.CrossRefGoogle ScholarPubMed
Paterson, R. W., Vogt, P. G., Fink, M. R. & Munch, C. L. 1973 Vortex noise of isolated airfoils. J. Aircraft 10 (5), 296–302.CrossRefGoogle Scholar
Pröbsting, S., Scarano, F. & Morris, S. C. 2015 Regimes of tonal noise on an airfoil at moderate Reynolds number. J. Fluid Mech. 780, 407–438.CrossRefGoogle Scholar
Pröbsting, S., Serpieri, J. & Scarano, F. 2014 Experimental investigation of aerofoil tonal noise generation. J. Fluid Mech. 747 (2), 656–687.CrossRefGoogle Scholar
Sanjose, M., Jaiswal, P., Moreau, S., Towne, A., Lele, S. K. & Mann, A. 2017 Laminar boundary layer instability noise. In 23rd AIAA/CEAS Aeroacoustics Conference, pp. 1–13. AIAA.Google Scholar
Tam, C. K. W. 1974 Discrete tones of isolated airfoils. J. Acoust. Soc. Am. 55 (6), 1173–1177.CrossRefGoogle Scholar
Tam, C. K. W. & Ju, H. 2012 Aerofoil tones at moderate Reynolds number. J. Fluid Mech. 690, 536–570.CrossRefGoogle Scholar
Turner, J. M. & Kim, J. W. 2019 On the universal trends in the noise reduction due to wavy leading edges in aerofoil-vortex interaction. J. Fluid Mech. 871, 186–211.CrossRefGoogle Scholar
Turner, J. M. & Kim, J. W. 2020 Effect of spanwise domain size on direct numerical simulations of airfoil noise during flow separation and stall. Phys. Fluids 32 (6), 1–15.CrossRefGoogle Scholar
White, F. M. 1991 Viscous Fluid Flows. McGraw-Hill.Google Scholar