Hostname: page-component-848d4c4894-x5gtn Total loading time: 0 Render date: 2024-05-29T23:18:16.468Z Has data issue: false hasContentIssue false
  • English
  • Français

Noise reduction mechanisms for insert-type serrations of the NACA-0012 airfoil

Published online by Cambridge University Press:  09 May 2022

Ya-Sen Hu Open the ORCID record for Ya-Sen Hu [Opens in a new window] ,
Zhen-Hua Wan Open the ORCID record for Zhen-Hua Wan [Opens in a new window] ,
Chuang-Chao Ye ,
De-Jun Sun  and
Xi-Yun Lu Open the ORCID record for Xi-Yun Lu [Opens in a new window]
Ya-Sen Hu
Affiliation:
Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, PR China
Zhen-Hua Wan*
Affiliation:
Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, PR China
Chuang-Chao Ye
Affiliation:
Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, PR China
De-Jun Sun
Affiliation:
Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, PR China
Xi-Yun Lu
Affiliation:
Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, PR China
*
†Email address for correspondence: wanzh@ustc.edu.cn
Get access Rights & Permissions [Opens in a new window]

Abstract

Trailing-edge serrations inspired by owls are capable of reducing broadband noise. In this study, the wall-resolved large-eddy simulations (LES) are carried out on the flow over NACA-0012 airfoil with additional serrated trailing edges. The computations are conducted with the high-order flux reconstruction method on unstructured meshes. Three kinds of serrations with different lengths are studied and compared with the straight trailing-edge case, and all three types of serration achieved a certain degree of noise reduction. Presently, the medium-length serration achieves the best noise reduction effect. The maximum decrease of overall sound pressure level is approximately 2.4 dB, implying that the length of serration has a substantial impact on the noise reduction effect. The serration has no significant effect on the upstream turbulence statistics, but it changes the flow structure near the serration, such as inducing side vortex pairs attached to the serration edges. Moreover, dynamic mode decomposition shows that the pressure structures vary with the serration length. For the most unstable hydrodynamic wave, the spanwise coherence of the mode structure of pressure in the upstream boundary layer is weakened. In addition, serrations can redistribute the dipole sources on the surfaces of airfoil and serrations. The destructive interference is enhanced to some extent, which is favourable for noise reduction. In contrast with LES simulations, the pure dipole analysis shows that the longest serration case seems to be the best. Furthermore, a recently developed noise theory is used to evaluate the influence of serrations on the flow noise sources qualitatively and quantitatively. It is found that the serrations can mitigate noise source intensity near the serration edges but increase the source intensity in the near wake. The combined effect of serration on the dipole source and flow noise source determines the overall noise reduction effect. To conclude, destructive interference plays a primary role in suppressing noise radiation by serrated trailing edges, and the dual effect of flow noise sources should be considered in future serration designs. As the influence of turbulence structure will make it more difficult to find the optimal serration parameters, the position of high-fidelity simulation will become increasingly important.

JFM classification

Acoustics: Aeroacoustics Turbulent Flows: Turbulent boundary layers Aerodynamics: Flow-structure interactions
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 941 , 25 June 2022 , A57
Check for updates
Copyright
© The Author(s), 2022. 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

Amiet, R.K. 1976 Noise due to turbulent flow past a trailing edge. J. Sound Vib. 47 (3), 387–393.CrossRefGoogle Scholar
Avallone, F., Pröbsting, S. & Ragni, D. 2016 Three-dimensional flow field over a trailing-edge serration and implications on broadband noise. Phys. Fluids 28 (11), 117101.CrossRefGoogle Scholar
Avallone, F., van der Velden, W.C.P. & Ragni, D. 2017 Benefits of curved serrations on broadband trailing-edge noise reduction. J. Sound Vib. 400, 167–177.CrossRefGoogle 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
Ayton, L.J. 2018 Analytic solution for aerodynamic noise generated by plates with spanwise-varying trailing edges. J. Fluid Mech. 849, 448–466.CrossRefGoogle Scholar
Azarpeyvand, M., Gruber, M. & Joseph, P. 2013 An analytical investigation of trailing edge noise reduction using novel serrations. In 19th AIAA/CEAS Aeroacoustics Conference, Berlin, Germany, AIAA Paper 2013–2009.Google Scholar
Braun, K.A., Van der Borg, N.J.C.M., Dassen, A.G.M., Gordner, A. & Parchen, R. 1997 Noise reduction by using serrated trailing edges. In European Wind Energy Conference, Dublin, Germany, pp. 472–475.Google Scholar
Brentner, K.S. & Farassat, F. 1998 Analytical comparison of the acoustic analogy and kirchhoff formulation for moving surfaces. AIAA J. 36 (8), 1379–1386.CrossRefGoogle Scholar
Brooks, T.F., Pope, D. & Marcolini, M. 1989 Airfoil self-noise and prediction. NASA Tech. Rep. 1218.Google Scholar
Chong, T.P., Joseph, P., Vathylakis, A. & Gruber, M. 2011 On the noise and wake flow of an airfoil with broken and serrated trailing edges. In 17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), Portland, OR, USA, AIAA Paper 2011–2860.Google Scholar
Chong, T.P. & Vathylakis, A. 2015 On the aeroacoustic and flow structures developed on a flat plate with a serrated sawtooth trailing edge. J. Sound Vib. 354, 65–90.CrossRefGoogle 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 European Union Wind Energy Conference and Exhibition, Gothenburg, Sweden, pp. 800–803.Google Scholar
Ffowcs Williams, J.E. & Hawkings, D.L. 1969 Sound generation by turbulence and surfaces in arbitrary motion. Phil. Trans. R. Soc. Lond. Ser. A 264 (1151), 321–342.Google Scholar
Finez, A., Jacob, M., Roger, M. & Jondeau, E. 2011 Broadband noise reduction of linear cascades with trailing edge serrations. In 17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), Portland, OR, USA, AIAA Paper 2011-2874.Google Scholar
Gelot, M.B. & Kim, J.W. 2020 Effect of serrated trailing edges on aerofoil tonal noise. J. Fluid Mech. 904, A30.CrossRefGoogle Scholar
Graham, R.R. 1934 The silent flight of owls. J. R. Aero. Soc. 38 (286), 837–843.CrossRefGoogle Scholar
Griffin, K.P., Fu, L. & Moin, P. 2021 General method for determining the boundary layer thickness in nonequilibrium flows. Phys. Rev. Fluids 6 (2), 024608.CrossRefGoogle Scholar
Gruber, M. 2012 Airfoil noise reduction by edge treatments. PhD thesis, University of Southampton.Google Scholar
Gruber, M., Azarpeyvand, M. & Joseph, P.F. 2010 a Airfoil trailing edge noise reduction by the introduction of sawtooth and slitted trailing edge geometries. In Proceedings of the 20th International Congress on Acoustics, ICA 10, Sydney, Australia, p. 1–9.Google Scholar
Gruber, M., Joseph, P. & Chong, T.P. 2010 b Experimental investigation of airfoil self noise and turbulent wake reduction by the use of trailing edge serrations. In 16th AIAA/CEAS Aeroacoustics Conference, Stockholm, Sweden, AIAA Paper 2010-3803.Google Scholar
Gruber, M., Joseph, P. & Chong, T. 2011 On the mechanisms of serrated airfoil trailing edge noise reduction. In 17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), Portland, OR, USA, AIAA Paper 2011-2781.Google Scholar
Herr, M. & Reichenberger, J. 2011 In search of airworthy trailing-edge noise reduction means. In 17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), Portland, OR, USA, AIAA Paper 2011-2780.Google Scholar
Howe, M.S. 1978 A review of the theory of trailing edge noise. J. Sound Vib. 61 (3), 437–465.CrossRefGoogle Scholar
Howe, M.S. 1991 Noise produced by a sawtooth trailing edge. J. Acoust. Soc. Am. 90 (1), 482–487.CrossRefGoogle Scholar
Huang, X. 2017 Theoretical model of acoustic scattering from a flat plate with serrations. J. Fluid Mech. 819, 228–257.CrossRefGoogle Scholar
Huynh, H.T. 2007 A flux reconstruction approach to high-order schemes including discontinuous Galerkin methods. In 18th AIAA Computational Fluid Dynamics Conference, Miami, FL, USA, AIAA Paper 2007-4079.Google Scholar
Jaworski, J.W. & Peake, N. 2020 Aeroacoustics of silent owl flight. Annu. Rev. Fluid Mech. 52, 395–420.CrossRefGoogle Scholar
Ji, L., Qiao, W., Tong, F., Xu, K. & Chen, W. 2014 Experimental and numerical study on noise reduction mechanisms of the airfoil with serrated trailing edge. In 20th AIAA/CEAS Aeroacoustics Conference, Atlanta, GA, USA, AIAA Paper 2014-3297.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
Kholodov, P. & Moreau, S. 2020 Numerical study of optimized airfoil trailing-edge serrations for broadband noise reduction. In 26th AIAA/CEAS Aeroacoustics Conference, Virtual Event, AIAA Paper 2020-2541.Google Scholar
Kim, J. 1989 On the structure of pressure fluctuations in simulated turbulent channel flow. J. Fluid Mech. 205, 421–451.CrossRefGoogle Scholar
Lee, H & Kang, S.H. 2000 Flow characteristics of transitional boundary layers on an airfoil in wakes. J. Fluids Eng. 122 (3), 522–532.CrossRefGoogle Scholar
León, C.A., Avallone, F., Pröbsting, S. & Ragni, D. 2016 a PIV investigation of the flow past solid and slitted sawtooth serrated trailing edges. In 54th AIAA Aerospace Sciences Meeting, California, USA, AIAA Paper 2016-1014.Google Scholar
León, C.A., Merino-Martínez, R., Ragni, D., Avallone, F. & Snellen, M. 2016 b Boundary layer characterization and acoustic measurements of flow-aligned trailing edge serrations. Exp. Fluids 57 (12), 182.CrossRefGoogle Scholar
León, C.A., Ragni, D., Pröbsting, S., Scarano, F. & Madsen, J. 2016 c Flow topology and acoustic emissions of trailing edge serrations at incidence. Exp. Fluids 57 (5), 91.CrossRefGoogle Scholar
Lighthill, M.J. 1952 On sound generated aerodynamically I. General theory. Proc. R. Soc. Lond. A 211 (1107), 564–587.Google Scholar
Liu, X., Azarpeyvand, M. & Theunissen, R. 2015 Aerodynamic and aeroacoustic performance of serrated airfoils. In 21st AIAA/CEAS Aeroacoustics Conference, Dallas, TX, USA, AIAA Paper 2015-2201.Google Scholar
Lyu, B., Azarpeyvand, M. & Sinayoko, S. 2016 Prediction of noise from serrated trailing edges. J. Fluid Mech. 793, 556–588.CrossRefGoogle Scholar
Mao, F., Kang, L.L., Wu, J.Z., Yu, J.L., Gao, A.K., Su, W.D. & Lu, X.Y. 2020 A study of longitudinal processes and interactions in compressible viscous flows. J. Fluid Mech. 893, A23.CrossRefGoogle Scholar
Marsden, O., Bogey, C. & Bailly, C. 2006 Direct noise computation around a 3-D NACA 0012 airfoil. In 12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference), Cambridge, MA, USA, AIAA Paper 2006-2503.Google Scholar
Moreau, D., Brooks, L. & Doolan, C. 2012 On the noise reduction mechanism of a flat plate serrated trailing edge at low-to-moderate Reynolds number. In 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference), Colorado Springs, CO, USA, AIAA Paper 2012-2186.Google Scholar
Moreau, D. & Doolan, C.J. 2013 Tonal noise from trailing edge serrations at low Reynolds number. In 19th AIAA/CEAS Aeroacoustics Conference, Berlin, Germany, AIAA Paper 2013-2010.Google Scholar
Moreau, S., Sanjosé, M., Lyu, B. & Ayton, L.J. 2019 Analytical, numerical and experimental investigation of trailing-edge noise reduction on a controlled diffusion airfoil with serrations. In 25th AIAA/CEAS Aeroacoustics Conference, Delft, Netherland, AIAA Paper 2019-2450.Google Scholar
Najafi-Yazdi, A., Brès, G.A. & Mongeau, L. 2011 An acoustic analogy formulation for moving sources in uniformly moving media. Proc. R. Soc. Lond. A 467 (2125), 144–165.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
Park, J.S., Witherden, F.D. & Vincent, P.E. 2017 High-order implicit large-eddy simulations of flow over a NACA0021 aerofoil. AIAA J. 55 (7), 2186–2197.CrossRefGoogle Scholar
Qiao, W., Ji, L., Tong, F., Chen, W. & Xu, K. 2014 Experimental and numerical study on noise reduction mechanisms of the linear cascade with serrated trailing edge. In 20th AIAA/CEAS Aeroacoustics Conference, Atlanta, GA, USA, AIAA Paper 2014-3349.Google Scholar
Ribeiro, A.F., Casalino, D., Fares, E. & Choudhari, M. 2016 Direct numerical simulation of an airfoil with sand grain roughness on the leading edge. NASA/TM–2016-219363.Google Scholar
Sandberg, R.D. & Jones, L.E. 2011 Direct numerical simulations of low reynolds number flow over airfoils with trailing-edge serrations. J. Sound Vib. 330 (16), 3818–3831.CrossRefGoogle Scholar
Sanjosé, M., Méon, C., Moreau, S., Idier, A. & Laffay, P. 2014 Direct numerical simulation of acoustic reduction using serrated trailing-edge on an isolated airfoil. In 20th AIAA/CEAS Aeroacoustics Conference, Atlanta, GA, USA, AIAA Paper 2014-2324.Google Scholar
Schmid, P.J. 2010 Dynamic mode decomposition of numerical and experimental data. J. Fluid Mech. 656, 5–28.CrossRefGoogle Scholar
Schmid, P.J., Li, L., Juniper, M.P. & Pust, O. 2011 Applications of the dynamic mode decomposition. Theor. Comput. Fluid Dyn. 25 (1), 249–259.CrossRefGoogle Scholar
Teruna, C., Avallone, F., Ragni, D. & Casalino, D. 2021 On the noise reduction of a porous trailing edge applied to an airfoil at lifting condition. Phys. Fluids 33 (5), 055132.CrossRefGoogle Scholar
Teruna, C., Manegar, F., Avallone, F., Ragni, D., Casalino, D. & Carolus, T. 2020 Noise reduction mechanisms of an open-cell metal-foam trailing edge. J. Fluid Mech. 898, A18.CrossRefGoogle Scholar
Tong, F., Qiao, W.Y., Ji, L., Xu, K.B. & Wang, X.N. 2016 Experimental study on the turbomachinery trailing edge noise reduction. In Turbo Expo: Power for Land, Sea, and Air, Seoul, South Korea, vol. 49699, p. V02AT41A002. American Society of Mechanical Engineers.CrossRefGoogle Scholar
van der Velden, W.C.P. & Oerlemans, S. 2017 Numerical analysis of noise reduction mechanisms on improved trailing edge serrations using the lattice Boltzmann method. In 35th Wind Energy Symposium, Grapevine, TX, USA, AIAA Paper 2017-1379.Google Scholar
Witherden, F.D., Farrington, A.M. & Vincent, P.E. 2014 PyFR: an open source framework for solving advection–diffusion type problems on streaming architectures using the flux reconstruction approach. Comput. Phys. Commun. 185 (11), 3028–3040.CrossRefGoogle Scholar
Wolf, W.R., Azevedo, J.L.F. & Lele, S.K. 2012 Convective effects and the role of quadrupole sources for aerofoil aeroacoustics. J. Fluid Mech. 708, 502–538.CrossRefGoogle Scholar
Yang, Y., Wang, Y., Liu, Y., Hu, H. & Li, Z. 2020 Noise reduction and aerodynamics of isolated multi-copter rotors with serrated trailing edges during forward flight. J. Sound Vib. 489, 115688.CrossRefGoogle Scholar