A large-eddy simulation is carried out on a rod-airfoil configuration and compared to an accompanying experiment as well as to a RANS computation. A NACA0012 airfoil (chord c = 0.1 m) is located one chord downstream of a circular rod (diameter d = c/10, Red = 48 000). The computed interaction of the resulting sub-critical vortex street with the airfoil is assessed using averaged quantities, aerodynamic spectra and proper orthogonal decomposition (POD) of the instantaneous flow fields. Snapshots of the flow field are compared to particle image velocimetry (PIV) data. The acoustic far field is predicted using the Ffowcs Williams & Hawkings acoustic analogy, and compared to the experimental far field spectra. The large-eddy simulation is shown to accurately represent the deterministic pattern of the vortex shedding that is described by POD modes 1 & 2 and the resulting tonal noise also compares favourably to measurements. Furthermore higher order POD modes that are found in the PIV data are well predicted by the computation. The broadband content of the aerodynamic and the acoustic fields is consequently well predicted over a large range of frequencies ([0 kHz; 10 kHz]).
Get full access to this article
View all access options for this article.
References
1.
StrouhalV., Über eine besondere Art der Tonerregung, Annalen der Physik und Chemie, 1878, 3(5), 216–251.
2.
WagnerH., Über die Entstehung des dynamischen Auftriebes von tragflügeln, Zeitschrift fur Angewandte Mathematik und Mechanik, 1925, 5(1-2), 17–35.
3.
GlauertH., The force and moment on an oscillating airfoil, British Aeronautical Research Council, Reports & Memoranda, No. 1242, 1929.
4.
KüssnerH.G., Zusammenfassender Bericht über den instationären Auftrieb von Flügeln, Luftfahrtforschung, 1936, 13, 410–424.
5.
SearsW.R., Some aspects of non-stationary airfoil theory and its practical application, Journal of Aeronautical Sciences, 1941, 8 (3), 104–108.
6.
GrahamJ.W.S., Similarity rules for thin airfoils in non-stationary subsonic flows, Journal of Fluid mechanics, 1970, 43(4), 753–766.
7.
WidnallS., Helicopter noise due to blade-vortex interaction, Journal of the Acoustical Society of America, 1971, 51(3), 354–365.
8.
AmietR.K., High frequency thin airfoil theory for subsonic flow, American Institute of Aeronautics and Astronautics Journal, 1976, 14(8), 1076–1082.
9.
AmietR.K., Low frequency approximations in unsteady small perturbation of subsonic flows, Journal of Fluid Mechanics, 1975, 75(3), 545–552.
10.
GoldsteinM.E.AtassiH.M., A complete second order theory for the unsteady flow about an airfoil due to a periodic gust, Journal of Fluid Mechanics, 1976, 74(1-2), 741–765.
11.
TerracolM.ManohaE.HerreroC.SagautP., Airfoil noise prediction using large-eddy simulation, Euler equations and Kirchhoff integral, LES for Acoustics, Göttingen, 2002.
12.
HansonD.B., Spectrum of rotor noise caused by atmospheric turbulence, Journal of the Acoustical Society of America, 1974, 56 (1-2), 110–126.
13.
HomiczG.F.GeorgeA.R., Broadband and discrete frequency radiation from subsonic rotors, Journal of Sound and Vibration, 1974, 36 (2), 151–177.
14.
MajumdarS.J.PeakeN., Noise generation by the interaction between ingested turbulence and a rotating fan, Journal of Fluid Mechanics, 1998, 359, 181–216.
15.
GleggS., The response of a swept blade row to a 3D gust, Journal of Sound and Vibration, 1999, 227(1-2), 29–64.
16.
BoudetJ., Approches numériques pour la simulation du bruit à large bande en vue de l'application aux turbomachines, PhD. Thesis, No. d'ordre: 2003–36, Ecole Centrale de Lyon, 2003.
17.
BoudetJ.CasalinoD.JacobM.C.FerrandP., Unsteady RANS computations of the flow past an airfoil in the wake of a rod, American Society of Mechanical Engineers FEDSM 2002, paper No. FEDSM2002–31343, Montreal, 2002.
18.
BaillyC.LafonP.CandelS., A stochastic approach to compute noise generation and radiation of free turbulent flows, American Institute of Aeronautics and Astronautics, paper 95–092, 1995.
19.
SerorC.SagautP.BaillyC.JuveD., On the Radiated Noise computed by Large-Eddy Simulation, Physics of Fluids, 2001, 13(2), 476–487.
20.
Ffowcs-WilliamsJ.E.HawkingsD.L., Sound Generated by Turbulence and Surfaces in Arbitrary Motion, Philosophical Transactions of the Royal Society, 1969, A264 (1151), 321–342.
21.
SchönwaldN.LiS.D.SchemelC.EschrichD.BoltalovaN.ThieleF., Numerical simulation of sound propagation and radiation from aero-engines, ERCOFTAC Bulletin, 2003, 58, 55–58.
22.
JacobM.C.BoudetJ.CasalinoD.MichardM., A rod-airfoil experiment as benchmark for broadband noise modelling, to appear in Theoretical and Computational Fluid Dynamics (published online by Springer Verlag), 2004.
23.
SmatiL.AubertS.FerrandP.MassaoF., Comparison of numerical schemes to investigate blade flutter, 8th International Symposium on Unsteady Aerodynamics and Aeroelasticity of Turbomachines, Stockholm, 1997.
24.
ErlebacherG.HussainiM.Y.SpezialeC.G.ZangT.A., Towards the large-eddy simulation of compressible turbulent flows, Journal of Fluid Mechanics, 1992, 238, 155–185.
25.
BoudetJ.CasalinoD.JacobM.J.FerrandP., Prediction of sound radiated by a rod using large-eddy simulation, American Institute of Aeronautics and Astronautics, AIAA paper 2003–3217, Hilton Head, 2003 (also submitted to AIAA Journal).
26.
SmagorinskyJ., Numerical study of small-scale intermittency in three-dimensional turbulence, Monthly Weather Review, 1963, 91, 99–164.
27.
van DriestE.R., On the turbulent flow near a wall, Journal of Aeronautical Sciences, 1956, 23, 1007–1011.
28.
WilcoxD.C., Comparison of two-equation turbulence models for boundary layers with pressure gradient, American Institute of Aeronautics and Astronautics Journal, 1993, 31(8), 1414–1421.
29.
CasalinoD., An advanced time approach for acoustic analogy predictions, Journal of Sound and Vibration, 2003, 261 (4), 583–612.
30.
BrentnerK.S.FarassatF., Analytical comparison of the acoustic analogy and Kirchhoff formulation for moving surfaces, American Institute of Aeronautics and Astronautics Journal, 1998, 8 (36), 1379–1386.
31.
CasalinoD.JacobM.RogerM., Prediction of rod-airfoil interaction noise using the Ffwocs Williams – Hawkings analogy, American Institute of Aeronautics and Astronautics Journal, 2003, 41 (2), 182–191.
32.
WilliamsonC.H.K., Vortex dynamics in the cylinder wake, Annual Review of Fluid Mechanics, 1996, 28, 477–539.
33.
GraftieauxL.MichardM.GrosjeanN., Combining PIV, POD, and vortex identification algorithms for the study of unsteady turbulent swirling flows, Measurement Science Techniques, 2001, 11, 1422–1429.
34.
SorgüvenE.MagagnatoF. & GabiM., Sound prediction of an airfoil in the wake of a cylinder, Proceedings of the Colloquium Euromech 449, Chamonix, 2003.
35.
GreschnerB.ThieleF.CasalinoD.JacobM.C., Influence of turbulence modelling on the broadband noise simulation for complex flows, American Institute of Aeronautics and Astronautics, AIAA Paper 2004–2926, Manchester, 2004.
