Prediction of sound generated by a rod–airfoil configuration using EASM DES and the generalised Lighthill/FW-H analogy

Abstract Sound generated by an airfoil in the wake of a rod is predicted numerically by using a Detached-Eddy Simulation (DES) unsteady flow field and a Ffowcs Williams and Hawkings acoustic analogy formulation for the far field computation. Volume sources from the rod wake are found to play a non-negligible role at high frequencies and surface contributions might be flawed if the surfaces cross highly turbulent flow regions even if surrounding volume terms are accounted for. The DES approach is based on a novel cubic explicit algebraic stress turbulence model which is built on a two-equation k–e model from Lien and Lechziner. This DES has been recently implemented at the Berlin University of Technology in the compressible Navier–Stokes flow solver ELAN. The aerodynamic results are compared to experimental data obtained at the ECL by Jacob et al., as well as to previous Large Eddy Simulations results from the Proust/Turbflow code by Boudet et al. and DES simulations from Greschner et al. based on standard turbulence models. The acoustic analogy is applied both with and without volume terms to rigid and permeable control surfaces surrounding the rod–airfoil system. Aeroacoustic results are compared to experimental data from the literature, showing that the inclusion of volume terms improves the aeroacoustic prediction in the broadband high frequency range.

[1]  S. Crow,et al.  Aerodynamic Sound Emission as a Singular Perturbation Problem , 1970 .

[2]  P. D. Francescantonio.  A NEW BOUNDARY INTEGRAL FORMULATION FOR THE PREDICTION OF SOUND RADIATION , 1997 .

[3]  Joel H. Ferziger,et al.  Computational methods for fluid dynamics , 1996 .

[4]  Frank Thiele,et al.  Investigation of Alternative Length Scale Substitutions in Detached-Eddy Simulation , 2005 .

[5]  P. Spalart.  Comments on the feasibility of LES for wings, and on a hybrid RANS/LES approach , 1997 .

[6]  Damiano Casalino,et al.  A rod-airfoil experiment as a benchmark for broadband noise modeling , 2005 .

[7]  Damiano Casalino,et al.  Prediction of Rod-Airfoil Interaction Noise Using the Ffowcs-Williams-Hawkings Analogy , 2003 .

[8]  P. Spalart,et al.  A New Version of Detached-eddy Simulation, Resistant to Ambiguous Grid Densities , 2006 .

[9]  F. Farassat,et al.  An Analytical Comparison of the Acoustic Analogy and Kirchhoff Formulation for Moving Surfaces , 1997 .

[10]  Frank Thiele,et al.  Guidelines for implementing Detached-Eddy Simulation using different models , 2007 .

[11]  G. P. Succi,et al.  The prediction of helicopter rotor discrete frequency noise , 1982 .

[12]  M. Lighthill.  On sound generated aerodynamically I. General theory , 1952, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[13]  Frank Thiele,et al.  Prediction of the spreading mechanism of 3D turbulent wall jets with explicit Reynolds–stress closures , 2003 .

[14]  Jérôme Boudet,et al.  Wake-Airfoil Interaction as Broadband Noise Source: A Large-Eddy Simulation Study , 2005 .

[15]  M. Wolfshtein.  The velocity and temperature distribution in one-dimensional flow with turbulence augmentation and pressure gradient , 1969 .

[16]  Frank Thiele,et al.  Turbulence Modelling in Application to The Vortex Shedding of Stalled Airfoils , 2005 .

[17]  D. Casalino.  An advanced time approach for acoustic analogy predictions , 2003 .

[18]  D. L. Hawkings,et al.  Sound generation by turbulence and surfaces in arbitrary motion , 1969, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[19]  H. Fujita,et al.  Numerical prediction of aerodynamic noise radiated from low Mach number turbulent wake , 1993 .

[20]  Frank Thiele,et al.  Influence of turbulence modeling on the broadband noise simulation for complex flows , 2004 .

[21]  Fue-Sang Lien,et al.  COMPUTATIONAL MODELLING OF 3D TURBULENT FLOW IN S-DIFFUSER AND TRANSITION DUCTS , 1993 .

[22]  C. Bogey.  Three-dimensional non-refrective boundary conditions for acoustic simulation : far field formulation and validation test cases , 2002 .