Modeling Aeolian Tones by Global Instability Modes

Prinja, Robin; Jordan, Peter; Margnat, Florent

doi:10.2514/6.2022-2917

Cited by 2 publications

(1 citation statement)

References 18 publications

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“…In previous works, promising attempts with a similar methodology were reported in Wagner et al [34,35], for a NACA0012 airfoil at a lower Reynolds number (Re = 2 × 10 4 ), and of Prinja et al [36], for the experimental flow around a cylinder. In both cases, the acoustic spectrum was dominated by a single frequency, and the analysis was focused on this discrete frequency.…”

Section: Introductionmentioning

confidence: 90%

Resolvent model for aeroacoustics of trailing-edge noise

Demange,

Yuan,

Jekosch

et al. 2023

Preprint

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This study presents a physics-based, low-order model for the trailing-edge (TE) noise generated by an airfoil at low angle of attack. The approach employs incompressible resolvent analysis of the mean flow to extract relevant spanwise-coherent structures in the transitional boundary layer and near wake. These structures are integrated into Curle's solution to Lighthill's acoustic analogy to obtain the scattered acoustic field. The model has the advantage of predicting surface pressure fluctuations from first principles, avoiding reliance on empirical models, but with a free amplitude set by simulation data. The model is evaluated for the transitional flow (Re = 5e4) around a NACA0012 airfoil at 3 deg angle of attack, which features TE noise with multiple tones. The mean flow is obtained from a compressible large eddy simulation, and spectral proper orthogonal decomposition (SPOD) is employed to extract the main hydrodynamic and acoustic features of the flow. Comparisons between resolvent and SPOD demonstrate that the physics-based model accurately captures the leading coherent structures at the main tones' frequencies, resulting in a good agreement of the reconstructed acoustic power with that of the SPOD (within 4 dB). Discrepancies are observed at high frequencies, likely linked to nonlinearities that are not considered in the resolvent analysis. The model's directivity aligns well with the data at low Helmoltz numbers, but it fails at high frequencies where the back-scattered pressure plays a significant role in directivity. This modeling approach opens the way for efficient optimization of airfoil shapes in combination with low-fidelity mean-flow solvers to reduce TE noise.

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Section: Introductionmentioning

confidence: 90%

Resolvent model for aeroacoustics of trailing-edge noise

Demange,

Yuan,

Jekosch

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Resolvent model for aeroacoustics of trailing edge noise

Demange,

Yuan,

Jekosch

et al. 2024

Theor. Comput. Fluid Dyn.

View full text Add to dashboard Cite

This study presents a physics-based, low-order model for the trailing edge (TE) noise generated by an airfoil at low angle of attack. The approach employs incompressible resolvent analysis of the mean flow to extract relevant spanwise-coherent structures in the transitional boundary layer and near wake. These structures are integrated into Curle’s solution to Lighthill’s acoustic analogy to obtain the scattered acoustic field. The model has the advantage of predicting surface pressure fluctuations from first principles, avoiding reliance on empirical models, but with a free amplitude set by simulation data. The model is evaluated for the transitional flow ($$\text {Re} = 5e4$$ Re = 5 e 4 ) around a NACA0012 airfoil at 3 deg angle of attack, which features TE noise with multiple tones. The mean flow is obtained from a compressible large eddy simulation, and spectral proper orthogonal decomposition (SPOD) is employed to extract the main hydrodynamic and acoustic features of the flow. Comparisons between resolvent and SPOD demonstrate that the physics-based model accurately captures the leading coherent structures at the main tones’ frequencies, resulting in a good agreement of the reconstructed acoustic power with that of the SPOD (within 4 dB). Discrepancies are observed at high frequencies, likely linked to nonlinearities that are not considered in the resolvent analysis. The model’s directivity aligns well with the data at low Helmholtz numbers, but it fails at high frequencies where the back-scattered pressure plays a significant role in directivity. This modeling approach opens the way for efficient optimization of airfoil shapes in combination with low-fidelity mean flow solvers to reduce TE noise. Graphical abstract

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Modeling Aeolian Tones by Global Instability Modes

Cited by 2 publications

References 18 publications

Resolvent model for aeroacoustics of trailing-edge noise

Resolvent model for aeroacoustics of trailing-edge noise

Resolvent model for aeroacoustics of trailing edge noise

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