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Airfoil Tonal Noise Prediction Using Urans

Witold Klimczyk
Witold Klimczyk
 e 
Adam Sieradzki
Adam Sieradzki
   | 08 dic 2023
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Article Category: original article
Pubblicato online: 08 dic 2023
Pagine: 1 - 17
Ricevuto: 22 nov 2022
Accettato: 11 set 2023
DOI: https://doi.org/10.2478/tar-2023-0019
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© 2023 Witold Klimczyk et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1.

Mechanism of LBL, indicating VS noise generation. LBL, Laminar boundary layer. VS, vortex shedding.
Mechanism of LBL, indicating VS noise generation. LBL, Laminar boundary layer. VS, vortex shedding.

Figure 2.

Computational domain schematic view with boundary conditions.
Computational domain schematic view with boundary conditions.

Figure 3.

Mesh around the airfoil.
Mesh around the airfoil.

Figure 4.

Mesh close up: maximum thickness of the near wall region at the airfoil.
Mesh close up: maximum thickness of the near wall region at the airfoil.

Figure 5.

Mesh around the rear part of the airfoil.
Mesh around the rear part of the airfoil.

Figure 6.

Aeroacoustics using hybrid approach with Lighthill analogy. URANS, unsteady Reynolds-averaged Navier–Stokes.
Aeroacoustics using hybrid approach with Lighthill analogy. URANS, unsteady Reynolds-averaged Navier–Stokes.

Figure 7.

Acoustic FE mesh: domain (left) and close up to the airfoil (right). Sources are calculated in the yellow zone and acoustic waves are propagated in the entire domain.
Acoustic FE mesh: domain (left) and close up to the airfoil (right). Sources are calculated in the yellow zone and acoustic waves are propagated in the entire domain.

Figure 8.

Turbulence intensity around the airfoil dissipated from 2% at the inlet.
Turbulence intensity around the airfoil dissipated from 2% at the inlet.

Figure 9.

Instantaneous pressure coefficient at the rear part of the airfoil for different levels of turbulence.
Instantaneous pressure coefficient at the rear part of the airfoil for different levels of turbulence.

Figure 10.

Pressure contours around the rear part of the airfoil for cases with 0.18% (left) and 0.65% (right) turbulence intensities.
Pressure contours around the rear part of the airfoil for cases with 0.18% (left) and 0.65% (right) turbulence intensities.

Figure 11.

Snapshots of the formation of hydrodynamic instabilities in the boundary layer of S834 airfoil captured with URANS for TI = 0.18%. Lines join the vortical structures to help track their movement over the airfoil.
Snapshots of the formation of hydrodynamic instabilities in the boundary layer of S834 airfoil captured with URANS for TI = 0.18%. Lines join the vortical structures to help track their movement over the airfoil.

Figure 12.

The vortical structures over pressure and suction sides of the airfoil as identified by q-criterion. The lines join vortices in three snapshots, showing the origin of different frequencies on both sides of the airfoil.
The vortical structures over pressure and suction sides of the airfoil as identified by q-criterion. The lines join vortices in three snapshots, showing the origin of different frequencies on both sides of the airfoil.

Figure 13.

Frequency domain of drag monitor for the low turbulence case. The peak frequency of 1,300 Hz and secondary frequency of 1,660 Hz match the frequencies of pressure and suction side pressure oscillations.
Frequency domain of drag monitor for the low turbulence case. The peak frequency of 1,300 Hz and secondary frequency of 1,660 Hz match the frequencies of pressure and suction side pressure oscillations.

Figure 14.

Summary of peak amplitudes of pressure fluctuations at two chord locations for the pressure side (ps) and the suction side (ss) depending on the turbulence intensity. Increasing turbulence affects pressure oscillations, which are only present at the lowest turbulence on the pressure side and disappear from the suction side at TI = 0.73%.
Summary of peak amplitudes of pressure fluctuations at two chord locations for the pressure side (ps) and the suction side (ss) depending on the turbulence intensity. Increasing turbulence affects pressure oscillations, which are only present at the lowest turbulence on the pressure side and disappear from the suction side at TI = 0.73%.

Figure 15.

Acoustic pressure field around the airfoil (in Pascals) for the baseline case at the frequency of 1,600 Hz (i.e. the peak tone frequency). The origin of acoustic waves at the trailing edge is clearly visible, as is the directivity of emitted noise.
Acoustic pressure field around the airfoil (in Pascals) for the baseline case at the frequency of 1,600 Hz (i.e. the peak tone frequency). The origin of acoustic waves at the trailing edge is clearly visible, as is the directivity of emitted noise.

Figure 16.

PWL from URANS and Lighthill analogy (CAA) compared to the experimental measurements (EXP). CAA, computational aeroacoustics; EXP, URANS, unsteady Reynolds-averaged Navier–Stokes.
PWL from URANS and Lighthill analogy (CAA) compared to the experimental measurements (EXP). CAA, computational aeroacoustics; EXP, URANS, unsteady Reynolds-averaged Navier–Stokes.

Comparison of frequencies and amplitudes of drag oscillations for the baseline case (32 m/s) and additional cases at 22.4 m/s and 479 m/s, together with presentation of the experimental data pertaining to peak tone frequency (1/3 octave band centre) and PWL for comparison.

u∞ [m/s] TI fD [Hz] Amplitude, drag counts fpeak, EXP [Hz] PWLEXP [dB]
22.4 0.44% 1,120 0.18 1,000 69.36
32.0 0.65% 1,620 0.74 1,600 71.32
47.9 0.69% 2,560 1.88 2,508 71.44

Case summary.

u∞ 22.4, 32, 47.9 [m/s]
ρ 1.225 [kg/m3]
Re 5×105 [–]
α 4.4 [°]
c 0.2286 [m]
TILE 0.18%–0.99%

Summary of peak tone frequencies and amplitudes for pressure signals collected at points at 96% chord and drag signal.

Turbulence Intensity Suction side, 96% chord Pressure side, 96% chord Force (drag), airfoil
Frequency [Hz] Amplitude [Pa] Frequency [Hz] Amplitude [Pa] Frequency [Hz] Amplitude (drag counts)
0.18% 1,660 5.1 1,300 9.6 1,300 1.7
0.25% 1,660 6.1 1,660 1.1 1,660 0.74
0.65% 1,620 5.0 1,620 0.6 1,620 0.66
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