Unsteady aerodynamics of slat cove flow in a high-lift device configuration

Takeda, Kenji; Ashcroft, Graham; Zhang, X.; Nelson, P.A.

doi:10.2514/6.2001-706

Cited by 45 publications

(22 citation statements)

References 1 publication

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“…Specifically, the 2D computations 19 sought to evaluate the accuracy of the previously employed zonal turbulence model, 15 in which the turbulence production term was switched off within the slat cove region. Consistent with the assessment in [16], the results of these computations 19 indicated excessively energetic vorticity structures in comparison with the PIV measurements, 23 regardless of the main element angle-of-attack within the range of 4 to 8 degrees. No major improvements were noted in an additional set of 2D computations involving modifications to the zonal model, such as either a partial restoration of turbulence production within a thin region adjacent to the lower slat surface or a 2D implementation of a RANS-LES hybrid model.…”

Section: Introductionsupporting

confidence: 73%

“…7). This behavior is also representative of the measurements reported in [23] for a different high-lift configuration. The 3D predictions in Fig.…”

Section: A Instantaneous Flow-field: 3d Vs 2d Predictionssupporting

confidence: 67%

“…Indeed, the discrepancies related to the TKE distribution had been cited in our earlier work 16 as one of the major weaknesses of the 2D predictions based on the same pseudo-laminar treatment of the slat cove region. The qualitative agreement between the 3D solution and the PIV data makes the TKE distribution based on the time accurate calculations more consistent with both experiments 22,23 and the predictions based on stationary RANS calculations with a two-equation turbulence model 16 .…”

Section: Tke Distributionmentioning

confidence: 75%

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Slat Cove Unsteadiness: Effect of 3D Flow Structures

Choudhari

Khorrami

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

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Our previous studies have indicated that 2D, time accurate computations based on a pseudo-laminar zonal model of the slat cove region (within the framework of the Reynolds-Averaged Navier-Stokes equations) are inadequate for predicting the full unsteady dynamics of the slat cove flow field. Even though such computations could capture the large-scale, unsteady vorticity structures in the slat cove region without requiring any external forcing, the simulated vortices were excessively strong and the recirculation zone was unduly energetic in comparison with the PIV measurements for a generic high-lift configuration. To resolve this discrepancy and to help enable physics based predictions of slat aeroacoustics, the present paper is focused on 3D simulations of the slat cove flow over a computational domain of limited spanwise extent. Maintaining the pseudo-laminar approach, current results indicate that accounting for the threedimensionality of flow fluctuations leads to considerable improvement in the accuracy of the unsteady, nearfield solution. Analysis of simulation data points to the likely significance of turbulent fluctuations near the reattachment region toward the generation of broadband slat noise. The computed acoustic characteristics (in terms of the frequency spectrum and spatial distribution) within short distances from the slat resemble the previously reported, subscale measurements of slat noise.

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Section: Introductionsupporting

confidence: 73%

“…7). This behavior is also representative of the measurements reported in [23] for a different high-lift configuration. The 3D predictions in Fig.…”

Section: A Instantaneous Flow-field: 3d Vs 2d Predictionssupporting

confidence: 67%

Section: Tke Distributionmentioning

confidence: 75%

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Slat Cove Unsteadiness: Effect of 3D Flow Structures

Choudhari

Khorrami

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

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“…and Europe(Takeda et al 2001b;Arnott et al 2003) as well as in several numerical studies (seetable 2).…”

mentioning

confidence: 99%

Numerical investigation of the flow dynamics past a three-element aerofoil

Deck

Laraufie

2013

J. Fluid Mech.

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A numerical investigation of the flow dynamics around a two-dimensional high-lift configuration was carried out by means of a zonal detached eddy simulation (ZDES) technique for flow conditions corresponding to aircraft approach. Both slat and flap regions have been scrutinized and compared with experimental data available in the literature. It is shown that slat and flap coves behave like shallow cavities. The distance between the upstream cusp and the downstream edge is the relevant length scale for each cove taken separately. Consistently with previous findings, this study indicates that the maximum of the broadband spectrum of slat (respectively flap) pressure fluctuations occurs for Strouhal numbers 0.5 St 4 when based on slat chord (respectively on flap chord) and free-stream velocity. It is shown that mode (n) of the slat cove and mode (n + 1) of the flap cove are very close making a coherent phase relationship possible. A large-scale coupled self-sustained oscillations mechanism between slat and flap cavities, evidenced by spectral analysis, occurs at a Strouhal number St = 3-6 based on the main wing chord and free-stream velocity. This yields to an acoustic feedback mechanism characterized by a normalized frequency depending on the free stream Mach number like St = (1 − M 2 0 )/2M 0 . The present result appears to line up with the findings by Hein et al. (J. Fluid Mech., vol. 582, 2007, pp. 179-202) who showed that two types of resonance could exist: surface waves ones, scaling with the total aerofoil length and longitudinal cavity-type resonances, scaling with the slat cove length.

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“…The high-frequency tonal sound, which can be extremely loud, is caused by shed vortices from the finite-thickness trailing edge 11,12 . Extensive computational simulations [13][14][16][17][18] in conjunction with particle image velocimetry measurements 15,19 of the slat cove flow field have revealed the cause and the effect between the coherent structures of the free-shear layer at the cusp and the lowfrequency broadband component of the acoustic spectrum.…”

Section: Introductionmentioning

confidence: 99%