Unsteady slat wake characteristics of a 2-D high-lift configuration

Paschal, Keith B.; Jenkins, Lutyer; Yao, Chung-Sheng

doi:10.2514/6.2000-139

Cited by 38 publications

(16 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Although there is no direct impingement of these streamwise oriented vortices on the leading edge of the main wing, these eddies are advected and affect the flow over the main element as will be discussed later. These findings corroborate the PIV measurements of different teams in North America (Paschal, Jenkins & Yao 2000;Jenkins et al 2004) As recalled earlier, only few papers (see table 2) investigated the flow dynamics over the flap while a detailed understanding of the intricate flow physics around the whole three-element aerofoil is needed. In particular, the flow field over the wing/flap region is not well understood and difficult to predict.…”

Section: Instantaneous Flowsupporting

confidence: 88%

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

Deck

Laraufie

2013

J. Fluid Mech.

View full text Add to dashboard Cite

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.

show abstract

Section: Instantaneous Flowsupporting

confidence: 88%

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

Deck

Laraufie

2013

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…2); it has a rich history of previous investigations, including the studies performed in the context of a CFD challenge sponsored by NASA Langley in 1993 [20] as well as additional, follow-up studies as described in Refs. [24,[27][28][29]. The slat chord and flap chord of the 30P30N model are equal to 15% and 30%, respectively, of the stowed chord.…”

Section: A Geometry Of High-lift Configuration and Flow Conditionsmentioning

confidence: 99%

“…We recall that, based on an earlier set of measurements in BART with the same 30P30N model, Ref. [29] had reported observing some PIV images that were "indicative of a streamwise vortex emanating from the slat cove." The convected slat cove structures interact with the smaller scale vortices shed behind the relatively thin slat trailing edge (0.36 mm in thickness), as well as perturbing the wing boundary layer beneath them.…”

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

confidence: 99%

Slat Cove Unsteadiness: Effect of 3D Flow Structures

Choudhari

Khorrami

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

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.

show abstract

“…10,14 Blowing tubes placed in the juncture may also be used to help improve the situation. 15,16 Blowing tubes were not used during the current entry of the GTRI model, but may be needed in the future in order to achieve two-dimensionality at higher jet momentum coefficients.…”

Section: Spanwise Flow Uniformitymentioning

confidence: 99%