Active and Natural Suction at Forward-Facing Steps for Delaying Laminar–Turbulent Transition

Zahn, Johannes; Rist, Ulrich

doi:10.2514/1.j055122

Cited by 16 publications

(16 citation statements)

References 12 publications

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“…This was predicted also in numerical studies as presented in [17]. In addition to that, note that the transition front is not as straight as without suction and appears frayed (compare figure 7).…”

Section: Reproducibility and Repeatability Of The Resultssupporting

confidence: 79%

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Experimental analysis of suction on step-induced boundary-layer transition

Dimond

Costantini

Risius

et al. 2019

Experimental Thermal and Fluid Science

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The influence of suction on step-induced boundary-layer transition has been experimentally investigated in the Cryogenic Ludwieg-Tube Goettingen at large chord Reynolds numbers (up to 16 • 10 6), Mach numbers from 0.35 to 0.77 and various streamwise pressure gradients by means of temperature-sensitive paint. Surface imperfections, implemented as combination of gap and forward-facing step, caused transition to occur at a location more upstream than in the case of a smooth surface (i.e. without gap and step). For this combination of imperfections, it was demonstrated for the first time in experiments that suction, achieved passively by exploiting the pressure difference between upper and lower side of the model, induced a movement of transition to a more downstream location than without suction, and in most cases even more downstream than on the smooth configuration at the same test conditions. Thus, the effect of suction was to even overcompensate the adverse effect of the combination of gap and forward-facing step on boundary-layer transition for the investigated test conditions.

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Section: Reproducibility and Repeatability Of The Resultssupporting

confidence: 79%

“…slits) downstream of a backward facing step at low Mach numbers (M < 0.1); numerical studies have been 45 conducted to examine suction through a gap upstream of a forward-facing step in refs. [17], [18] and [19]…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of suction on step-induced boundary-layer transition

Dimond

Costantini

Risius

et al. 2019

Experimental Thermal and Fluid Science

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“…where the subscript notations of gap and clean again refers to solutions over the deformed and nondeformed geometries. (A similar analysis was undertaken in the studies of other surface deformations [14,21,23,35,37,38,42].) Figure 9 displays N-factor variations for all of the deformations modeled in this study and for 10 −7 R ∞ 1.223.…”

Section: Amplification Of Nmentioning

confidence: 73%

“…Further studies on surface deformations have examined the effect of humps [29][30][31][32], dimples [33], corrugation [34], steps [35][36][37][38][39], roughness distributions [40,41], and deep gaps [42]. More recently, Xu et al [43] studied the impact of three-dimensional surface indentations on the destabilization of TS disturbances, where separation bubbles could form within sufficiently deformed indentations.…”

Section: Introductionmentioning

confidence: 99%

Effect of Small Surface Deformations on the Stability of Tollmien–Schlichting Disturbances

et al. 2018

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The effect of a small Gaussian shaped deformation on the development and growth of Tollmien-Schlichting disturbances on an unswept airfoil is investigated. A broad range of gap depths and widths is modeled that can be sufficient to generate localized pockets of reverse flow. Boundary-layer profiles are computed using a Navier-Stokes solver, permitting a thorough investigation of all configurations considered. The linear stability of Tollmien-Schlichting waves is then examined using parabolized stability equations and linearized Navier-Stokes formulations, with the former method giving excellent agreement with the latter for all disturbances studied, including within separated boundary layers. Tollmien-Schlichting disturbances are amplified by deeper and wider gaps, with a correlation derived by relating the increase in the N factor with the gap dimensions and freestream Reynolds number.

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“…Recently, alternatives such as direct numerical simulation (DNS) of transitional modes have shown promising results for the understanding of the physical background under special flow conditions such as geometrically singular cases, where physical fundamentals of classic LST are not valid. A typical geometric singularity of this class is the forward or backward facing step, violating the parallel flow assumption at corners that require a special singularity treatment, as demonstrated by Zahn, Edelmann and Rist [2,3]. For Tollmien-Schlichting modes (TS-modes), a two-dimensional approach of the perturbed boundary layer flow-field is not very time-consuming and allows the direct investigation of TS-modes over even complicated geometries, including non-linear growth effects.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of TS-waves over suction panel steps from manufacturing tolerances

Lüdeke¹,

Soldenhoff²

2021

CEAS Aeronaut J

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To determine allowable tolerances between successive suction panels at hybrid laminar wings with suction surfaces, direct numerical simulations of Tollmien–Schlichting waves over different steps are carried out for realistic suction rates on a wind tunnel configuration. Simulations at given suction panel positions over forward and backward facing steps are carried out by the use of a high-order method for the direct simulation of Tollmien–Schlichting wave growth. Comparisons between high-fidelity direct numerical simulations and quick linear stability calculations have shown capabilities and limits of the well-validated linear stability theory design approach.

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Active and Natural Suction at Forward-Facing Steps for Delaying Laminar–Turbulent Transition

Cited by 16 publications

References 12 publications

Experimental analysis of suction on step-induced boundary-layer transition

Experimental analysis of suction on step-induced boundary-layer transition

Effect of Small Surface Deformations on the Stability of Tollmien–Schlichting Disturbances

Direct numerical simulation of TS-waves over suction panel steps from manufacturing tolerances

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