Effect of wall suction on leading edge contamination

Arnal, D.; Juillen, J. C.; Reneaux, J.; Гаспарян, Г. Д.

doi:10.1016/s1270-9638(97)90000-6

Cited by 32 publications

(22 citation statements)

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“…However, transition is regularly observed in experiments above the significantly lower value Re tr ≈ 250 (Gaster 1967;Poll 1979;Arnal et al 1997), if the flow is subject to sufficiently large disturbances, as confirmed in the simulations by Spalart (1988) and Dimas, Mowli & Piomelli (2003). Experiments by Gaster (1967) and Pfenninger (1977) led to the hypothesis of leading-edge contamination, i.e.…”

mentioning

confidence: 69%

“…To this end we analyse the transition Reynolds number Re tr at which turbulent flow can first be observed and its dependence on the wall suction strength κ. It is known that wall suction (κ > 0) stabilizes the attachment-line flow both by extending the region of primary linear stability (Hall et al 1984;Joslin 1995) and by inhibiting the transition to turbulence (Spalart 1988;Arnal et al 1997).…”

Section: Comparison Of Dns Results To Experiments and Simulations Fromentioning

confidence: 99%

“…With κ denoting its non-dimensional strength, wall suction is known to increase both the linear critical Reynolds number Re crit (κ) (Hall et al 1984) and the transition Reynolds number Re tr (κ) (Spalart 1988;Arnal et al 1997). This behaviour was linked to the linear stability theory of a broader class of homogeneous flat-plate boundary layers by John, Obrist & Kleiser (2012, 2014a.…”

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confidence: 99%

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Secondary instability and subcritical transition of the leading-edge boundary layer

2016

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The leading-edge boundary layer (LEBL) in the front part of swept airplane wings is prone to three-dimensional subcritical instability, which may lead to bypass transition. The resulting increase of airplane drag and fuel consumption implies a negative environmental impact. In the present paper, we present a temporal biglobal secondary stability analysis (SSA) and direct numerical simulations (DNS) of this flow to investigate a subcritical transition mechanism. The LEBL is modelled by the swept Hiemenz boundary layer (SHBL), with and without wall suction. We introduce a pair of steady, counter-rotating, streamwise vortices next to the attachment line as a generic primary disturbance. This generates a high-speed streak, which evolves slowly in the streamwise direction. The SSA predicts that this flow is unstable to secondary, time-dependent perturbations. We report the upper branch of the secondary neutral curve and describe numerous eigenmodes located inside the shear layers surrounding the primary high-speed streak and the vortices. We find secondary flow instability at Reynolds numbers as low as Re ≈ 175, i.e. far below the linear critical Reynolds number Re crit ≈ 583 of the SHBL. This secondary modal instability is confirmed by our three-dimensional DNS. Furthermore, these simulations show that the modes may grow until nonlinear processes lead to breakdown to turbulent flow for Reynolds numbers above Re tr ≈ 250. The three-dimensional mode shapes, growth rates, and the frequency dependence of the secondary eigenmodes found by SSA and the DNS results are in close agreement with each other. The transition Reynolds number Re tr ≈ 250 at zero suction and its increase with wall suction closely coincide with experimental and numerical results from the literature. We conclude that the secondary instability and the transition scenario presented in this paper may serve as a possible explanation for the well-known subcritical transition observed in the leading-edge boundary layer.

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confidence: 69%

Section: Comparison Of Dns Results To Experiments and Simulations Fromentioning

confidence: 99%

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confidence: 99%

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Secondary instability and subcritical transition of the leading-edge boundary layer

2016

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“…These wedge-shapes regions can also form downstream of the impact location, where a small delay in the transition of the boundary layer occurs. For a swept wing, it is particularly important to avoid disturbances near the attachment line as this could adversely affect laminar flow over the entire outboard region of the surface and consequent increase in drag [23,[26][27][28].…”

Section: Critical Height To Transitionmentioning

confidence: 99%

Critical considerations in the mitigation of insect residue contamination on aircraft surfaces – A review

Kok

Smith

Wohl

et al. 2015

Progress in Aerospace Sciences

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“…This subcritical instability, which may cause turbulence immediately downstream of the leading edge, occurs independently of the classical Tollmien-Schlichting (TS) and cross-flow bypass transition scenarios (Owen & Randall 1952;Saric et al 2003). Understanding the transition processes of this boundary layer at the leading-edge of a swept wing is a crucial step towards delaying or inhibiting the onset of turbulence along the wing, and thus towards a reduction of airplane drag and fuel consumption (Arnal et al 1997). As yet, these processes are not fully understood and attempts to explain the transition comprise elaborate linear biglobal stability analyses (Theofilis et al 2003;Robitaillié-Montané 2005) and numerical simulations of secondary instability phenomena (Obrist, Henniger & Kleiser 2012).…”

Section: Introductionmentioning

confidence: 99%

A class of exact Navier–Stokes solutions for homogeneous flat-plate boundary layers and their linear stability

2014

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We introduce a new boundary layer formalism on the basis of which a class of exact solutions to the Navier-Stokes equations is derived. These solutions describe laminar boundary layer flows past a flat plate under the assumption of one homogeneous direction, such as the classical swept Hiemenz boundary layer (SHBL), the asymptotic suction boundary layer (ASBL) and the oblique impingement boundary layer. The linear stability of these new solutions is investigated, uncovering new results for the SHBL and the ASBL. Previously, each of these flows had been described with its own formalism and coordinate system, such that the solutions could not be transformed into each other. Using a new compound formalism, we are able to show that the ASBL is the physical limit of the SHBL with wall suction when the chordwise velocity component vanishes while the homogeneous sweep velocity is maintained. A corresponding non-dimensionalization is proposed, which allows conversion of the new Reynolds number definition to the classical ones. Linear stability analysis for the new class of solutions reveals a compound neutral surface which contains the classical neutral curves of the SHBL and the ASBL. It is shown that the linearly most unstable Görtler-Hämmerlin modes of the SHBL smoothly transform into Tollmien-Schlichting modes as the chordwise velocity vanishes. These results are useful for transition prediction of the attachment-line instability, especially concerning the use of suction to stabilize boundary layers of swept-wing aircraft.

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Effect of wall suction on leading edge contamination

Cited by 32 publications

References 1 publication

Secondary instability and subcritical transition of the leading-edge boundary layer

Secondary instability and subcritical transition of the leading-edge boundary layer

Critical considerations in the mitigation of insect residue contamination on aircraft surfaces – A review

A class of exact Navier–Stokes solutions for homogeneous flat-plate boundary layers and their linear stability

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