Current state and prospects of researches on the control of turbulent boundary layer by air blowing

Kornilov, V. I.

doi:10.1016/j.paerosci.2015.05.001

Cited by 87 publications

(28 citation statements)

References 70 publications

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“…More recent studies confirmed this possibility, investigating the effects of MBT on more complex geometries as well as on turbulent boundary layers subject to adverse-pressure gradients. For a detailed description of the development of the MBT technique, we refer to the review by Hwang (2004), whereas Kornilov (2015) discusses more recent advancements, focusing on experimental results.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic Effects of Uniform Blowing and Suction on a NACA4412 Airfoil

Atzori

Vinuesa

Fahland

et al. 2020

Flow Turbulence Combust

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We carried out high-fidelity large-eddy simulations to investigate the effects of uniform blowing and uniform suction on the aerodynamic efficiency of a NACA4412 airfoil at the moderate Reynolds number based on chord length and incoming velocity of Re c = 200,000 . We found that uniform blowing applied at the suction side reduces the aerodynamics efficiency, while uniform suction increases it. This result is due to the combined impact of blowing and suction on skin friction, pressure drag and lift. When applied to the pressure side, uniform blowing improves aerodynamic efficiency. The Reynoldsnumber dependence of the relative contributions of pressure and friction to the total drag for the reference case is analysed via Reynolds-averaged Navier-Stokes simulations up to Re c = 10,000,000 . The results suggest that our conclusions on the control effect can tentatively be extended to a broader range of Reynolds numbers.

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Section: Introductionmentioning

confidence: 99%

Aerodynamic Effects of Uniform Blowing and Suction on a NACA4412 Airfoil

Atzori

Vinuesa

Fahland

et al. 2020

Flow Turbulence Combust

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“…Many of these applications typically take place at high Reynolds numbers, and a wealth of systems and techniques to reduce turbulent skin friction drag has been proposed over many years. In practice, only very few of these systems and techniques have been implemented to a successful extent, and many of them appear to be subject to a performance loss as the Reynolds number increases, as well as other technical constraints (Bushnell 2002;García-mayoral & Jiménez 2011;Quadrio 2011;Kornilov 2015). At low Reynolds numbers, the origin of turbulent skin friction has been inextricably linked to the near-wall region.…”

Section: Introductionmentioning

confidence: 99%

Skin-friction generation by attached eddies in turbulent channel flow

2016

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Despite a growing body of recent evidence on the hierarchical organization of the selfsimilar energy-containing motions in the form of Townsend’s attached eddies in wallbounded turbulent flows, their role in turbulent skin-friction generation is currently known very little. In this paper, the contribution of each of these self-similar energycontaining motions to turbulent skin friction is explored up to Reτ ≃ 4000. Three different approaches are employed to quantify the skin-friction generation by the motions, the spanwise length scale of which is smaller than a given cut-off wavelength: 1) FIK identity in combination with the spanwise wavenumber spectra of the Reynolds shear stress; 2) confinement of the spanwise computational domain; 3) artificial damping of the motions to be examined. The near-wall motions are found to continuously lose their role in skin-friction generation on increasing the Reynolds number, consistent with the previous finding at low Reynolds numbers. The largest structures given in the form of very-large-scale and large-scale motions are also found to be of limited importance: due to a non-trivial scale-interaction process, their complete removal yields only 5 ∼ 8% of skin-friction reduction at all the Reynolds numbers considered, although they are found to be responsible for 20 ∼ 30% of total skin friction at Reτ ≃ 2000. Application of all the three approaches consistently reveals that the largest amount of skin friction is generated by the self-similar motions populating the logarithmic region. It is further shown that the contribution of these motions to turbulent skin friction gradually increases with the Reynolds number, and that these coherent structures are eventually responsible for most of turbulent skin-friction generation at sufficiently high Reynolds numbers

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“…Numerous control strategies exist to prevent separation, 885 A8-2 Y. B. Broekema, R. J. Labeur and W. S. J. Uijttewaal including streamlining of a flow body (Schlichting 1951;Schubauer & Spangenberg 1960), boundary layer suction (Prandtl 1935;Truckenbrodt 1956;Kametani et al 2015;Kornilov 2015), injection of momentum into the boundary layer (Wallis & Stuart 1958) and controlling separation by provoking it (Hurley 1961;Francis et al 1979). In this paper we present observations that demonstrate -for the first timethat vertical flow separation over steep slopes in open channels may be suppressed by a lateral gradient in the streamwise velocity field upstream of the slope.…”

Section: Introductionmentioning

confidence: 99%