Turbulent Friction Drag Reduction on Clark-Y Airfoil by Passive Uniform Blowing

Hirokawa, Shiho; Ohashi, Masahiro; Eto, Kaoruko; Fukagata, Koji; Tokugawa, Naoko

doi:10.2514/1.j059627

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…a perforation is well below the resolution of the presented RANS, it cannot be directly addressed within the scope of the present modelling. However, experimental studies by Hwang et al [19], at the Fukagata-Lab [36,37] and by Kornilov [22,23] showed that experimental implementations agree fairly well with the ideally uniform transpiration imposed numerically as far as boundary layer velocity distributions are concerned. Similar observations have been made for Laminar Flow Control through perforated plates, for which the effect of non-uniformity directly affects transition.…”

Section: Fig 2 Control Schemes Their Location and Schematic Of Components Of Blc-system Which Contribute Additional Drag (Blc-system Dragmentioning

confidence: 91%

Investigation of Blowing and Suction for Turbulent Flow Control on Airfoils

Fahland¹,

Stroh²,

Atzori³

et al. 2021

AIAA Journal

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An extensive parametric study of turbulent boundary layer control on airfoils via uniform blowing or suction is presented. The control is applied on either suction or pressure side of several 4-digit NACA-series airfoils. The considered parameter variations include angle of attack, Reynolds number, control intensity, airfoil camber and airfoil thickness. Two comprehensive metrics, designed to account for the additional energy required by the control, are introduced to evaluate the net aerodynamic performance enhancements. The study confirms previous findings for suction side boundary layer control and demonstrates the interesting potential

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Section: Fig 2 Control Schemes Their Location and Schematic Of Components Of Blc-system Which Contribute Additional Drag (Blc-system Dragmentioning

confidence: 91%

Investigation of Blowing and Suction for Turbulent Flow Control on Airfoils

Fahland¹,

Stroh²,

Atzori³

et al. 2021

AIAA Journal

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show abstract

“…Mickley et al [23,p. 30]) or evaluating the energy requirement of the mass-injecting control for different scenarios [25,33]. However, most studies within the field of turbulent skin friction drag reduction focus on the friction drag only leveraging canonical cases such as ducts or flat plates which do not yield other obvious drag components.…”

Section: Introductionmentioning

confidence: 99%

“…In this ideal case, there is at least some pressure difference available to overcome implementation-dependent losses (such as viscous losses of forcing the fluid through a porous surface) thus enabling a system of passive blowing as it has been described e.g. by Hirokawa [33]. Theoretically, it may also be possible to harvest the pressure difference mentioned above, as explained e.g.…”

Section: Introductionmentioning

confidence: 99%

Drag Assessment for Boundary Layer Control Schemes with Mass Injection

Fahland

Atzori

Frede

et al. 2023

Preprint

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The present study considers uniform blowing in turbulent boundary layers as active flow control scheme for drag reduction on airfoils. The focus lies on the important question of how to quantify the drag reduction potential of this control scheme correctly. It is demonstrated that mass injection causes the body drag (the drag resulting from the stresses on the body) to differ from the wake survey drag (the momentum deficit in the wake of an airfoil), which is classically used in experiments as a surrogate for the former. This difference is related to the boundary layer control (BLC) penalty, an unavoidable drag portion which reflects the effort of a mass-injecting boundary layer control scheme. This is independent of how the control is implemented. With an integral momentum budget, we show that for the present control scheme, the wake survey drag contains the BLC penalty and is thus a measure for the inclusive drag of the airfoil, i.e. the one required to determine net drag reduction. The concept of the inclusive drag is extended also to boundary layers using the von Kàrmàn equation. This means that with mass injection the friction drag only is not sufficient to assess drag reduction also in canonical flows. Large Eddy Simulations and Reynolds-averaged Navier-Stokes simulations of the flow around airfoils are utilized to demonstrate the significance of this distinction for the scheme of uniform blowing. When the inclusive drag is properly accounted for, control scenarios previously considered to yield drag reduction actually show drag increase.

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“…Using mass suction at the leading edge of a Clark-Z airfoil to provide pressurized air for blowing, Kornilov (2017) studied uniform blowing on the pressure side of the airfoil at Reynolds number Re c = U ∞ c/ν = 840 000, where U ∞ is the incoming flow velocity, c is the chord length and ν is the fluid kinematic viscosity. Eto et al (2019) studied the effects of active blowing on the suction side of a Clark-Y airfoil at Re c = 1 500 000, followed by their passive blowing study under the similar conditions (Hirokawa et al 2020). Kornilov, Kavun & Popkov (2019) employed blowing on the pressure side and suction on the suction side of an NACA0012 airfoil, and later they provided an estimation of the control energy cost under the same conditions (Kornilov 2021).…”

Section: Introductionmentioning

confidence: 99%

Decomposition of the mean friction drag on an NACA4412 airfoil under uniform blowing/suction

et al. 2021

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The application of drag-control strategies on canonical wall-bounded turbulence, such as periodic channel and zero- or adverse-pressure-gradient boundary layers, raises the question on how to distinguish consistently the origin of control effects under different reference conditions. We employ the RD identity (Renard & Deck, J. Fluid Mech., vol. 790, 2016, pp. 339–367) to decompose the mean friction drag and investigate the control effects of uniform blowing and suction applied to an NACA4412 airfoil at chord Reynolds numbers $Re_c=200\,000$ and $400\,000$ . The connection of the drag reduction/increase by using blowing/suction with the turbulence statistics (including viscous dissipation, turbulence kinetic energy production and spatial growth of the flow) across the boundary layer, subjected to adverse or favourable pressure gradients, is examined. We found that the inner and outer peaks of the contributions associated with the friction-drag generation show good scaling with either inner or outer units, respectively. They are also independent of the Reynolds number, control scheme and intensity of the blowing/suction. The small- and large-scale structures are separated with an adaptive scale-decomposition method, namely the empirical mode decomposition (EMD), which aims to analyse the scale-specific contribution of turbulent motions to friction-drag generation. Results unveil that blowing on the suction side of the airfoil is able to enhance the contribution of large-scale motions and to suppress that of small scales; however, suction behaves contrarily. The contributions related to cross-scale interactions remain almost unchanged with different control strategies.

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Turbulent Friction Drag Reduction on Clark-Y Airfoil by Passive Uniform Blowing

Cited by 8 publications

References 12 publications

Investigation of Blowing and Suction for Turbulent Flow Control on Airfoils

Investigation of Blowing and Suction for Turbulent Flow Control on Airfoils

Drag Assessment for Boundary Layer Control Schemes with Mass Injection

Decomposition of the mean friction drag on an NACA4412 airfoil under uniform blowing/suction

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