Development of Turbulence Model to Simulate Drag Reducing Effects of Riblets

Okabayashi, Kie; Matsue, Takanori; Asai, Masahito

doi:10.2322/jjsass.64.41

Cited by 4 publications

(5 citation statements)

References 17 publications

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“…For example, some structural units can be transformed into structures having surface asperities and asymmetric structures such as airfoil-like geometries, including the structural union of these geometries of different sizes. Such deformability gives the structural materials unique functionality across multiple length-scales, such as enhanced frictional resistance due to an increase in real contact area5556 and improved lifting performance with reduced drag effects575859.…”

Section: Discussionmentioning

confidence: 99%

Orthotropic Laminated Open-cell Frameworks Retaining Strong Auxeticity under Large Uniaxial Loading

Tanaka

Suga

Iwata

et al. 2017

Sci Rep

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Anisotropic materials form inside living tissue and are widely applied in engineered structures, where sophisticated structural and functional design principles are essential to employing these materials. This paper presents a candidate laminated open-cell framework, which is an anisotropic material that shows remarkable mechanical performance. Using additive manufacturing, artificial frameworks are fabricated by lamination of in-plane orthotropic microstructures made of elbowed beam and column members; this fabricated structure features orthogonal anisotropy in three-dimensional space. Uniaxial loading tests reveal strong auxeticity (high negative Poisson’s ratios) in the out-of-plane direction, which is retained reproducibly up to the nonlinear elastic region, and is equal under tensile and compressive loading. Finite element simulations support the observed auxetic behaviors for a unit cell in the periodic framework, which preserve the theoretical elastic properties of an orthogonal solid. These findings open the possibility of conceptual materials design based on geometry.

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Section: Discussionmentioning

confidence: 99%

Orthotropic Laminated Open-cell Frameworks Retaining Strong Auxeticity under Large Uniaxial Loading

Tanaka

Suga

Iwata

et al. 2017

Sci Rep

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“…The minimum probe diameter employed in the present study was 0.5 mm. The direction where the pitot-rakes were aligned was determined by assuming that the pitot-rakes were located on the streamline along the fuselage which was estimated by numerical simulation [17]. Note that an actual streamline can vary depending on flight conditions and, hence, the location of the pitot-rake may not be aligned with the flow.…”

Section: Flight Test Bed and Measurement System Onboardmentioning

confidence: 99%

“…The riblet shape was a straight groove shape, the width of which is 170 µm. More details of the riblet used in the flight experiment can be found elsewhere [17,22,38] as this study emphasizes the interpolation of the boundary layer profiles measured under flight conditions.…”

Section: Paint-based Ribletsmentioning

confidence: 99%

“…The 3M company demonstrated that their riblets successfully reduced skin friction drag 4-6% in the flowfield without involving any pressure gradients or angles of attack [16]. With the aid of computer simulation and highly resolved measurement techniques, the reduction of skin friction drag by riblets has been found to reach approximately 10% by optimizing the riblet geometry to cope with the flowfield of interest [17][18][19][20]. With regard to an actual application of riblets on aircraft, the Airbus company has implemented wind tunnel tests for actual aircraft with riblets attached to the whole airframe surface, and consequently demonstrated the reduction of skin friction drag by approximately 2% [1,21].…”

Section: Introductionmentioning

confidence: 99%

“…The Japan Aerospace Exploration Agency (JAXA) has been investigating the effectiveness of riblets in reducing skin friction drag [22,23] as part of their environmentally friendly aircraft research project known as Flight Investigation of skiN-friction reducing Eco-coating (FINE). The aims of the riblet study are (i) to develop paint-based riblets using aviation paint, and (ii) to optimize the riblet geometry so as to gain reduction capability of skin friction drag for JAXA's originally designed riblet [17].…”

Section: Introductionmentioning

confidence: 99%

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Interpolation of Turbulent Boundary Layer Profiles Measured in Flight Using Response Surface Methodology

et al. 2018

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Turbulent boundary layer profiles on the aircraft surface were characterized by pitot-rake measurements conducted in flight experiments at high subsonic Mach number ranges. Due to slight variations in atmospheric air conditions or aircraft attitudes, such as angles of attack and absolute flight speeds at different flights even under the same premised flight conditions, the boundary layer profiles measured at different flights can exhibit different shape and velocity values. This concern leads to difficulty in evaluating the efficiency of using some kind of drag-controlling device such as riblets in the flight test, since the evaluation would be conducted by comparing the profiles measured with and without using riblets at different flights. An approach was implemented to interpolate the boundary layer profile for a flight condition of interest based on the response surface method, in order to eliminate the influence of the flight conditional difference. Results showed that the interpolation with the 3rd-degree response surface model with a combination of two independent variables of flight Mach number and total pressure successfully eliminated the influence of the flight conditional difference, and interpolated the boundary layer profiles measured at different flights within an inaccuracy of 4.1% for the flight Mach number range of 0.5 to 0.78.

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Evaluation of Skin Friction Drag Reduction in Turbulent Boundary Layer Using Riblets

Takahashi

Kurita

Koga

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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A unique approach to evaluate the reduction of skin friction drag by riblets was applied to boundary layer profiles measured in wind tunnel experiments. The proposed approach emphasized the turbulent scales based on hot-wire anemometry data obtained at a sampling frequency of 20 kHz in the turbulent boundary layer to evaluate the skin friction drag reduction. Three-dimensional riblet surfaces were fabricated using aviation paint and were applied to a flat-plate model surface. The turbulent statistics, such as the turbulent scales and intensities, in the boundary layer were identified based on the freestream velocity data obtained from the hot-wire anemometry. Those turbulent statistics obtained for the riblet surface were compared to those obtained for a smooth flat plate without riblets. Results indicated that the riblet surface increased the integral scales and decreased the turbulence intensity, which indicated that the turbulent structure became favorable for reducing skin friction drag. The proposed method showed that the current three-dimensional riblet surface reduced skin friction drag by about 2.8% at a chord length of 67% downstream of the model's leading edge and at a freestream velocity of 41.7 m/s (Mach 0.12). This result is consistent with that obtained by the momentum integration method based on the pitot-rake measurement, which provided a reference dataset of the boundary layer profile.

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Development of Turbulence Model to Simulate Drag Reducing Effects of Riblets

Cited by 4 publications

References 17 publications

Orthotropic Laminated Open-cell Frameworks Retaining Strong Auxeticity under Large Uniaxial Loading

Orthotropic Laminated Open-cell Frameworks Retaining Strong Auxeticity under Large Uniaxial Loading

Interpolation of Turbulent Boundary Layer Profiles Measured in Flight Using Response Surface Methodology

Evaluation of Skin Friction Drag Reduction in Turbulent Boundary Layer Using Riblets

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