Aerodynamic analysis of bionic winglet- slotted wings

Dutta, Prantik; Nagar, Om P.; Sahu, Sagar; Savale, Rushikesh R.; Raj, Ritu

doi:10.1016/j.matpr.2022.04.752

Cited by 4 publications

(1 citation statement)

References 18 publications

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“…So, the reduction in friction is an omnipresent topic of research. In particular, nature demonstrates perfectly shaped surfaces, such as shark and fish skins [2] and bird wings [3], for drag reduction. Many researchers have tried to transfer these bio-inspired surfaces to technical applications and add additional indentations, called texture, to the surface, which should improve the tribological performance.…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Numerical Study of a Wedge-Shaped Textured Convergent Oil Film Gap

Scharf,

Maier,

Pusterhofer

et al. 2024

Lubricants

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The modification of surface geometries to reduce friction is an omnipresent topic of research. In nature, different low-friction surfaces, such as fish skins, exist. To transfer this knowledge to technical applications, for example, to journal or plain bearings, many numerical and experimental studies of textured surfaces have been performed. In this work, the influence of the geometric parameters (texture length , width , angle and start position of a wedge-shaped texture on three different convergent oil film gaps was analyzed in full-film lubrication and compared with untextured oil film gaps. With the aid of a CFD (computational fluid dynamics) model, a comprehensive variation study was conducted, and the best-performing wedge-shaped texture was determined. The results show that an open texture at the inlet provides the largest improvement. Furthermore, it can be observed that the optimal relative texture width and absolute inlet height for the three investigated oil film gaps are similar. In contrast to the volume flow of the untextured geometry, the volume flow of the textured one is significantly higher, especially that perpendicular to the movement direction.

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Section: Introductionmentioning

confidence: 99%

A Comprehensive Numerical Study of a Wedge-Shaped Textured Convergent Oil Film Gap

Scharf,

Maier,

Pusterhofer

et al. 2024

Lubricants

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Numerical investigation of non-planarity and relative motion for bionic slotted wings

Liu,

Cheng,

Song

et al. 2023

AIP Advances

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Bird wings have split primary feathers that extend out from the wing surface. This structure is called the wingtip slot, which is recognized as a product of bird evolution to improve flight performance. In this paper, numerical simulations based on RANS (Reynolds-averaged Navier–Stokes) equations are conducted to examine and understand the influence of wingtip slots on six wings at Re = 100 000. The overlapping grid method, driven by an in-house UDF (User Defined Function), is used to model the motion of the bionic slotted wings. The motion law of the winglets is improved based on the law extracted from a level-flying bald eagle. Then the aerodynamic force, pressure distribution, vorticity contours, wake stream, and other flow structures of the slotted wings with different layouts were compared and analyzed. The results show a significant increase in aerodynamic force when the slotted wingtips are employed. The maximum lift-to-drag ratio is also improved in our designed wing model with a non-planar wingtip by a maximum of 34% from the base wing. Each winglet works as a single wing due to the existence of slots, with a chordwise pressure distribution similar to that of the main wing. The vortex structures of slotted wings show expressive changes in the tip vortex as compared with the base wing. Additionally, an innovative bionic slotted wing is proposed with a dynamic wingtip that forms varying gaps between winglets. Due to the collective mechanism of aerodynamic interaction among multiple winglets for the innovative wing, it acquires the optimal time-averaged force during a flapping period. As expected, the slotted wingtip reduces the main wingtip vortex intensity and creates weaker vortices. The non-planarity and relative motion of the wingtip strengthen its weakening effect on the wingtip vortex and wake.

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Effect of biomimetic fish scale structure on the drag reduction performance of Clark-Y hydrofoil

Yan,

Xie,

Wang

et al. 2024

Proceedings of the Institution of Mechanical Engineers, Part M:

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A hydrofoil is a basic shape of fluid machinery blades, and its drag reduction performance is an important reference index in the field of fluid transportation. When fluid flows around a hydrofoil, it generates friction drag and pressure drag, greatly reducing the hydrofoil’s hydraulic performance. This study designs a bionic drag reduction structure by arranging fish scales on a Clark-Y hydrofoil. The overlapping size, thickness, and coverage area of fish scales are taken as design parameters, and the optimal design scheme is attained by using the Taguchi method. Large eddy simulation is used to numerically simulate various schemes. Results show that when the overlapping size O is 2.00 mm, the thickness h is 0.36 mm, the initial position x/C of the fish scale covering is 0 (where C is the chord length of the hydrofoil), and the hydrofoil exhibits excellent drag reduction performance. The total drag reduction rate of the hydrofoil is up to 35.15%, and the drag reduction rate of friction drag and pressure drag is up to 39.56% and 25.64%, respectively. The lift–drag ratio of the hydrofoil increases by 18.04%. The bionic fish scale structure effectively inhibits turbulence, thereby reducing the drag caused by the transformation of laminar flow to turbulence.

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Aerodynamic analysis of bionic winglet- slotted wings

Cited by 4 publications

References 18 publications

A Comprehensive Numerical Study of a Wedge-Shaped Textured Convergent Oil Film Gap

A Comprehensive Numerical Study of a Wedge-Shaped Textured Convergent Oil Film Gap

Numerical investigation of non-planarity and relative motion for bionic slotted wings

Effect of biomimetic fish scale structure on the drag reduction performance of Clark-Y hydrofoil

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