Riblet Surfaces for Improvement of Efficiency of Wind Turbines

Leitl, Peter A.; Stenzel, Volkmar; Flanschger, Andreas; Kordy, Heinrich; Feichtinger, Christoph; Kowalik, Yvonne; Schreck, Stefan; Stübing, Dorothea

doi:10.2514/6.2020-0308

Cited by 12 publications

(5 citation statements)

References 2 publications

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“…Increasing a poor baseline deposition efficiency by harnessing physical mechanisms tapped by natural selection could, in principle, lead to improved water collection when it is most desperately needed. Implications of the relationship between surface morphology and inertial impaction broadly extend across biological systems which depend on fog ( 3 ) or pollen ( 47 , 48 ) capture, and engineering contexts, where impaction can be utilized for particle separation ( 49 ) or, alternatively, where surface modifications intended for aerodynamic benefit ( 50 ) can exacerbate unwanted capture such as icing ( 51 ).…”

Section: Discussionmentioning

confidence: 99%

Geometry for low-inertia aerosol capture: Lessons from fog-basking beetles

Shahrokhian,

Chan,

Feng

et al. 2024

PNAS Nexus

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Water in the form of windborne fog droplets supports life in many coastal arid regions, where natural selection has driven non-trivial physical adaptation toward its separation and collection. For two species of Namib desert beetle whose body geometry makes for a poor filter, subtle modifications in shape and texture have been previously associated with improved performance by facilitating water drainage from its collecting surface. However, little is known about the relevance of these modifications to the flow physics that underlies droplets’ impaction in the first place. We find, through coupled experiments and simulations, that such alterations can produce large relative gains in water collection by encouraging droplets to ‘slip’ toward targets at the millimetric scale, and by disrupting boundary and lubrication layers effects at the microscopic scale. Our results offer a lesson in biological fog collection, and design principles for controlling particle separation beyond the specific case of fog basking beetles.

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Section: Discussionmentioning

confidence: 99%

Geometry for low-inertia aerosol capture: Lessons from fog-basking beetles

Shahrokhian,

Chan,

Feng

et al. 2024

PNAS Nexus

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“…Nanoimprint patterning was used to replicate the reduce the friction on ceramic surfaces (see figure 2) 12,6 . For airplanes sharkskin-inspired structures are investigated 13 and for ships surfaces are investigated that reduce the adhesion of marine plants and animals, which, when attached to a ship hull, increase the fuel consumption of the ship significantly 14 . In photovoltaic applications anti-reflective moth-eye structures 15 and self-cleaning structures inspired by the surface of rose petals 16 , both made by nanoimprinting, can be of interest.…”

Section: Opportunities Sustainability Challengesmentioning

confidence: 99%

“…Other applications where nanoimprinting was used to structure functional materials include organic photovoltaics 37 , a dual damascene process 38 , riblet structures for wind turbines 13 , anti-fouling structures for ships 14 , microfluidics 39 , waveguides 40 , and many more.…”

Section: Other Examples From Literaturesmentioning

confidence: 99%

Direct patterning of functional materials using nanoimprint lithography

Haslinger,

Kopp,

Jonaityte

et al. 2023

38th European Mask and Lithography Conference (EMLC 2023)

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“…But how well do current engineered or fabricated materials match the characteristics of shark skin? Fabric designed for competition swimsuits has achieved some notoriety by increasing the speed of swimmers (Takagi and Sanders, 2000;Hutchinson, 2008;Oeffner and Lauder, 2012), and shark skininspired engineered riblet surfaces have been applied to wind turbines (Chamorro et al, 2013;Sareen et al, 2014;Leitl et al, 2020), and tested for drag reduction properties (Bechert et al, 2000;Zhao et al, 2012;Ibrahim et al, 2018). Do these current applications, generally inspired by shark skin, possess quantitatively accurate three-dimensional (3D) surface characteristics that match shark skin?…”

Section: Introductionmentioning

confidence: 99%

Ridges and riblets: Shark skin surfaces versus biomimetic models

Gabler-Smith

Lauder

2022

Front. Mar. Sci.

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Shark skin has been an inspiration for biomimetic materials and structures due to its role in reducing drag and enhancing thrust, properties believed to be due to the textured surface composed of ridges on the surface of individual tooth-like scales (denticles). Attempts to replicate the hydrodynamic performance of shark skin have involved manufacturing both engineered riblets and fabrics with textured surfaces. However, there are no studies that compare the surface ornamentation of shark denticles to bioinspired materials. Using three-dimensional surface profilometry we analyzed the cross-sectional profile of the surface of shark denticles at two locations on 17 species and compared these data to values obtained from engineered structures (e.g., riblets) and competition swimsuits that are often proposed as having a comparable surface texture to shark skin. Of the variables measured, crown aspect ratio (p = 0.007), ridge height, ridge spacing, ridge aspect ratio, and ridge bumpiness (all p < 0.001) differed among the three materials. Overall, engineered riblet surfaces were very different than biological shark skin. Some of the competition swimsuit materials were more shark-like, with the fabric texture having similar height variation, but with irregular ridge spacing. Cross-sectional profile, which includes pathlength and aspect ratio in addition to ridge spacing and height, is an important feature of the skin’s surface, affecting water flow over the individual denticles, and future research will address these parameters. Quantitative 3D analysis of the surface of real shark denticle ridges enables the design of more biomimetic engineered shark skin surfaces.

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Riblet Surfaces for Improvement of Efficiency of Wind Turbines

Cited by 12 publications

References 2 publications

Geometry for low-inertia aerosol capture: Lessons from fog-basking beetles

Geometry for low-inertia aerosol capture: Lessons from fog-basking beetles

Direct patterning of functional materials using nanoimprint lithography

Ridges and riblets: Shark skin surfaces versus biomimetic models

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