Experimental analysis of the flow field over a novel owl based airfoil

Klän, Stephan; Bachmann, Thomas; Klaas, Michael; Wagner, Hermann; Schröder, Wolfgang

doi:10.1007/978-3-642-11633-9_32

Cited by 5 publications

(5 citation statements)

References 0 publications

(5 reference statements)

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“…Although these data demonstrate the noise-reducing capabilities of the velvet-like surface, recently a further function has been described. Wind tunnel studies showed reduced flow separation for artificial wings covered with artificial velvet-like surfaces (Kl€ an et al 2009;Winzen et al 2012Winzen et al , 2014a. Thus, the velvet-like surface has also an aerodynamic effect.…”

Section: Functional Aspects Of the Velvet-like Surfacementioning

confidence: 99%

“…The first six measurement positions had a distance of 0.05 in the normalized x-axis, starting at 0.05 and ending at 0.3 of the normalized x-axis. This was done because most effects of the flow field, including boundary layer separation at artificial owl-based wing models, were found in this particular region (Kl€ an et al 2009Winzen et al 2012Winzen et al , 2014a. Between 0.4 and 0.9 of the normalized x-axis, the measurement positions were set in steps of 0.1 of the x-axis.…”

Section: Selection Of Positionsmentioning

confidence: 99%

“…This is interesting because it was shown that the addition of a velvet-like surface to an artificial wing reduced flow separation and enabled boundary-layer control (Kl€ an et al 2009;Winzen et al 2012Winzen et al , 2014a. Since the aerodynamic characteristics of a wing, such as the boundary layer, Reynolds number, shear stress and pressure distribution, change in both the spanwise and chordwise directions (Usherwood et al 2005;Kl€ an et al 2009Kl€ an et al , 2012Winzen et al 2012Winzen et al , 2014aWinzen et al , 2015Winzen & Roidl, 2016), the shapes of the barbs and barbules that form the velvet-like surface may do so, too. Thus, here we tested the hypothesis that the characteristics of the velvet-like surface change along the chordwise and spanwise directions of the T. furcata pratincola wing.…”

Section: Introductionmentioning

confidence: 99%

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Distribution of the characteristics of barbs and barbules on barn owl wing feathers

Weger

Wagner

2017

J. Anat.

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Owls are known for the development of a silent flight. One conspicuous specialization of owl wings that has been implied in noise reduction and that has been demonstrated to change the aerodynamic behavior of the wing is a soft dorsal wing surface. The soft surface is a result of changes in the shape of feather barbs and barbules in owls compared with other bird species. We hypothesized that as the aerodynamic characteristics of a wing change along its chordwise and spanwise direction, so may the shape of the barbs and barbules. Therefore, we examined in detail the shapes of the barbs and barbules in chordwise and spanwise directions. The results showed changes in the shapes of barbs and barbules at the anterior and distal parts of the wing, but not at more posterior parts. The increased density of hook radiates at the distalmost wing position could serve to stiffen that vane part that is subject to the highest forces. The change of pennulum length in the anterior part of the wing and the uniformity further back could mean that a soft surface may be especially important in regions where flow separation may occur.

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Section: Functional Aspects Of the Velvet-like Surfacementioning

confidence: 99%

Section: Selection Of Positionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Distribution of the characteristics of barbs and barbules on barn owl wing feathers

Weger

Wagner

2017

J. Anat.

Self Cite

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“…Consequently, aeroacoustic noise above 2 kHz can be effectively attenuated by the compliant surface covered by the down feathers through a bypass dissipation mechanism [10,11]. In the last decade, the use of an owl-wing-inspired trailing edge design as a passive control approach for an airfoil model to minimize drag and improve lift coefficients has gained attention [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Effect of the Extended Rigid Flapping Trailing Edge Fringe on an S833 Airfoil

Yu¹,

Yang²

2022

Applied Sciences

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A 2D numerical simulation was conducted to investigate the effect of an extended rigid trailing edge fringe with a flapping motion on the S833 airfoil and its wake flow field, as an analogy of an owl’s wing. This study aims to characterize the influence of the extended flapping fringe on the aerodynamic performance and the wake flow characteristics downstream of the airfoil. The length (Le) and flapping frequencies (fe) of the fringe are the key parameters that dominate the impact on the airfoil and the flow field, given that the oscillation angular amplitude is fixed at 5°. The simulation results demonstrated that the airfoil with an extended fringe of 10% of the chord at a flapping frequency of fe = 110 Hz showed a substantial effect on the pressure distribution on the airfoil and the flow characteristics downstream of the airfoil. An irregular vortex street was predicted downstream, thus causing attenuations of the vorticities, and shorter streamwise gaps between each pair of vortices. The extended flapping fringe at a lower frequency than the natural shedding vortex frequency can effectively break the large vortex structure up into smaller scales, thus leading to an accelerated attenuation of vorticities in the wake.

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“…For improvement of aerodynamic performance, the application of the owl wing airfoil has also generated evident results. Klan et al (2009) based on the Birnbaum-Glauert function to reconstruct and modify the scanned owl airfoil line, and arranged the velvet on the airfoil surface. Experiments results showed that the presence of velvet can reduce the formation of separation vortices.…”

Section: Introductionmentioning

confidence: 99%

Effects of Bionic Volute Tongue Bioinspired by Leading Edge of Owl Wing and Its Installation Angle on Performance of Multi-Blade Centrifugal Fan

Dong¹,

Dou²

2021

JAFM

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Effect of the volute tongue of the multi-blade centrifugal fan on the performance of the machines is significance. The shape and installation angle of the volute tongue affect the circulating internal flow behavior of the volute as well as the energy loss around the volute tongue. In this study, the profile of the leading edge of the owl wing is applied to the volute tongue of a multi-blade centrifugal fan to improve the aerodynamic performance of the fan. The fan models with different volute tongue installation angles are numerically simulated under different flow conditions. The research results show that the proposed design is able to improve the aerodynamic performance of the fan at different flow rate conditions. In addition, an improved method for quantitatively evaluating the level of impeller-volute tongue interaction based on the unsteady simulation result is proposed and it is verified to be effective. Furthermore, the two parameters for evaluating the internal flow circulation which are influenced by the installation angle of the bionic volute tongue are analyzed, namely the recirculated flow coefficient and the reversed flow coefficient. Combined with the analysis of energy loss around the volute tongue, the mechanism of variation of the aerodynamic performance of the multi-blade centrifugal fan with different volute tongue installation angles is explained.

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Experimental analysis of the flow field over a novel owl based airfoil

Cited by 5 publications

References 0 publications

Distribution of the characteristics of barbs and barbules on barn owl wing feathers

Distribution of the characteristics of barbs and barbules on barn owl wing feathers

Effect of the Extended Rigid Flapping Trailing Edge Fringe on an S833 Airfoil

Effects of Bionic Volute Tongue Bioinspired by Leading Edge of Owl Wing and Its Installation Angle on Performance of Multi-Blade Centrifugal Fan

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