Flow Field Analysis and Contour Detection of a Natural Owl Wing Using PIV Measurements

Winzen, Andrea; Klän, Stephan; Klaas, Michael; Schröder, Wolfgang

doi:10.1007/978-3-642-28302-4_7

Cited by 8 publications

(11 citation statements)

References 12 publications

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“…This result supports the statement [20,21] that the properties of the owlwings increase aerodynamic performance by increasing lift (and decreasing drag), which is necessary to fly effectively at lowflow speeds.…”

Section: Aerodynamic Resultssupporting

confidence: 89%

“…At low flows peeds, March et al state that the lift coefficient is higher since the wing is less deformed, while the deformation is significant at high speeds and high angles of attack. No such strong deformation waso bserved in the present study.Intheir PIV measurements on aprepared barn owl wing, Winzen et al [21] also observed a"straightening of the wing" with increasing flowspeed. However, the max-imum local displacement of the wing surface theym easured wasr elatively small (int he order of 1m ma tz ero angle of attack and still below4mmatanangle of attack of 6 • )f or flows peeds from 3.5 m/s to 10.5 m/s, butn o strong deformation occured.…”

Section: Aerodynamic Resultsmentioning

confidence: 88%

“…The latter wasalready done qualitatively by Kroeger et al [7] and by Neuhaus et al [9], who concluded that the leading edge comb merely serves to delay the separation of the flowatnear-stall conditions. The PIV study on ap repared wing of ab arn owlb yW inzen et al [21] wasfocused on the bending and twisting of the wing due to its elasticity,but the role of the plumage adaptations wasn ot investigated. Therefore, the application of more advanced non-intrusive measurement techniques, likePIV or Laser Doppler Anemometry (LDA), may enable abetter quantification of the aerodynamic and acoustic effects of the plumage adaptations.…”

Section: Acoustic Resultsmentioning

confidence: 99%

“…As opposed to the observations made by Kroeger et al regarding the aerodynamic performance of owls, Klän et al [20] examined an owl-based airfoil and argue that the surface structure of the owlw ing may contribute to an increase of the aerodynamic performance of the wing by decreasing or suppressing the separation bubble or by stabilizing it. More recently,W inzen et al [21] performed Particle Image Ve locimetry (PIV)m easurements on aprepared barn owlwing to study flowphenomena likes eparation, transition, and reattachment, and compared the results to those from Klän et al [20] for the artificial owl-based wing. Interestingly,a so pposed to the results obtained for the artificial wing, theydid not observe the formation of aseparation bubble at all.…”

Section: The Silent Flight Of Owlsmentioning

confidence: 98%

See 3 more Smart Citations

Silent Owl Flight: Comparative Acoustic Wind Tunnel Measurements on Prepared Wings

Geyer¹,

Sarradj²,

Fritzsche³

2013

Acta Acustica united with Acustica

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The wings and feathers of most genera of owls showu nique properties that are held responsible for the silent flight of the owls. This ability to fly silently has long been of interest for engineers, with the aim to transfer the basic noise reducing mechanisms to technical applications such as blades of fans and propellers. The present paper describes acoustic and aerodynamic wind tunnel measurements on prepared bird wings of different species, among them twosilently flying species of owls, the barn owl( Tyto alba)a nd the tawnyo wl (Strix aluco). The different wings are characterized in the study as technical airfoils in terms of their acoustic and aerodynamic performance. The experiments took place in an aeroacoustic open jet wind tunnel using microphone array measurement technique and deconvolution beamforming algorithms. Simultaneously to the acoustic measurements, the aerodynamic forces of the wings were captured using asix-component balance. This study,which is acomplementary study to the approach of performing flyoverm easurements on birds flying in gliding flight, further confirms experimentally that the silent owlflight is aconsequence of the special wing and plumage adaptations of the owls and not aconsequence of their lower flight speed only.

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Section: Aerodynamic Resultssupporting

confidence: 89%

Section: Aerodynamic Resultsmentioning

confidence: 88%

Section: Acoustic Resultsmentioning

confidence: 99%

Section: The Silent Flight Of Owlsmentioning

confidence: 98%

See 2 more Smart Citations

Silent Owl Flight: Comparative Acoustic Wind Tunnel Measurements on Prepared Wings

Geyer¹,

Sarradj²,

Fritzsche³

2013

Acta Acustica united with Acustica

View full text Add to dashboard Cite

show abstract

“…Many studies have been reported that using a serrated design on the leading edge of an aircraft wing reduces aerodynamic noise [1] [2] [3]. In addition, the barn owl Journal of Flow Control, Measurement & Visualization glides to hunt its prey at 2.5 m/s to 5.0 m/s, which corresponds with the flight Reynolds number range of 30,000 -90,000 based on the mean chord length of 180 mm [4]. The aerospace community is interested in the low-Reynolds-number flight and flapping flight for developing micro air vehicles (MAVs) [5] and Martian atmospheric flight vehicles [6] [7] whose cruise Reynolds number is in the order of Ο (10 4 ).…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Owl-Like Airfoil Aerodynamics at Low Reynolds Numbers

Anyoji¹,

Wakui²,

Hamada³

et al. 2018

JFCMV

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This study experimentally investigates aerodynamic characteristics and flow fields of a smooth owl-like airfoil without serrations and velvet structures. This biologically inspired airfoil design is intended to serve as the main-wing for low-Reynolds-number aircrafts such as micro air vehicles. Reynolds number dependency on aerodynamics is also evaluated at low Reynolds numbers. The results of the study show that the owl-like airfoil has high lift performance with a nonlinear lift increase due to the presence of a separation bubble on the suction side. A distinctive flow feature of the owl airfoil is a separation bubble on the pressure side at low angles of attack. The separation bubble switches location from the pressure side to the suction side as the angle of attack increases and is continuously present on the surface within a wide range of angles of attack. The Reynolds number dependency on the lift curves is insignificant, although differences in the drag curves are especially pronounced at high angles of attack. Eventually, we obtain the geometric feature of the owl-like airfoil to increase aerodynamic performance at low Reynolds numbers.

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Particle-image velocimetry investigation of the fluid-structure interaction mechanisms of a natural owl wing

2015

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The increasing interest in the development of small flying air vehicles has given rise to a strong need to thoroughly understand low-speed aerodynamics. The barn owl is a well-known example of a biological system that possesses a high level of adaptation to its habitat and as such can inspire future small-scale air vehicle design. The combination of the owl-specific wing geometry and plumage adaptations with the flexibility of the wing structure yields a highly complex flow field, still enabling the owl to perform stable and at the same time silent low-speed gliding flight. To investigate the effects leading to such a characteristic flight, time-resolved stereoscopic particle-image velocimetry (TR-SPIV) measurements are performed on a prepared natural owl wing in a range of angles of attack 0° ≤ α ≤ 6° and Reynolds numbers 40,000 ≤ Re(c) ≤ 120,000 based on the chord length at a position located at 30% of the halfspan from the owl's body. The flow field does not show any flow separation on the suction side, whereas flow separation is found on the pressure side for all investigated cases. The flow field on the pressure side is characterized by large-scale vortices which interact with the flexible wing structure. The good agreement of the shedding frequency of the pressure side vortices with the frequency of the trailing-edge deflection indicates that the structural deformation is induced by the flow field on the pressure side. Additionally, the reduction of the time-averaged mean wing curvature at high Reynolds numbers indicates a passive lift-control mechanism that provides constant lift in the entire flight envelope of the owl.

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Flow Field Analysis and Contour Detection of a Natural Owl Wing Using PIV Measurements

Cited by 8 publications

References 12 publications

Silent Owl Flight: Comparative Acoustic Wind Tunnel Measurements on Prepared Wings

Silent Owl Flight: Comparative Acoustic Wind Tunnel Measurements on Prepared Wings

Experimental Study of Owl-Like Airfoil Aerodynamics at Low Reynolds Numbers

Particle-image velocimetry investigation of the fluid-structure interaction mechanisms of a natural owl wing

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