High fidelity computational simulation of a membrane wing airfoil

Gordnier, Raymond E.

doi:10.1016/j.jfluidstructs.2009.03.004

Cited by 126 publications

(22 citation statements)

References 32 publications

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“…At stall angles of α 25 deg, the structural response gets more energized, and the dominant frequency drops back to St 0.7. Low-frequency vortex shedding excites the membrane structure at low mode shapes and results in energy content for low frequencies [13]. The lower AR 1 wing (Fig.…”

Section: Results: Aerodynamic Performancementioning

confidence: 95%

“…Rigid wings show aerodynamic benefits within a camber range of 3 to 4% [10,11]. For larger camber values, flexible membrane wings offer larger benefits than similar shaped rigid cambered wings due to their inherent shape adaptability [12,13]. Flexible membrane wings interact with the shear layer, energizing it and causing it to remain close to the wing surface [12].…”

Section: Armentioning

confidence: 99%

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Aspect-Ratio Effects on Aeromechanics of Membrane Wings at Moderate Reynolds Numbers

2015

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The aspect ratio of a membrane wing at moderate Reynolds number Re 67;500 affects aerodynamic performance as well as membrane deformations. Wind-tunnel experiments are conducted using three different lowaspect-ratio wings (aspect ratios of 1, 1.5, and 2). Aerodynamic performance is determined from force and moment measurements, which are performed using a six-component force transducer. Membrane deformations are obtained using photogrammetry. Mean values and unsteady effects are examined for both aerodynamic performance and membrane deformations. Mean deflection results indicate that lower-aspect-ratio membrane wings show defined Ushape deflections along the span, whereas higher aspect ratios display a progressive rise in deformation to the wing tip. Dominant chordwise vibration modes of the membrane and their spectral content show that lower aspect ratios exhibit higher mode shapes and frequencies, likely caused by increased downwash, which delays the influence of vortex shedding into higher incidences. The frequencies of the dominant modes in membrane motions are found to correlate with the frequencies of lift and drag fluctuations.Reynolds number S = half-wing area St = fc∕U ∞ , Strouhal number x = streamwise coordinate y = spanwise coordinate z = camberwise coordinate α = global angle of attack, deg Π = Et∕qc 1∕3 , aeroelastic parameter σ = standard deviation

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Section: Results: Aerodynamic Performancementioning

confidence: 95%

Section: Armentioning

confidence: 99%

Aspect-Ratio Effects on Aeromechanics of Membrane Wings at Moderate Reynolds Numbers

2015

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“…The static deformation affects the airfoil camber and tip wash-out advantageously by altering the aerodynamic and geometric twist distribution on the wing [18][19][20][21]. The dynamic deformation, or membrane vibration, interacts with the separated shear layer, increasing the momentum transfer and reducing the flow separation [21,22]. Because advantageous properties of the membrane wing appear to be related to both static and dynamic deformation, research interest in the interaction of membrane dynamics and unsteady flow structure surrounding the wing has recently intensified.…”

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confidence: 99%

Geometry and Prestrain Effects on the Aerodynamic Characteristics of Batten-Reinforced Membrane Wings

Zheng

Martin

Wrist

et al. 2016

Journal of Aircraft

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To lessen the deterioration of fixed-wing aerodynamic performance associated with chord Reynolds numbers below 100,000, flexible membrane wing designs have been studied and proposed as an alternative for micro air vehicle use. The beneficial effects of a flexible membrane can include higher lift, steeper lift-curve slope, delayed stall, gentle stall characteristics, and greater efficiency. These benefits have been attributed to both the time-averaged and dynamic deformation of the membrane. This work discusses the geometric and prestrain effects on a battenreinforced, free trailing-edge membrane wing in low-Reynolds-number (50,000) flow. The global aerodynamic forces on the wings with varying wing aspect ratio, cell aspect ratio, and prestrain level were measured. The results show that the aerodynamic advantages of the flexible membrane are retained for the low-aspect-ratio wings. The optimal membrane cell aspect ratio is found to be approximately 1. The comparison of the aerodynamic forces between the low-aspect-ratio membrane wings and the corresponding three-dimensional-printed wings with the time-averaged deformation indicates the importance of membrane dynamic motion for the derived aerodynamic benefits.

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“…Greater the velocity smaller will be the value of the aeroelastic parameter. Flexibility creates oscillation and when Reynolds number increases, aeroelastic parameter will decrease which will shift the shear layer close to wing surface while the camber will increase (Gordnier, 2009). value of thickness which is 0.4mm & 1mm respectively.…”

Section: Effect Of Flexibilitymentioning

confidence: 99%

“…Rigid tips behaviour Graph between L/D vs angle of attack At a fixed value of aeroelastic parameter, significant decrease in the size of the separation zone is seen (Gordnier, 2009). For flexible curved tip, the value of aeroelastic parameter is around 148.2 while it is 201.1 for flexible flat tip.…”

mentioning

confidence: 98%