Minimum Induced Drag Theorems for Joined Wings, Closed Systems, and Generic Biwings: Applications

Demasi, Luciano; Monegato, Giovanni; Rizzo, Enzo; Cavallaro, Rauno; Dipace, Antonio

doi:10.1007/s10957-015-0850-5

Cited by 28 publications

(19 citation statements)

References 10 publications

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“…Nevertheless no similar correlation was found for the torsional mode natural frequency for values of aspect ratio higher than 20, for which the first torsion and second chord-bending modes start to couple. Also from this study, the flutter mechanism was observed to change from a coupling between the first torsion mode with the second flapbending mode (for the lower aspect-ratio wings, [12][13][14][15][16] to a coupling between the first torsion mode with the third flap-bending mode (for higher aspect-ratio wings, 20-28) as the wing aspect ratio increases. Therefore, although significant changes in flutter speed occur due to high wing deformations, it is not possible to conclude how those changes affect the safety margin for flight operation.…”

Section: Discussionmentioning

confidence: 78%

“…Different approaches can be applied to increase wing Aspect Ratio (AR) for conventional designs such as increasing wingspan or reducing wing chord. Also unconventional aircraft designs such as the Joined-Wing (11,39) , the Strut-Braced-Wing (10,11) , the Box-Wing (11,19) and the C-Wing (14,15,26) also have the goal of reducing the induced drag by means of increasing the wing aspect ratio.…”

Section: Introductionmentioning

confidence: 99%

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Non-linear aeroelastic response of high aspect-ratio wings in the frequency domain

et al. 2017

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A current trend in the aeronautic industry is to increase the wing aspect ratio to enhance aerodynamic efficiency by reducing the induced drag and thus reduce fuel consumption. Despite the associated benefits of a large aspect ratio, such as higher lift-to-drag ratios and range, commercial aircraft usually have a relatively low aspect ratio. This is partially explained by the fact that the wing becomes more flexible with increasing aspect ratio and thus more prone to large deflections, which can cause aeroelastic instability problems such as flutter. In this work, an aeroelastic study is conducted on a rectangular wing model of 20 m span and variable chord for a low subsonic speed condition to evaluate the differences between linear and non-linear static aeroelastic responses. Comparisons between linear and non-linear displacements, natural frequencies and flutter boundary are performed. An in-house non-linear aeroelastic framework was employed for this purpose. In this work, the influence of the aspect ratio and geometric non-linearity (highly deformed states) is assessed in terms of aeroelastic performance parameters: flutter speed and divergence speed. A nearly linear correlation of flutter speed difference (relative to linear analysis results) with vertical-tip displacement difference is observed. The flutter and divergence speeds vary substantially as the wing aspect ratio increases, and the divergence speeds always remain above the flutter speed. Furthermore, the flutter mechanism was observed to change as the wing chord is decreased.

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Section: Discussionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Non-linear aeroelastic response of high aspect-ratio wings in the frequency domain

et al. 2017

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“…C-wings have been considered a compromise between a box wing and a winglet; theoretically providing a reduction in the induced drag that approaches that of the closed box wing 14,[29][30][31] arrangement whilst additionally reducing the viscous drag penalty incurred by large wetted areas 32,33 . The C-wing and box wing have also been recognised to have the potential to replace the conventional horizontal stabiliser to provide pitch control 18,34 .…”

Section: Armentioning

confidence: 99%

Study of a C-wing configuration for passive drag and load alleviation

Skinner

Zare‐Behtash

2018

Journal of Fluids and Structures

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Non-planar wing configurations are often hypothesised as a means for improving the aerodynamic efficiency of large transport aircraft; C-wings may have the ability to exploit and unify drag reduction, aeroelasticity, and dynamics and control but their capacity to do so is ambiguous. The purpose of this work is to provide an experimental demonstration with the aim of verifying the C-wing configurations practical application. Thus, the main objective of this investigation is to

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“…As a nonplanar and closed wing system, the box wing experiences less induced drag compared to a planar wing of the same span and lift. This comes as a result of the distribution of circulation over a greater mass of air, leading to a reduction in average kinetic energy added to the flow [27], and as a result of more gradual circulation gradients, especially near the wing tips [56].…”

Section: The Box Wingmentioning

confidence: 99%

“…Such an advantage comes from being a closed wing system, which allows a constant vortex loop to be added to the circulation with minimal penalty to induced drag [27]. Indeed, this property was corroborated by Demasi et al [56], who found the optimum partitioning of total lift between the fore and aft wings, originally assumed to be equal by…”

Section: The Box Wingmentioning

confidence: 99%

Aerodynamic Shape Optimization of a Box-Wing Regional Aircraft Based on the Reynolds-Averaged Navier-Stokes Equations

Chau

2017

35th AIAA Applied Aerodynamics Conference

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The box wing is an unconventional aircraft configuration that has the potential to provide major savings in fuel consumption relative to the conventional cantilever wing. In order to further develop and evaluate this potential, high-fidelity aerodynamic shape optimization is applied to the aerodynamic design of a box wing and a cantilever wing, based on the Embraer E190 regional jet, with the latter serving as a performance baseline. The optimization framework consists of B-spline parameterization, free-form and axial deformation geometry control, an integrated mesh-movement scheme based on the theory of linear elasticity, a Newton-Krylov-Schur flow solver for the Reynolds-averaged Navier-Stokes equations, a gradient-based optimizer, and the discrete-adjoint method for gradient evaluation. Results indicate that a box-wing with a heightto-span ratio of 0.26 burns 7.61% less fuel at cruise than a conventional baseline of the same span and lift. Aerodynamic trends and trade-offs are investigated, and a weight sensitivity study is performed.ii Acknowledgements First and foremost, I would like to thank my supervisor, Professor David Zingg. I cannot thank him enough for the opportunity to work on such a state-of-the-art problem, which has proven to be challenging, but incredibly rewarding. I also have him to thank for the invaluable knowledge and experience that I have gained during these past few years. His passion for computational aerodynamics and environmentally-friendly aircraft design is something to be envied, and will always serve as a pillar of inspiration. I would also like to thank the UTIAS community for creating a welcoming and fun work environment. To the computational aerodynamics group, thank you for all of the helpful feedback you have given me over the years, and for making my late nights in the lab palatable. In particular, I would like to thank Dr. Shahriar Khosravi for the many interesting discussions on aerodynamics and structures, and Dr. Thomas Reist for his invaluable technical guidance and discussions on aircraft design.

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Minimum Induced Drag Theorems for Joined Wings, Closed Systems, and Generic Biwings: Applications

Cited by 28 publications

References 10 publications

Non-linear aeroelastic response of high aspect-ratio wings in the frequency domain

Non-linear aeroelastic response of high aspect-ratio wings in the frequency domain

Study of a C-wing configuration for passive drag and load alleviation

Aerodynamic Shape Optimization of a Box-Wing Regional Aircraft Based on the Reynolds-Averaged Navier-Stokes Equations

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