Analyzing the Dynamic Behavior of a High Aspect Ratio Wing Incorporating a Folding Wingtip

Cheung, Ronald C.; Rezgui, Djamel; Cooper, Jonathan E.; Wilson, Thomas

doi:10.2514/6.2020-2290

Cited by 6 publications

(9 citation statements)

References 5 publications

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“…Using a model with the locked hinge, the distribution of both CBEAM elements and concentrated masses along the wing were optimised to closely match the modal frequencies, below 15 Hz, previously measured with the experimental model at a wind speed velocity of 18 ms −1 [17].…”

Section: A Baseline Modelmentioning

confidence: 99%

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On the Effect of Geometric Nonlinearity on the Dynamics of Flared Folding Wingtips

Healy¹,

Cheung²,

Rezgui³

et al. 2023

Journal of Aircraft

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Recent studies have considered the use of flared folding wingtips (FFWTs) to enable higher aspect ratios -reducing overall induced drag -whilst reducing gust loading and meeting airport operational requirements. The majority of these analyses have employed linear assumptions despite the presence of large wingtip deformations. In this paper the effect of geometric nonlinearities introduced by an FFWT on the static and dynamic aeroelastic response of a wing is assessed. A geometrically exact expression was formulated to describe the change in the local Angle of Attack (AoA) in the chordwise direction across all fold angles. This expression highlighted that the aerodynamic stiffness of an FFWT, and therefore quantities such as the linear flutter speed, are a function of the fold angle and hence, the attitude of the wing. This effect was verified using both: a wind tunnel model of a flexible semi-span wing, and a numerical model utilising MSC Nastran, which linearised the model about the equilibrium position of the wingtip. These experiments showed that the geometric nonlinearities introduced due to the large deformations of FFWTs can significantly affect the dynamics of the system, with flutter speeds varying by over 28%, simply by changing the AoA of the model.

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Section: A Baseline Modelmentioning

confidence: 99%

“…Whilst the wingtips of the 777X can only be operated on the ground, the inclusion of such a mechanism raises the question as to whether folding wingtips can be utilised in-flight for aerodynamic or structural benefits. One such solution is the Flared Folding Wingtip (FFWT) [8][9][10][11][12][13][14][15][16][17][18]. As illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

On the Effect of Geometric Nonlinearity on the Dynamics of Flared Folding Wingtips

Healy¹,

Cheung²,

Rezgui³

et al. 2023

Journal of Aircraft

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“…Moreover, the achieved reduction from the wind tunnel measurements is higher than predicted. Cheung et al 15,16 added an aerodynamic surface into the wingtip to control the folding action. In a series of steady aerodynamic tests, they demonstrated that this device is capable of maintaining the orientation of the wingtip over a range of wind tunnel velocities and angles of attack.…”

Section: Introductionmentioning

confidence: 99%

“…Figure16. Comparison of the shear force-torsional moment convex hull obtained with the wingtip rigidly connected to the wing and the wingtip free to rotate.…”

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confidence: 99%

The effect of folding wingtips on the worst-case gust loads of a simplified aircraft model

Balatti

Khodaparast

Friswell

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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In recent years, the development of lighter and more efficient transport aircraft has led to an increased focus on gust load alleviation. A recent strategy is based on the use of folding wingtip devices that increase the aspect ratio and therefore improve the aircraft performance. Moreover, numerical studies have suggested such a folding wingtip solution may incorporate spring devices in order to provide additional gust load alleviation ability in flight. It has been shown that wingtip mass, stiffness connection and hinge orientation are key parameters to avoid flutter and achieve load alleviation during gusts. The objective of this work is to show the effects of aeroelastic hinged wingtip on the problem of worst-case gust prediction and the parameterization and optimization of such a model for this particular problem, that is, worst-case gust load prediction. In this article, a simplified aeroelastic model of full symmetric aircraft with rigid movable wingtips is developed. The effects of hinge position, orientation and spring stiffness are considered in order to evaluate the performance of this technique for gust load alleviation. In addition, the longitudinal flight dynamics of a rigid aircraft with an elastic wing and folding wingtips is studied. Multi-objective optimizations are performed using a genetic algorithm to exploit the optimal combinations of the wingtip parameters that minimize the gust response for the whole flight envelope while keeping flutter speed within the safety margin. Two strategies to increase flutter speed based on the modification of the wingtip parameters are presented.

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“…. 9 1.7 Wing in the wind tunnel in a free-hinge configuration (directly adapted from [7] 1.9 Tethered flight test of the AlbatrossOne model (directly adapted from [8]). 14 1.10 Discrete-gust approach to design (directly adapted from [9]).…”

Section: Titlementioning

confidence: 99%

Numerical and experimental studies of aeroelastic hinged wingtips

Balatti¹

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Aeroelasticity is the science that investigates the mutual interaction between aerody-namic, elastic, and inertia forces and how this affects the static and dynamic structural response. Aeroelastic models can be defined considering different levels of fidelity de-pending on the models’ aim. Gust loads are among the most critical cases an aircraft can encounter, and so mitigating the loads enables the design of a lighter structure, consequently reducing production and fuel consumption costs. Hinged wingtips have shown potential to improve the wing aerodynamic performance while alleviating struc-tural loads. The aim of this work is the numerical and experimental study of aeroelastic wings with hinged wingtips subjected to gusts. Measurements from wind tunnel tests are used to validate the numerical model. Two numerical models, representative of the same aircraft with hinged wingtips subjected to gusts, were considered, a detailed and a simplified one. The latter model, due to its low number of degrees of freedom, was used for wingtip design optimisation. Gust and turbulence events cannot be measured di-rectly, but they can be identified from in-flight measurements. Cubic B-spline functions were used for gust identification considering simulated flight data from the simplified and detailed models. Results have shown the ability of the simplified model to identify the gust and turbulence considering simulated data from the detailed model. To validate the numerical models, a gust generator was designed, installed and commissioned for the Swansea University wind tunnel. Experimental results have shown the difficulty of creating a perfect ‘1-cos’ gust at the desired location. Two techniques to improve the ‘1-cos’ gust were considered. In the first case, the transfer function between the vane rotation and the gust produced at the aircraft model location was identified, and its in-verse was used to calculate the vane rotation. The improvements using this approach are limited by the strong nonlinearity of the aerodynamics. A parametric study of the vane rotation has shown that a more complicated vane rotation function allows ‘1-cos’ gusts at the aircraft model location to be obtained with a mean square error two orders of magnitude smaller than the initial case. An elastic wing able to accommodate different wingtips was manufactured. Three wingtips, namely a fixed wingtip, a hinged wingtip, and a hinged wingtip with a torsional spring at the hinge were considered. Static and dynamic wind tunnel tests have shown the potential of hinged wingtips in reducing wing gust loads. Measured gust loads were used to validate the aeroelastic models.

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Analyzing the Dynamic Behavior of a High Aspect Ratio Wing Incorporating a Folding Wingtip

Cited by 6 publications

References 5 publications

On the Effect of Geometric Nonlinearity on the Dynamics of Flared Folding Wingtips

On the Effect of Geometric Nonlinearity on the Dynamics of Flared Folding Wingtips

The effect of folding wingtips on the worst-case gust loads of a simplified aircraft model

Numerical and experimental studies of aeroelastic hinged wingtips

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