Effects of wing flexibility on aerodynamic performance of an aircraft model

Guo, Qinfeng; He, Xinhua; Wang, Zhuo; Wang, Jinjun

doi:10.1016/j.cja.2021.01.012

Cited by 21 publications

(8 citation statements)

References 29 publications

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“…In contrast, this project investigates a combination of two methods using an active folding of the wing and a passive adaptation of the wing surface, as in natural flyers, to enhance the flight envelope of small aircraft. The investigated morphing wing is part of a common research project with the Beihang University (He et al, 2019;Guo et al, 2021). Both project partners investigate morphing W/T models in their facilities.…”

Section: Figurementioning

confidence: 99%

“…A first feature is the superior stall characteristics, because the shape of the airfoil passively adapts to the inflow at high angles of attack. Guo et al revealed a delayed stall and an increased lift for a W/T model with flexible membrane wings (Guo et al, 2021). Furthermore, small and lightweight vehicles like micro air vehicles are exposed to a turbulent flight environment, where flexible wing surfaces can reduce loads and improve the stability (Jenkins et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Efficacy of an elasto-flexible morphing wing at high lift using fluid-structure-interaction simulations

Pflüger

Langsdorff

Breitsamter

2022

Front. Aerosp. Eng.

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The wide field of applications is the driving force behind the scientific interest in unmanned and micro air vehicles. For these aircraft, morphing wing technologies offer the possibility to adapt the aerodynamics to different flight stages. A morphing wing configuration with two elasto-flexible membrane wings is investigated numerically at a low Reynolds number of Re = 264000. The concept enables wing folding over a wide range and it allows the wing to adapt to changing aerodynamic loads. The focus is set on the benefits of the membrane in the high lift regime. Therefore, fluid-structure-interaction simulations are performed for the model equipped with a flexible and with a rigid wing. The comparison of the numerical results to data from previous experimental measurements show a good agreement. Compared with the rigid wing, the elasto-flexible membrane increases the gradient in the linear region and the maximum lift coefficient. In addition, the maximum lift coefficient is shifted to higher angles of attack. For selected wing positions and angles of attack, the aerodynamic behavior of the flexible and the rigid wing are investigated by means of the lift coefficient, the deformation of the membrane, the wall shear stresses and the wing surface pressure distribution. The deformation of the wing surface directly influences the area of flow separation at the extended wing and the separating leading-edge vortex at the folded wing. Both effects increase the generated lift of the wing with a flexible membrane.

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Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficacy of an elasto-flexible morphing wing at high lift using fluid-structure-interaction simulations

Pflüger

Langsdorff

Breitsamter

2022

Front. Aerosp. Eng.

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“…(2020) and Guo et al. (2021) all found that the lift-enhancement effect of passive flexible wings became worse at high Re . The numerical simulations of Arif et al.…”

Section: Introductionmentioning

confidence: 97%

“…When α is small, the disordered vibration may be detrimental for the aerodynamics compared with rigid cambered wings (Serrano-Galiano et al 2018). For the complex wings with partially flexible surfaces, Açıkel & Genç (2018), Genç et al (2020) and Guo et al (2021) all found that the lift-enhancement effect of passive flexible wings became worse at high Re. The numerical simulations of Arif et al (2020) and Arif, Lam & Leung (2022) on the passive control of a NACA 0012 airfoil with localized elastic panels flush mounted on the suction surface also reported that the elastic panel configuration has no significant influence on airfoil aerodynamic performance.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamics and fluid–structure interaction of an airfoil with actively controlled flexible leeward surface

Guo

et al. 2023

J. Fluid Mech.

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Piezoelectric macro-fibre composite (MFC) actuators are employed onto the flexible leeward surface of an airfoil for active control. Time-resolved aerodynamic forces, membrane deformations and flow fields are synchronously measured at low Reynolds number (Re = 6 × 104). Mean aerodynamics show that the actively controlled airfoil can achieve lift-enhancement and drag-reduction simultaneously in the angle of attack range of 10° ≤ α ≤ 14°, where the rigid airfoil encounters stall. The maximum increments of lift and lift-to-drag ratio are 27.1 % and 126 % at the reduced actuation frequency of ${f^ + } = 3.52$ . The unsteady coupling features are further analysed at α = 12°, where the maximum lift-enhancement occurs. It is newly discovered that the membrane vibrations and flow fields are locked into half of the actuation frequency when ${f^ + } > 3$ . The shift of the dominant vibration mode from bending to inclining is the reason for the novel ‘half-frequency lock-in’ phenomenon. To the fluid–structure interaction, there are three characteristic frequencies for the actively controlled airfoil: $S{t_1} = 0.5{f^ + }$ , $S{t_2} = {f^ + }$ , and $S{t_3} = 1.5{f^ + }$ . Here, St1 and its harmonics (St2, St3) are coupled with the natural frequencies of the leading-edge shear layer, resulting in the generation of multi-scale flow structures and suppression of flow separation. The lift presents comparable dominant frequencies between St1 and St3, which means the instantaneous lift is determined by the flow structures of St1 and St3. The local membrane bulge and dent affect the instantaneous swirl strength of flow structures near the maximum vibration amplitude location, which is the main reason for the variation of instantaneous lift.

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“…The research indicates that the membrane airfoil can automatically adjust the inflow by changing the radian to balance the pressure difference between the upper and lower regions, inhibit the air flow separation on the upper surface, and delay the stall of the airfoil. Guo et al [21] conducted wind tunnel experiments on a simplified aircraft model equipped with flexible membrane wings. The research indicates that under optimal conditions, the membrane wing achieves a stall delay of 5 • compared with the rigid wing, which is closely related to the flow coupling caused by membrane deformation and vibration.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on the Performance of Double Membrane Wing for Long-Endurance Low-Speed Aircraft

Zhang

Yang

et al. 2022

Applied Sciences

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Flexible membrane structure is generally used as wing skin for long-endurance low-speed aircraft, such as solar aircraft, to control the structure weight within the allowable range. Predictably, the elastic deformation of the membrane under complex loads will cause uncertain impacts on the aerodynamic performance. The existing research indicates that the deformation of the membrane wing is helpful to improve the aerodynamic characteristics. However, most of the research objects are non-thickness membrane wings. In this paper, wind tunnel experiments are performed on double membrane wings. The experiment results indicate that the membrane deformation behavior is related to the surface curvature distribution and will change the camber and thickness of the airfoil. The deformation has little effect on lift but has a significant effect on drag and pitching moment. On this basis, a high-precision fluid structure coupling analysis method for the wider range of research is introduced. The numerical analysis indicates that the deformation can delay the stall angle by 1°. Furthermore, based on the numerical results, suggestions on prestress setting during membrane skin laying are provided, and the numerical simulation results of two flexible skin wings are compared. The research results of this paper provide a scientific basis for the aerodynamic design and analysis of long-endurance low-speed aircraft.

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Effects of wing flexibility on aerodynamic performance of an aircraft model

Cited by 21 publications

References 29 publications

Efficacy of an elasto-flexible morphing wing at high lift using fluid-structure-interaction simulations

Efficacy of an elasto-flexible morphing wing at high lift using fluid-structure-interaction simulations

Aerodynamics and fluid–structure interaction of an airfoil with actively controlled flexible leeward surface

Experimental and Numerical Study on the Performance of Double Membrane Wing for Long-Endurance Low-Speed Aircraft

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