Overview of Unsteady Aerodynamic Response of Rigid Wings in Gust Encounters

Jones, Anya R.; Çeti̇ner, Okşan

doi:10.2514/1.j059602

Cited by 20 publications

(7 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the sake of completeness, note that the wing's gust response is also important in aircraft design and certification [69]. In particular, a "frozen" approach [70,71] is typically adopted for lower-fidelity analytical models [49,72] (where the aerofoil's presence is assumed not to affect the wind gust [15]), which relate Kussners's function for the indicial lift from a unit sharp-edge gust to the indicial circulation relative to Wagner's function [73,74]; an arbitrary gust can then be considered by exploiting Duhamel's convolution with Kussners's indicial-admittance function directly [75]. Later numerical studies [76] and higher-fidelity simulations [77] confirmed that quasi-steady aerodynamics is not appropriate for calculating gust responses unless the wind gust is very smooth and its length is much longer than the aerofoil's chord [75].…”

Section: Exact Solution For Unsteady Flowmentioning

confidence: 99%

On Aerodynamic Models for Flutter Analysis: A Systematic Overview and Comparative Assessment

Berci¹

2021

Applied Mechanics

View full text Add to dashboard Cite

This work reviews different analytical formulations for the time-dependent aerodynamic load of a thin aerofoil and clarifies numerical flutter results available in the literature for the typical section of a flexible wing; inviscid, two-dimensional, incompressible, potential flow is considered in all test cases. The latter are investigated using the exact theory for small airflow perturbations, which involves both circulatory and non-circulatory effects of different nature, complemented by the p-k flutter analysis. Starting from unsteady aerodynamics and ending with steady aerodynamics, quasi-unsteady and quasi-steady aerodynamic models are systematically derived by successive simplifications within a unified approach. The influence of the aerodynamic approximations on the aeroelastic stability boundary is then rigorously assessed from both physical and mathematical perspectives. All aerodynamic models are critically discussed and compared in the light of the numerical results as well, within a comprehensive theoretical framework in practice. In all cases, results accuracy depends on the aero-structural arrangement of the flexible wing; however, simplified unsteady and simplified quasi-unsteady aerodynamic approximations are suggested for robust flutter analysis whenever the wing’s elastic axis lies ahead of the aerofoil’s control point.

show abstract

Section: Exact Solution For Unsteady Flowmentioning

confidence: 99%

On Aerodynamic Models for Flutter Analysis: A Systematic Overview and Comparative Assessment

Berci¹

2021

Applied Mechanics

View full text Add to dashboard Cite

show abstract

“…where the complex function C E (k) embeds a further travelled semichord delay [93,135]. It is worth stressing that these fundamental indicial-admittance functions are also still the subject of recent studies and generalisations [185][186][187][188][189][190][191][192][193][194][195][196][197][198][199][200][201][202][203] due to their essential clarity, as powerful aerodynamic tools for thin wings in unsteady subsonic flow [204][205][206].…”

Section: Appendix Bmentioning

confidence: 99%

On the Incipient Indicial Lift of Thin Wings in Subsonic Flow: Acoustic Wave Theory with Unsteady Three-Dimensional Effects

Berci¹

2022

Acoustics

View full text Add to dashboard Cite

Enhanced approximate expressions for the incipient indicial lift of thin wings in subsonic potential flow are presented in this study, featuring explicit analytical corrections for the unsteady downwash. Lifting-line and acoustic-wave theories form the basis of the method, within an effective synthesis of the governing physics, which grants a consistent generalised framework and unifies previous works. The unsteady flow perturbation consists of a step-change in angle of attack or a vertical sharp-edged gust. The proposed model is successfully evaluated against numerical results in the literature for the initial airload development of elliptical and rectangular wings with a symmetric aerofoil, considering several aspect ratios and Mach numbers. While nonlinear downwash and compressibility terms demonstrate marginal (especially for the case of a travelling gust), both linear and nonlinear geometrical effects from a significant taper ratio, sweep angle or curved leading-edge are found to be more important than linear downwash corrections (which are crucial for the circulation growth at later times instead, along with linear compressibility corrections). The present formulae may then be used as a rigorous reduced-order model for validating higher-fidelity tools and complex simulations in industrial practice, as well as for estimating parametric sensitivities of unsteady aerodynamic loads within the preliminary design of aircraft wings in the subsonic regime.

show abstract

“…The aerodynamics of wings at low Reynolds number holds significant interest due to its relevance in various engineering applications for civil and military use such as the surveying and surveillance using RPVs (remotely piolted vehicles), MAVs (micro air vehicles), vehicles mimicking insect flights and perching birds, to name a few. The aerodynamic response of wings at low Reynolds numbers is sensitive to multiple factors such as the geometry, distribution of thickness and camber, taper and aspect ratio [1][2][3][4]. Slightest disturbances in the freestream conditions lead to large changes in the aerodynamic response.…”

Section: Introductionmentioning

confidence: 99%

On the secondary stall of a wing in tandem configuration

Shah,

Ahmed

2024

Aeronaut. j.

View full text Add to dashboard Cite

The aerodynamic response of a NACA0012 wing section was investigated at a Reynolds number of 100,000 in an open return wind tunnel in the presence of a second wing in tandem. The angle-of-attack of the front wing ranged from −5° to 90° while the rear wing remained at zero incidence. The presence of the downstream wing significantly altered the post-stall behaviour of the upstream wing in the form of a secondary stall characterised by a sudden drop in lift and drag for a specific combination of angle-of-attack and the spacing between the wings. The secondary stall was found to be insensitive to the Reynolds number and the aspect ratio of the downstream wing and did not affect the lift-to-drag ratio. Flow visualisation in the water tunnel indicated that the downstream wing effectively suppressed vortex shedding and lift fluctuations of the upstream wing.

show abstract

Overview of Unsteady Aerodynamic Response of Rigid Wings in Gust Encounters

Cited by 20 publications

References 30 publications

On Aerodynamic Models for Flutter Analysis: A Systematic Overview and Comparative Assessment

On Aerodynamic Models for Flutter Analysis: A Systematic Overview and Comparative Assessment

On the Incipient Indicial Lift of Thin Wings in Subsonic Flow: Acoustic Wave Theory with Unsteady Three-Dimensional Effects

On the secondary stall of a wing in tandem configuration

Contact Info

Product

Resources

About