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A review on non-linear aeroelasticity of high aspect-ratio wings

PROGRESS IN AEROSPACE SCIENCES 2017年第Feb.期89卷 40-57页

作者： Afonso, Frederico Vale, Jose Oliveira, Eder Lau, Fernando Suleman, Afzal Univ Lisbon Inst Super Tecn IDMEC CCTAE Ave Rovisco Pais 1 P-1049001 Lisbon Portugal Univ Victoria Dept Mech Engn Victoria BC V8W 2Y2 Canada

Current economic constraints and environmental regulations call for design of more efficient aircraft configurations. An observed trend in aircraft design to reduce the lift induced drag and improve fuel consumption and emissions is to increase the wing aspect-ratio. However, a slender wing is more flexible and subject to higher deflections under the same operating conditions. This effect may lead to changes in dynamic behaviour and in aeroelastic response, potentially resulting in instabilities. Therefore, it is important to take into account geometric non-linearities in the design of high aspect-ratio wings, as well as having accurate computational codes that couple the aerodynamic and structural models in the presence of non-linearities. Here, a review on the state-of-the-art on non-linear aeroelasticity of high aspect-ratio wings is presented. The methodologies employed to analyse high aspect-ratio wings are presented and their applications discussed. Important observations from the state-of-the-art studies are drawn and the current challenges in the field are identified.

关键词： non-linear aeroelasticity High aspect-ratio wings Flexible structures Geometric non-linearities Computational aeroelasticity

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non-linear aeroelasticity: An approach to compute the response of three-blade large-scale horizontal-axis wind turbines

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RENEWABLE ENERGY 2014年 66卷 495-514页

作者： Gebhardt, C. G. Roccia, B. A. Fraunhofer Inst Wind Energy & Energy Syst Technol Bremerhaven Germany Natl Univ Rio Cuarto Cordoba Argentina Natl Sci & Tech Res Council Buenos Aires DF Argentina Natl Univ Cordoba Cordoba Argentina

In this work, we present an aeroelastic model intended for three-blade large-scale horizontal-axis wind turbines. This model results from the coupling of an existing aerodynamic model and a structural model based on a segregated formulation derived in an index-based notation that enables combining very different descriptions such as rigid-body dynamics, assumed-modes techniques and finite element methods. The developed structural model comprises a supporting tower, a nacelle, which contains the electrical generator, power electronics and control systems, a hub in which the blades are connected to a rotating shaft, and three blades, which extract energy from the wind. Flexible blades are discretized into beam finite elements and the flexible tower is discretized into assumed modes. The nacelle and hub are considered rigid. To illustrate the flexibility of the structural modeling, the tower, nacelle and hub are modeled as a single kinematic chain and each blade is modeled separately. To establish the blade-hub attachments, we use constraint equations. Thus, the resulting equations are differential algebraic. We also expose a general procedure for connecting the non-matching structural and aerodynamic meshes. Finally, we present results, some of them are validations, which prove that our new approach is reliable and does have capability to capture non-linear phenomena such as centrifugal stiffening, flutter and large yaw errors, and the remaining ones correspond to the aeroelastic response of a wind turbine during a start-up maneuvering. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Three-blade large-scale horizontal-axis wind turbines Segregated structural formulation non-linear-unsteady vortex-lattice method Inter-model combination non-linear aeroelasticity

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Optimization and comparison of strut-braced and high aspect ratio wing aircraft configurations including flutter analysis with geometric non-linearities

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AEROSPACE SCIENCE AND TECHNOLOGY 2022年第0期124卷

作者： Sohst, Martin do Vale, Jose Lobo Afonso, Frederico Suleman, Afzal Univ Victoria Dept Mech Engn Victoria BC V8P 5C2 Canada Univ Lisbon Inst Super Tecn IDMEC Av Rovisco Pais 1 P-1049001 Lisbon Portugal

Novel aircraft designs employing wings with high aspect ratio, such as the strut-braced wing (SBW), are one way to reduce their environmental impact. However, the flexibility of longer and more slender wings leads to higher deformations in cruise flight and off-design conditions. Therefore, the interdependence between aerodynamics and structure should be assessed in a multi-disciplinary design optimization (MDO) framework. Although MDO is computationally expensive, it can be mitigated by the use of surrogate models and efficient global optimization methods. This work aims to optimize a SBW aircraft using surrogate models considering flexibility effects. Another objective is to compare the resulting SBW aircraft with a similarly optimized conventional high aspect ratio wing (HARW) aircraft. Both optimized designs are compared regarding their potential fuel consumption and mass benefits under structural and aeroelastic constraints. Despite slightly heavier, the SBW design was found to improve the aerodynamic efficiency compared to an equally optimized HARW configuration. Further, non-linear aeroelastic analyses using multi-fidelity tools were carried out to assess if geometric non-linearities affect the optimized designs. These, while expensive to assess, offer further optimization potential for complex structures. (c) 2022 Elsevier Masson SAS. All rights reserved.

关键词： Novel aircraft design Strut-braced wing MDO Surrogate-based optimization non-linear aeroelasticity

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non-linear aeroelastic analysis in the time domain of high-aspect-ratio wings: Effect of chord and taper-ratio variation

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AERONAUTICAL JOURNAL 2017年第1235期121卷 21-53页

作者： Suleman, A. Afonso, F. Vale, J. Oliveira, E. Lau, F. Univ Victoria Mech Engn Dept Victoria BC Canada Univ Lisbon Inst Super Tecn IDMEC CCTAE Lisbon Portugal

Commercial jets usually have relatively low-aspect-ratio wings, in spite of the associated benefits of increasing the wing aspect-ratio, such as higher lift-to-drag ratios and ranges. This is partially explained by the fact that the wing becomes more flexible by increasing the aspect-ratio that results in higher deflections which can cause aeroelastic instability problems such as flutter. An aeroelastic computational framework capable of evaluating the effects of geometric non-linearities on the aeroelastic performance of high-aspect-ratio wings has been developed and validated using numerical and experimental data. In this work, the aeroelastic performance of a base wing model with 20 m span and 1 m chord is analysed and the effect of changing the wing chord or the taper-ratio is determined. The non-linear static aeroelastic equilibrium solutions are compared in terms of drag polar, root bending moment and natural frequencies, and the change in the flutter speed boundary is assessed as a function of aspect ratio using a time-marching approach.

关键词： aeroelasticity aircraft design non-linear aeroelasticity high-aspect-ratio wing chord and taper-ratio variation

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Unsteady and non-linear aeroelastic analysis of large horizontal-axis wind turbines

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2014年第16期39卷 8813-8820页

作者： Maza, Mauro S. Preidikman, Sergio Flores, Fernando G. Consejo Nacl Invest Cient & Tecn RA-1033 Buenos Aires DF Argentina Univ Nacl Cordoba F C E F & N Dept Estruct RA-5000 Cordoba Argentina

Analysis results, obtained from numerical simulation, for non-linear and unsteady aeroelastic behavior of large horizontal-axis wind turbines are presented in this paper. Simulations are carried out using a partitioned scheme of weak interaction that allows dealing with the fluid structure interaction problem by using one method to solve the structural-dynamic problem and another method for the aerodynamic problem. The aerodynamic model used is the non-linear, unsteady vortex lattice method (NLUVLM). The structural model used is a system of beam finite elements and rigid bodies with finite rotation. This provides a very general tool with relatively low computational cost. The proposed method allows predicting from the operating conditions (wind speed and direction, pitch angle of blades, etc.) the aeroelastic response of wind turbines, characterized by variables such as rotation speed of the rotor, loads on the structural components and the extracted power, among others. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Computational aeroelasticity non-linear aeroelasticity Unsteady aeroelasticity Fluid-structure interaction

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A non-linear theory of torsional divergence

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2009年第11期223卷 2707-2711页

作者： Campanile, L. F. Thwapiah, G. EMPA Swiss Fed Labs Mat Testing & Res CH-8600 Dubendorf Switzerland ETH Ctr Struct Technol Zurich Switzerland

In recent years, research on aerofoil morphing is increasingly focusing Oil innovative ideas such as the Use of compliant systems and the exploitation of aeroelastic servo-effects. If brought to their limit, these concepts would allow operating aerofoils in aeroelastically marginally stable or even Unstable conditions. In this view, a non-linear approach to aeroelastic torsional divergence becomes relevant. This article presents an extension of the well-known linear theory of divergence, which takes into account non-linear effects of structural as well as aerodynamic nature. The non-linear theory is applied to the case of a thin aerofoil and the pre-critical as well as post-critical response is computed for selected values of the flow parameters. Instability curves are also included, which show the aerofoil's torsional deformation as a function of the dynamic pressure, for selected values of an imposed disturbance.

关键词： non-linear aeroelasticity morphing wings compliant systems active aeroelasticity torsional divergence

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non-linear aeroelastic investigations of store(s)-induced limit cycle oscillations

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING 2008年第G1期222卷 63-80页

作者： Abbas, L. K. Chen, Q. Marzocca, P. Milanese, A. Clarkson Univ Dept Mech & Aeronaut Engn Potsdam NY 13699 USA Nanjing Univ Aeronaut & Astronaut Coll Aerosp Engn Jiangsu Peoples R China

In the current work, the study of the aeroelastic behaviour of a wing with external store(s), such as a missile or drop fuel tank, is presented. The aeroelastic governing equations derived for a cantilever wing with coupled bending and torsion modes account for structural and aerodynamic non-linearities. Coupling terms retained in the aeroelastic governing equations are due to: (a) the non-linear beam theory, (b) the aerodynamic non-linearities of a quasi-steady model with stall, and (c) the non-linear kinematics terms of the store(s). As presented in the paper, this aircraft configuration can induce pathologies, such as store (s) -induced limit cycle oscillations (or si-LCOs), very different from the one of a clean wing configuration, and from the one obtained from the linearized form of the aeroelastic governing equations. Time domain simulation, phase portrait, and bifurcation analyses are performed for various velocities, initial conditions, and store(s)-sensitive parameters - such as store mass, number, location along the wing - to examine the dynamic aeroelastic instabilities of the system (e.g. the onset of flutter and LCO). Numerical studies indicate the presence of regions of subcritical Hopf-bifurcation, corresponding to an unstable LCO, for velocities below the linear flutter velocity.

关键词： non-linear aeroelasticity multiple store(s) flutter limit cycle oscillations

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Modèle aéroélastique appliqué à la déformation d'un gréement

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Revue Européenne de Génie Civil 2008年第5期12卷 549-560页

ABSTRACTABSTRACTThis study adds to the development of a non linear aeroelastic model which is destined to predict the behaviour of a thin flexible surface in contact with a flow under the hypothesis of an inviscid fluid. This fluid structure interaction model integrates a structure calculation, based on a membrane model, with a fluid calculation, based on a singularity method associated with a vortex method. The results on a J80 rig are compared to the experimentsin situ.RÉSUMÉCe travail est une contribution au développement d'un modèle d'aéroélasticité non linéaire, destiné à la prédiction de comportement de surfaces souples de faible épaisseur, soumises à un écoulement de fluide parfait. Ce modèle d'interaction fluide-structure intègre un calcul de structure basé sur un modèle de membrane à un calcul fluide tridimensionnel instationnaire, basé sur une méthode de singularités associée à une méthode particulaire. Les résultats sur un gréement de J80 sont comparés à des essaisin situ.

关键词： non-linear aeroelasticity membrane inviscid fluid fluid structure interaction testing aéroélasticité non linéaire membrane fluide parfait couplage fluide-structure expérimentation

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Interaction between wear processes and limit cycle oscillations of a control surface with free-play non-linearity

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING 2002年第G3期216卷 143-153页

作者： Safi, SA Kelly, DW Archer, RD Univ New S Wales Sch Mech & Mfg Engn Sydney NSW 2052 Australia

This paper provides a detailed study of a non-linear aeroelastic phenomenon first addressed by Safi et al., i.e. coupling a model for wear in mechanical linkages to the aeroelastic response of a non-linear wing-aileron or stabilizer-elevator system. The aeroelastic behaviour of these systems with free-play structural non-linearity in the control surface restoring moment is examined. The underlying dynamics and deterioration of the system due to ageing are investigated. Extensive numerical simulations are performed using Wagner's function to evaluate the aerodynamic forces. The resulting equations are integrated numerically to give time histories of the airfoil-aileron motion. Regions of limit cycle oscillations (LCOs) and chaotic vibration are identified well below the linear flutter speed. Finally qualitative and quantitative wear analyses are presented to provide relationships to predict the depth of wear in the mechanical connections experiencing LCOs. The problem is shown to be coupled with an accelerating wear rate as the free play develops.

关键词： non-linear aeroelasticity Control surface Free play control surfaces Aeroelastics liquid crystal on silicon depth of wear limit cycle oscillation nonlinearity wear

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