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Modelling and analysis of two-dimensional static and dynamic aeroelasticity of Fish Bone Active Camber morphing aerofoils

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JOURNAL OF FLUIDS AND STRUCTURES 2024年 129卷

作者： Wu, Jun Woods, Benjamin K. S. Univ Bristol Dept Aerosp Engn Bristol BS8 1TR England Univ Oxford Dept Biol Oxford England

As a continuous and smooth morphing concept for aerofoils, the Fish Bone Active Camber (FishBAC) concept has demonstrated significant aerodynamic efficiency improvements over traditional hinged flaps. In this paper, to investigate the static and dynamic aeroelasticity of FishBAC aerofoils, an unsteady two dimensional coupled fluid-structure interaction model is developed, which includes the structural response of the FishBAC spine, skin, stringers, tendons and actuator, coupled to an unsteady aerodynamics model. The structural dynamic model is Timoshenko beam-theory-based, while the aerodynamic model is based on Peters' unsteady model. The static and dynamic aeroelasticity is studied after the model is validated. Results show that the increase in pulley rotational angle reduces the zero-lift angle of attack, while keeping the slope between the lift coefficient and angle of attack the same. A shorter morphing region closer to the trailing edge is beneficial for generating larger lift coefficient with the same tendon moment and angle of attack. Flutter occurs with the increase of the air speed. When the morphing end position is fixed at 0.9 chord, increasing the morphing length reduces the critical flutter speed significantly, with the second bending mode tending to drive instability. With the same morphing length, moving the morphing region closer to the leading edge increases the critical flutter speed, and the unstable mode changes from the second mode into the first mode.

关键词： Static aeroelasticity dynamic aeroelasticity Aerofoil morphing FishBAC concept Flutter

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Development of Efficient dynamic aeroelasticity Model for High Fidelity Pointing Accuracy Assessment of VLBI Earth-Based Radio Antennas

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INTERNATIONAL JOURNAL OF AERONAUTICAL AND SPACE SCIENCES 2020年第3期21卷 693-706页

作者： Nieto, Michelle Guzman Thomas, Paul, V ElSayed, Mostafa S. A. Saad, Mohamed Brown, Gary L. Hilliard, Lawrence M. Carleton Univ Ottawa ON K1S 5B6 Canada InterTron Solut Inc Vaudreuil Dorion PQ J7V 8P2 Canada NASA Goddard Space Flight Ctr Greenbelt MD 20771 USA

Modern Earth-based radio antennas of very-long-baseline interferometry system are furnished with robust control systems for their pointing control. Their pointing accuracy is critical to the quality of the radio wave-front captured. External disturbances, particularly those of wind gusts, produce a non-negligible dynamic aeroelastic response that degrades its pointing accuracy, and yet are not mitigated by the antenna's control system. In this paper, a high fidelity and efficient dynamic aeroelastic model of an earth-based antenna is developed which is used to study the effects of wind gusts on the antenna's pointing accuracy. Model order reduction of the antenna structural model is carried out using Craig-Bampton method taking into consideration the dominant modal characteristics of the antenna. The aerodynamic forces are approximated using the 2D Doublet-Lattice Method. The Davenport Spectrum is used to model aerodynamic turbulences near the earth surface. The developed dynamic aeroelastic model is employed to investigate the effects of discrete and random gusts on the pointing accuracy of the antenna. It is found that the deviation in the pointing angle is more prominent in thez(azimuth) direction and it displays a quadratic dependency with respect to the mean wind speed. This behavior is attributed to the inertial component of the aeroelastic response solution represented by the gravitational field acting on the center of gravity of the main reflector and the counterweights. The developed efficient aeroelastic model can be integrated into the antenna control system for its response prediction and mitigation.

关键词： VLBI Earth-based antenna Gust Devonport spectrum dynamic aeroelasticity Craig-Bampton Doublet-lattice method

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dynamic aeroelasticity of Wings with Tip Propeller by Using Navier-Stokes Equations

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AIAA JOURNAL 2019年第8期57卷 3200-3205页

作者： Guruswamy, Guru P. NASA Ames Res Ctr Computat Phys Branch Moffett Field CA 94035 USA

Aeroelastic computations are made for a flexible wing with a tip-propeller system designed for electric aircraft. Flow is modeled using the Navier-Stokes equations, and wing structures are modeled using plate finite elements. A time-accurate procedure is developed to embed the flexible wing in an overset grid topology along with rotating blades. Results are validated with existing data from wind-tunnel and potential flow computations. Aeroelastic responses are compared for the wing with and without a tip-propeller system. The present work extends the capabilities of current Navier-Stokes solvers to simulate the aeroelasticity of complex configurations and impacts the design of electric aircraft for urban transportation.

关键词： Navier Stokes Equations dynamic aeroelasticity Propeller Blades Rectangular Wing Wind Tunnel Tests Electric Aircraft Beam and Warming Scheme Potential Flow Reynolds Averaged Navier Stokes Wing Tip

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High-Fidelity Gradient-Based Wing Structural Optimization Including Geometrically Nonlinear Flutter Constraint

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AIAA JOURNAL 2023年第7期61卷 3045-3061页

作者： Jonsson, Eirikur Riso, Cristina Monteiro, Bernardo Bahia Gray, Alasdair C. Martins, Joaquim R. R. A. Cesnik, Carlos E. S. Univ Michigan Dept Aerosp Engn 1320 Beal Ave Ann Arbor MI 48109 USA Univ Michigan Ann Arbor MI 48109 USA Georgia Inst Technol Daniel Guggenheim Sch Aerosp Engn 275 Ferst Dr Northwest Atlanta GA USA

Lightweight high-aspect-ratio wings make aircraft more energy efficient thanks to their lower induced drag. Because such wings exhibit large deflections, design optimization based on linear flutter analysis of the wing undeformed shape is inadequate. To address this issue, we develop a framework for integrating a geometrically nonlinear flutter constraint, which considers in-flight deflections, into a high-fidelity gradient-based structural optimization. The wing mass and stress constraints are evaluated on a linear built-up (detailed) finite element model to capture realistic structural features. The geometrically nonlinear flutter constraint is based on a condensed low-order beam representation of the built-up finite element model, which captures the impact of in-flight deflections with tractable computational effort for optimization. The flutter constraint is differentiated with respect to the detailed structural model sizing variables using the adjoint method to enable large-scale optimizations. The framework is demonstrated by minimizing the mass of a wingbox model subject to the geometrically nonlinear flutter constraint along with stress and adjacency constraints. The geometrically nonlinear flutter constraint adds a penalty of up to 60% of the baseline mass due to the impact of in-flight deflections on the flutter onset speed and its mechanism. In contrast, a linear flutter constraint evaluated on the undeformed wing adds a mass penalty of only 10%. This methodology can help design energy-efficient aircraft with high-aspect-ratio wings, which require geometrically nonlinear flutter analyses early in the design cycle.

关键词： Structural Design and Development Finite Element Modeling Structural dynamics and Characterization Aircraft Components and Structure Nonlinear Aeroelastic Systems Aircraft Wing Design Structural Optimization Flutter Analysis Nonlinear Structural dynamics dynamic aeroelasticity

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Bifurcation-Diagram-Free Postflutter Response Constraint for Design Optimization

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AIAA JOURNAL 2023年第8期61卷 3449-3465页

作者： Riso, Cristina Cesnik, Carlos E. S. Epureanu, Bogdan I. Georgia Inst Technol Daniel Guggenheim Sch Aerosp Engn 275 Ferst Dr Northwest Atlanta 30332 Georgia Univ Michigan Dept Aerosp Engn 1320 Beal Ave Ann Arbor MI 48109 USA Univ Michigan Dept Mech Engn 2350 Hayward St Ann Arbor MI 48109 USA

This paper introduces a new metric to constrain postflutter responses of aeroelastic systems in design optimization. The new metric aggregates the recovery rate to equilibrium for a range of operating conditions, modes, and amplitudes, resulting in a scalar constraint that does not involve the bifurcation diagram. By generalizing damping-based flutter constraints, the formulation yields mathematical properties oriented toward gradient-based optimization. The approach is demonstrated by optimizing a typical section with a subcritical bifurcation using a gradient-based algorithm and finite-difference derivatives. The postflutter response constraint suppresses self-sustained oscillations below a given flow speed while minimizing the mass penalty, which avoids a conservative solution. This constraint can help design highly efficient aeroelastic systems with feasible postflutter dynamics. Future development of adjoint derivatives will enable large-scale gradient-based optimization.

关键词： Multidisciplinary Design Optimization Flutter Constraint Postflutter Response Constraint Bifurcation Theory dynamic aeroelasticity Nonlinear aeroelasticity

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Sliding-Window Matrix Pencil Method for Design Optimization with Limit-Cycle Oscillation Constraints

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AIAA JOURNAL 2024年第11期62卷 4170-4188页

作者： Golla, Tarun Kennedy, Graeme J. Riso, Cristina Georgia Inst Technol Daniel Guggenheim Sch Aerosp Engn 275 Ferst Dr Northwest Atlanta GA 30332 USA

This paper introduces a novel approach to constrain limit-cycle oscillations in design optimization. The approach builds upon a limit-cycle oscillation constraint that bounds the recovery rate to equilibrium, circumventing the need for bifurcation diagrams. Previous work demonstrated the constraint using approximate recovery rates obtained by evaluating the system state velocity for prescribed states. This work proposes a fully nonlinear matrix pencil method that accurately evaluates the recovery rate based on transient simulations. The proposed method captures the amplitude variation in the recovery rate using a short time window that slides along the time history of a quantity of interest. This sliding-window matrix pencil method is first verified for a typical section model. Sensitivity analyses identify guidelines to obtain accurate recovery rates efficiently. The system is then optimized subject to limit-cycle oscillation, flutter, and side constraints, and the results are compared with the ones based on approximate recovery rates. The sliding-window matrix pencil method allows the optimizer to produce a less conservative design while preventing limit-cycle oscillations at desired operating conditions and amplitudes. The approach introduced in this paper can facilitate the inclusion of limit-cycle oscillation considerations in the design phase of a broad class of nonlinear systems.

关键词： Design Optimization Gradient-Based Optimization dynamic aeroelasticity Nonlinear aeroelasticity Flutter Limit-Cycle Oscillations

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Assessment of low-altitude atmospheric turbulence models for aircraft aeroelasticity

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JOURNAL OF FLUIDS AND STRUCTURES 2020年第0期95卷 102981-102981页

作者： Deskos, Georgios del Carre, Alfonso Palacios, Rafael Natl Renewable Energy Lab Natl Wind Technol Ctr Golden CO 80401 USA Imperial Coll London Dept Aeronaut London England

We investigate the dynamic aeroelastic response of large but slow aircraft in low-altitude atmospheric turbulence. To this end, three turbulence models of increasing fidelity, namely, the one-dimensional von Karman model, the two-dimensional Kaimal model and full three-dimensional wind fields extracted from large-eddy simulations (LES) are used to simulate ambient turbulence near the ground. Load calculations and flight trajectory predictions are conducted for a representative high-aspect-ratio wing aircraft, using a fully coupled nonlinear flight dynamics/aeroelastic model, when it operates in background atmospheric turbulence generated by the aforementioned models. Comparison of load envelopes and spectral content, on vehicles of varying flexibility, shows strong dependency between the selected turbulence model and aircraft aeroelastic response (e.g. 58% difference in the predicted magnitude of the wing root bending moment between LES and von Karman models). This is mainly due to the presence of large flow structures at low altitudes that have comparable dimensions to the vehicle, and which despite the relatively small wind speeds within the Earth boundary layer, result in overall high load events for slow-moving vehicles. Results show that one-dimensional models that do not capture those effects provide fairly non-conservative load estimates and are unsuitable for very flexible airframe design. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Atmospheric turbulence Gust loads Geometrically-nonlinear structures dynamic aeroelasticity Flight mechanics Large-eddy simulation

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A transonic, viscous nonlinear frequency domain Vortex Lattice Method for aeroelastic analyses

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JOURNAL OF FLUIDS AND STRUCTURES 2021年 107卷 103406-103406页

作者： Parenteau, Matthieu Laurendeau, Eric Polytech Montreal Mech Engn Dept 2500 Chemin Polytech Montreal PQ H3T 1J4 Canada

The Unsteady Vortex Lattice Method has interesting capabilities for nonlinear subsonic aeroelastic analyses. This paper aims to develop an aeroelastic framework based on the UVLM that is suitable for compressible, transonic and viscous unsteady flows. To achieve these modeling capabilities, the UVLM is first extended to the nonlinear frequency domain using the harmonic balance approach. Secondly, sectional corrections are applied from a steady 2D/2.5D database of aerodynamic forces computed with highfidelity Euler/RANS flow solvers. The angle of attack coupling scheme on the lift force is complemented by a least-square procedure also coupling the pitching moment. Finally, an approximation of the retarded time is implemented in the influence kernel of the harmonic balance formulation of the UVLM to account for unsteady compressibility. The aerodynamic model is verified against time domain high-fidelity solutions with pitching airfoils in 2D and in 3D with a pitching constant chord NACA 0012 swept wing. Thereafter, the HB/LCO approach is applied with the frequency domain UVLM to 2D and 3D aeroelastic problems and compared against high-fidelity solutions. The proposed framework is capable of capturing strong nonlinear Limit Cycle Oscillation behaviors at high Mach numbers, as well as the flutter boundary for a wide range of Mach numbers while maintaining a low computational cost. As a result, the proposed framework could be of interest for preliminary design and Multi-Disciplinary Design (MDO) optimizations in the context of subsonic and transonic aircraft design. (c) 2021 Elsevier Ltd. All rights reserved.

关键词： Unsteady Vortex Lattice Method Harmonic balance Flutter LCO Unsteady compressibility Non-linear frequency domain dynamic aeroelasticity

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A non-intrusive geometrically nonlinear augmentation to generic linear aeroelastic models

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JOURNAL OF FLUIDS AND STRUCTURES 2021年 101卷 103222-103222页

作者： Cea, Alvaro Palacios, Rafael Imperial Coll London Dept Aeronaut London England

A new approach to build geometrically-nonlinear dynamic aeroelastic models is proposed that only uses information typically available in linear aeroelastic analyses, namely a generic (linear) finite-element model and frequency-domain aerodynamic influence coefficient matrices (AICs). Good computational efficiency is achieved through a two-step process: Firstly, a geometric reduction of the structure is carried out through static or dynamic condensation on nodes along the main load paths of the vehicle. Secondly, manipulation of the resulting linear normal modes (LNMs), the condensed stiffness and mass matrices, and the nodal coordinates provides the modal coefficients of the intrinsic beam equations along these load paths. This preserves the LNMs of the original problem and augments them with the geometrically nonlinear terms of beam theory. The structural description is in material coordinates and modal AICs are thus naturally included as follower forces. Numerical examples include cantilever wings built using detailed models, for which effects such as nonlinear aeroelastic equilibrium, nonlinear dynamics and structural-driven limit-cycle oscillations are shown. Results demonstrate the ability of the methodology to seamlessly and efficiently incorporate critical nonlinear effects to (linear) arbitrarily large aeroelastic models of high aspect ratio wings. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： dynamic aeroelasticity High-aspect ratio wings Geometrically-nonlinear structures Reduced-order models

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Global Sensitivity Analysis of Shockwave Location during Transonic Flight

Global Sensitivity Analysis of Shockwave Location during Tra...

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AIAA Aviation Forum

作者： Robinson, Brandon Yuan, Weixing Poirel, Dominique Carleton Univ Dept Civil & Environm Engn Ottawa ON K1S 5B6 Canada Natl Res Council NRC Canada Aerosp Res Ctr Ottawa ON K1A 0R6 Canada Royal Mil Coll RMC Canada Dept Mech & Aerosp Engn Kingston ON K7K 7B4 Canada

ISBN: (数字)9781624105982

ISBN: (纸本)9781624105982

This study was inspired by the significant variation that may be observed in the numerical analysis of the pressure distribution over airfoils in transonic flight conditions. Our ability to predict the location of the formation of localized shockwaves is directly dependent on the accuracy of the pressure distributions obtained from the computational fluid dynamics (CFD) simulations. In dynamic aeroelasticity, the location of these shockwaves has a significant influence on flutter predictions. This paper provides a qualitative study of the sensitivity of the pressure coefficient (C-p) to certain parameters of interest, before delving into a formal global sensitivity analysis (GSA). The GSA is performed by constructing a polynomial chaos expansion (PCE) surrogate model of the output, namely the shockwave location.

关键词： Sensitivity Analysis Transonic Flight Computational Fluid dynamics Simulation Numerical Analysis Reynolds Averaged Navier Stokes dynamic aeroelasticity Angle of Attack Aerodynamic Configurations Wind Tunnel Walls Probability Density Functions

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