Reduced-Order Aeroelastic Models for Dynamics of Maneuvering Flexible Aircraft

2017

AIAA Journal

Self Cite

The single-shooting method is used to identify optimal manoeuvres in the lateral dynamics of partially-supported flexible wings. Efficient actuation strategies are sought when large wing deflections substantially modify the geometry of the vehicle during the manoeuvre. For that purpose, geometrical nonlinear models are first built using composite beams and an unsteady vortex lattice, and the optimal control problem is then solved via a gradient-based algorithm. A flight-dynamics model based on elastified stability derivatives is shown to capture the relevant dynamics either under slow actuation or for stiff wings and it is used as a reference. Embedding the full aeroelastic description into the optimisation framework expands the space of achievable manoeuvres, such as quick wing response with low structural vibrations or large lateral forces with minimal lift losses.

Section: -8mentioning

confidence: 99%

Optimal Rolling Maneuvers with Very Flexible Wings

Maraniello

2017

AIAA Journal

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“…The resulting low-order modeling approach has been demonstrated for fast transient analyses of maneuvering flexible aircraft following antisymmetric control surface inputs and load calculations in spanwise non-uniform discrete gust encounters. 27 Continuing on those studies, this work will investigate the application of the reduced-order modeling approach for WVE load calculations, which is characterized by independent disturbances on each aerodynamic panel, and subsequent design of a dynamic load alleviation system based on the coupled aeroelastic/flight-dynamic vehicle description.…”

Section: -26mentioning

confidence: 99%

“…The underlying models have been implemented in Imperial College's framework for Simulation of High Aspect Ratio Planes (SHARP), which includes static aeroelastic analyses, trim, linear stability analyses, and fully nonlinear time-marching simulations. 22,27,28,40,41 Here, we provide a brief description of the aerodynamic and flexible-body dynamic models in Sections II.A and II.B, respectively, which are used in Section II.C to obtain the simulation plant for the coupled flexible-aircraft dynamics. Modeling of the wake vortices, which appear as disturbance terms in the linearized UVLM, is covered in Section II.D.…”

Section: Flexible-aircraft Dynamics Simulation Modelmentioning

confidence: 99%

“…The model order of the resulting system, however, is too large for direct control synthesis and this is tackled by a model reduction approach that has been previously demonstrated on similar aeroelastic systems. 27 The resulting control model finally provides the basis for a 2-DOF feedforward and feedback control scheme using H ∞ control (Section III.B).…”

Section: Control System Designmentioning

confidence: 99%

“…The various modules in SHARP have been verified for this same platform in previous publications. 22,27,28,40,41,60 The characteristics of the vehicle will be briefly defined in Subsection IV.A. The aeroelastic/flight-dynamic simulation model is then exercised in Section IV.B to explore the effect of wake vortex strength, different encounter angles and displacement on the vehicle flight dynamic response.…”

Section: Numerical Studiesmentioning

confidence: 99%

See 2 more Smart Citations

Dynamic Load Alleviation in Wake Vortex Encounters

Hesse

Journal of Guidance, Control, and Dynamics

2016

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This paper introduces an integrated approach for flexible-aircraft timedomain aeroelastic simulation and controller design suitable for wake encounter situations. The dynamic response of the vehicle, which may be subject to large wing deformations in trimmed flight, is described by a geometrically-nonlinear finite-element model. The aerodynamics are modeled using the unsteady vortex lattice method and include the arbitrary

Aerodynamic load control in horizontal axis wind turbines with combined aeroelastic tailoring and trailing‐edge flaps

Kerrigan

et al. 2015

Wind Energy

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This paper presents an aeroservoelastic modeling approach to investigate dynamic load alleviation in large wind turbines with composite blades and trailingedge aerodynamic surfaces. The tower and rotating blades are modeled using geometrically-nonlinear composite beams, and linearized about reference rotating conditions with potentially arbitrarily-large structural displacements. The aerodynamics of the rotor are represented using a linearized unsteady vortexlattice method and the resulting aeroelastic system is written in a state-space description that is both convenient for model reductions and control design. A linear model of a single blade is then used to design an H ∞ regulator, capable of providing load reductions of up to 13% in closed-loop on the full wind turbine nonlinear aeroelastic model. When combined with passive load alleviation through aeroelastic tailoring, dynamic loads can be further reduced to 35%. While the separate use of active flap controls and passive mechanisms for load alleviation have been well-studied, an integrated approach involving the two mechanisms has yet to be fully explored and is the focus of this paper. Finally, the possibility of exploiting torsional stiffness for active load alleviation on turbine blades is also considered. IntroductionHorizontal-Axis Wind Turbines (HAWT) have been steadily increasing in size since they were first considered for large-scale energy production, both in terms of tower height and rotor diameter [Barlas and van Kuik(2010)]. At the time of writing, the largest wind turbines in operation have rotors measuring above 120 m in diameter, but rotors of up to 160 m are already being developed. Larger blades are necessarily more flexible and, as a result, aeroelastic effects previously not seen in smaller rotors are beginning to surface [Hansen et al.(2006)Hansen, Sørensen, Voutsinas, Sørensen, This has brought about new needs in terms of modeling requirements and poses new technological challenges, in particular, with respect to an increased need for methods of load alleviation to prolong fatigue life [Bottasso et al.(2013)Bottasso, Campagnolo, Croce, and Tib Passive load alleviation through aeroelastic tailoring is attractive in its simplicity, design and is now well understood [Shirk et al.(1986)Shirk, Hertz, and Weisshaar]. It relies on a blade structure designed with bend-twist coupling (twist-towardsfeather) to reduce the angle of attack as the blade bends upwards. This mod-1