Dynamic Load Alleviation in Wake Vortex Encounters

Hesse, Henrik; Palacios, Rafael

doi:10.2514/1.g000715

Cited by 24 publications

(24 citation statements)

References 42 publications

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“…This approach was then shown to successfully predict the characteristics of T-tail flutter [19], which depend strongly on static loading and in-plane vibrations and are not captured by the standard DLM. Coupling with linearized geometrically-exact beam models also allows deriving state-space descriptions of both very flexible aircraft and horizontal-axis wind turbines suitable for control synthesis and design [20,21].…”

Section: Introductionmentioning

confidence: 99%

“…Hesse and Palacios [21] have recently proposed an internal balancing reduced-order modelling (ROM) strategy for unsteady aerodynamic problems around non-zero reference conditions. However, this is inefficient for large-scale models with tens of thousands of states or more, as it relies on a standard direct balancing method built on singular-value decomposition (SVD) [30][31][32], which neither exploits sparsity or low-rank structures in the UVLM state-space matrices [26,33].…”

Section: Introductionmentioning

confidence: 99%

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State-Space Realizations and Internal Balancing in Potential-Flow Aerodynamics with Arbitrary Kinematics

Maraniello

Palacios

2019

AIAA Journal

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This paper presents a general state-space realization of the unsteady vortex-lattice method together with a bespoke model-order reduction strategy. The aim is to provide a computationally-efficient aerodynamic description suitable for integration in aeroelasticity with arbitrary kinematics. The state-space realization is obtained from linearization, around arbitrary geometries and static loading conditions, of lifting surfaces and their free wakes. All components of the forces are evaluated in time domain using Joukowski's the

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

State-Space Realizations and Internal Balancing in Potential-Flow Aerodynamics with Arbitrary Kinematics

Maraniello

Palacios

2019

AIAA Journal

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“…Within the broader field of unsteady aerodynamics, a body of research has focused on the aerodynamic response of wings to natural and man-made gusts. These include the unsteady flows around large buildings [1], in the airwake of ships [2], or incidental interactions with the wakes of aircraft [3,4] or rotors [5], including wind turbines. There has also been considerable effort invested into the creation of analogs of those gusts for further research, as outlined in the following.…”

Section: Introductionmentioning

confidence: 99%

Vortical Gusts: Experimental Generation and Interaction with Wing

Hufstedler

McKeon

2019

AIAA Journal

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We describe the experimental generation of isolated vortical gusts and the interaction between these gusts and a downstream airfoil at a Reynolds number of 20,000. A standard method of generating a vortical gust has been to rapidly pitch an airfoil. A different approach is presented here: heaving a plate across a tunnel and changing direction rapidly to release a vortex. This method is motivated by the desire to limit a test article's exposure to the wake of the gust generator by moving it to the side of the tunnel. Two suites of experiments were performed to characterize the performance of the gust generators and to measure the forces on and flow around the downstream airfoil. The novel mechanism allowed for measurement of the resumption of vortex shedding from the downstream airfoil, which was impossible with the pitching generator. Nomenclature C L = lift coefficient, lift/(dynamic pressure × wing area) c a = airfoil chord length, m c p = plate chord length, m h = plate heave distance, m Re c = Reynolds number with respect to airfoil's chord length S = heaving speed ratio, V heave ∕U T = heaving time ratio, t heave ∕t cp t = time, s t a = normalized plate acceleration time, t accel ∕t cp t accel = plate acceleration time, s t c = chordwise convective time across airfoil, s t cp = chordwise convective time across plate, s t heave = heaving time, s t p = normalized airfoil pitching time, t pitch ∕t c t pitch = generator pitching time, s U = freestream speed, m∕s u = velocity in x direction, m∕s V heave = plate heaving speed, m∕s v = velocity in y direction, m∕s x = streamwise coordinate, m x 0 = streamwise position computed from unwrapping process, m y = cross-stream coordinate with respect to tunnel midline, m y 0 = initial plate distance from midline, m y peak = cross-stream position of maximum displacement of heaving plate, m y plate = cross-stream position of heaving plate, m y upstream = cross-stream position of pitching gust generator, m z = spanwise coordinate, m α = angle of attack of test article, rad (unless otherwise noted) α 1 = initial angle of pitching gust generator, rad (unless otherwise noted) α 2 = final angle of pitching gust generator, rad (unless otherwise noted) α eff = effective angle of attack of heaving gust generator, rad (unless otherwise noted) α upstream = angle of attack of pitching gust generator, rad (unless otherwise noted) Γ v = circulation of shed vortex, m 2 ∕s Γ v;est;heave = estimated circulation of shed vortex from heaving generator, m 2 ∕s Γ v;est;pitch = estimated circulation of shed vortex from pitching generator, m 2 ∕s Γ 2 = vortex identification criterion Δx = streamwise distance between generator and test article, m τ a = normalized time, t∕t c ω z = vorticity measured in x-y plane, s −1

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“…It features a versatile interface and core code written in Python 3, while computationally expensive routines are included in libraries coded in C++ and Modern Fortran. SHARPy is easily extended through a modular object-oriented design, and includes tools for linear and nonlinear analysis of the time-domain aeroelastic response of flexible bodies in a large number of cases, such as 3-D discrete gust (Del Carre et al, 2019), turbulent field input (Deskos, del Carre, & Palacios, 2019;Hesse & Palacios, 2016), control surface deflection and prescribed motion . In addition, linearised state-space models can be obtained for frequency domain analysis, controller design and model reduction.…”

Section: Discussionmentioning

confidence: 99%

SHARPy: A dynamic aeroelastic simulation toolbox for very flexible aircraft and wind turbines

Carre¹,

Muñoz-Simón²,

Goizueta³

et al. 2019

JOSS

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Aeroelasticity is the study of the dynamic interaction between unsteady aerodynamics and structural dynamics on flexible streamlined bodies, which may include rigid-body dynamics. Industry standard solutions in aeronautics and wind energy are built on the assumption of small structural displacements, which lead to linear or quasi-linear theories. However, advances in areas such as energy storage and generation, and composite material manufacturing have fostered a new kind of aeroelastic structures that may undergo large displacements under aerodynamic forces.In particular, solar-powered High-Altitude Long-Endurance (HALE) aircraft have recently seen very significant progress. New configurations are now able to stay airborne for longer than three weeks at a time. Extreme efficiency is achieved by reducing the total weight of the aircraft while increasing the lifting surfaces' aspect ratio. In a similar quest for extreme efficiency, the wind energy industry is also trending towards longer and more slender blades, specially for off-shore applications, where the largest blades are now close to 100-m long.These longer and more slender structures can present large deflections and have relatively low frequency structural modes which, in the case of aircraft, can interact with the flight dynamics modes with potentially unstable couplings. In the case of offshore wind turbines, platform movement may generate important rotor excursions that cause complex aeroelastic phenomena which conventional quasi-linear methods may not accurately capture.

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Dynamic Load Alleviation in Wake Vortex Encounters

Cited by 24 publications

References 42 publications

State-Space Realizations and Internal Balancing in Potential-Flow Aerodynamics with Arbitrary Kinematics

State-Space Realizations and Internal Balancing in Potential-Flow Aerodynamics with Arbitrary Kinematics

Vortical Gusts: Experimental Generation and Interaction with Wing

SHARPy: A dynamic aeroelastic simulation toolbox for very flexible aircraft and wind turbines

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