Enhanced Modal Approach for Free-flight Nonlinear Aeroelastic Simulation of Very Flexible Aircraft

Ritter, Markus; Jones, Jessica R.; Cesnik, Carlos E. S.

doi:10.2514/6.2016-1794

Cited by 10 publications

(21 citation statements)

References 17 publications

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“…Separate research group efforts have developed aeroelastic framework capable of taking into account the nonlinear aspects of the VFA behavior. Examples of state of the art codes in this context cited on literature are UM/NAST (17,18,19) from University of Michigan, SHARPy (20,21,22,23) from London Imperial College, ASWING (24,25,26) from Massachusetts Institute of Technology, NATASHA (27,28) , from Georgia Institute of Technology, and DLR toolbox (29,30) , from Deutsches Zentrum für Luft-und Raumfahrt (DLR).…”

Section: Propeller Modeling On Nonlinear Aeroelastic Frameworkmentioning

confidence: 99%

“…In order to capture the interaction of propellers and aircraft lifting surfaces, a method capable of taking into account that mutual aerodynamic influence was necessary. For that purpose, the Unsteady Vortex Lattice method (UVLM) was selected, and a UVLM code developed by Ritter (43) was adapted and integrated to UM/NAST framework, as an additional aerodynamic option.…”

Section: Lifting Surfaces Aerodynamicsmentioning

confidence: 99%

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Propeller influence on the aeroelastic stability of High Altitude Long Endurance aircraft

Teixeira

Cesnik

2020

Aeronaut. j.

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This work investigates the propeller’s influence on the stability of High Altitude Long Endurance aircraft, incorporating all resultant loads at the propeller hub, propeller slipstream, and gyroscopic loads. Such effects are usually neglected in the aeroelastic simulation of HALE aircraft. For that goal, a previously developed framework, which couples a geometrically nonlinear structural solver with an Unsteady Vortex Lattice method (uVLM) for lifting surfaces and a Viscous Vortex Particle (VVP) method for propeller slipstream, was employed to generate time-data series. Also, a method, based on a combination of Proper Orthogonal Decomposition and system identification, to extract dynamic information (frequencies, damping, and modes) of the aircraft from a time-series signal is proposed and successfully tested for a purely structural case, for which reference data is available. The method is then applied to investigate the stability of aeroelastic cases. The results demonstrate that the presence of propellers can influence the aeroelastic stability of a Very Flexible Aircraft.

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Section: Propeller Modeling On Nonlinear Aeroelastic Frameworkmentioning

confidence: 99%

Section: Lifting Surfaces Aerodynamicsmentioning

confidence: 99%

Propeller influence on the aeroelastic stability of High Altitude Long Endurance aircraft

Teixeira

Cesnik

2020

Aeronaut. j.

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“…The core module coupling MSC Nastran SOL 400 with the VLM code is validated by analyzing the nonlinear aeroelastic static response of a highly flexible 16 m wing [23] and of the X-HALE risk reduction vehicle (RRV) [24] at a prescribed freestream velocity and angle of attack. The analyses are performed by assuming clamped boundary conditions at the root for the wing and at the wing centerline for the X-HALE.…”

Section: A Validation Of Nonlinear Aeroelastic Static Solvermentioning

confidence: 99%

“…The reference grid defining the support frame is chosen at the wing centerline in order to directly compare the trim deflection with the results from UM/NAST and the DLR toolbox. The analysis is performed using a step size equal to 20% [24], for which the solution converges 10% faster than with no relaxation.…”

Section: X-hale Rrvmentioning

confidence: 99%

Nonlinear Aeroelastic Trim of Very Flexible Aircraft Described by Detailed Models

Riso

Vincenzo²,

Ritter

et al. 2018

Journal of Aircraft

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This Paper presents an efficient algorithm for the nonlinear aeroelastic trim analysis of very flexible aircraft described by detailed models. The algorithm is based on a novel inertia relief technique for large displacements and is applicable to fluid-structure iteration frameworks coupling generic structural and aerodynamic solvers, including high-fidelity commercial solvers. The methodology is tested on a low-order model of the University of Michigan's X-HALE experimental vehicle in order to compare to reference results for a typical steady rectilinear flight condition. Nonlinear aeroelastic trim analyses conducted at different flight speeds show that the proposed approach gives a smooth and fast convergence to the trim solution, which makes it suitable for high-fidelity aeroelastic design of very flexible aircraft. Nomenclature a S 2 , a S 3

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“…In their works, they propose a series of nonlinear static finite element analyses to obtain the quadratic mode shape components. Ritter uses this idea for simulating the nonlinear aeroelastic gust responses of free-flying aircraft in [19]. Van Zyl seized upon the subject of quadratic mode shape components for T-tail flutter studies and proposes a method for computing the quadratic mode shape components based on linear finite element analyses [12].…”

Section: Introductionmentioning

confidence: 99%

T-tail flutter simulations with regard to quadratic mode shape components

Schäfer

2021

CEAS Aeronaut J

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It is known that the dynamic aeroelastic stability of T-tails is dependent on the steady aerodynamic forces at aircraft trim condition. Accounting for this dependency in the flutter solution process involves correction methods for doublet lattice method (DLM) unsteady aerodynamics, enhanced DLM algorithms, unsteady vortex lattice methods (UVLM), or the use of CFD. However, the aerodynamic improvements along with a commonly applied modal approach with linear displacements results in spurious stiffness terms, which distort the flutter velocity prediction. Hence, a higher order structural approach with quadratic mode shape components is required for accurate flutter velocity prediction of T-tails. For the study of the effects of quadratic mode shape components on T-tail flutter, a generic tail configuration without sweep and taper is used. Euler based CFD simulations are applied involving a linearized frequency domain (LFD) approach to determine the generalized aerodynamic forces. These forces are obtained based on steady CFD computations at varying horizontal tail plane (HTP) incidence angles. The quadratic mode shape components of the fundamental structural modes for the vertical tail plane (VTP), i.e., out-of-plane bending and torsion, are received from nonlinear as well as linear finite element analyses. Modal coupling resulting solely from the extended modal representation of the structure and its influence on T-tail flutter is studied. The g-method is applied to solve for the flutter velocities and corresponding flutter mode shapes. The impact of the quadratic mode shape components is visualized in terms of flutter velocities in dependency of the HTP incidence angle and the static aerodynamic HTP loading.

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Enhanced Modal Approach for Free-flight Nonlinear Aeroelastic Simulation of Very Flexible Aircraft

Cited by 10 publications

References 17 publications

Propeller influence on the aeroelastic stability of High Altitude Long Endurance aircraft

Propeller influence on the aeroelastic stability of High Altitude Long Endurance aircraft

Nonlinear Aeroelastic Trim of Very Flexible Aircraft Described by Detailed Models

T-tail flutter simulations with regard to quadratic mode shape components

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