References of "Andrianne, Thomas"
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See detailLimit Cycle Oscillations of a Delta Wing in a Low Speed Wind Tunnel
Korbahti, Banu; Kagambage, Emile ULg; Andrianne, Thomas ULg et al

in Proceedings of ISMA2010 (2010, September 22)

Limit cycle oscillations involving Delta wings are an important area of research in modern aeroelasticity. Such phenomena can be the result of structural or aerodynamic nonlinearity. In this paper, a ... [more ▼]

Limit cycle oscillations involving Delta wings are an important area of research in modern aeroelasticity. Such phenomena can be the result of structural or aerodynamic nonlinearity. In this paper, a flexible half-Delta wing is tested in a low speed wind tunnel in order to investigate its dynamic response. Specifically, an investigation to determine the effects of a steady angle of attack on nonlinear Limit Cycle Oscillations (LCO) of a delta wing-plate model in low subsonic flow has been undertaken. It was found that, at several combinations of airspeed and angle of attack, the wing undergoes limit cycle oscillations. Two types of such oscillations are observed. One of them is low amplitude, low complexity limit cycle oscillations that occur at lower airspeeds; the other is high amplitude, high complexity limit cycle oscillations that occur a higher airspeeds and can appear abruptly. Some of the LCOs are the result of a subcritical Hopf bifurcation occurring at low steady angles of attack. At higher angles, a nontypical bifurcation was observed, whereby LCOs appear, grow with airspeed but then diminish and finally disappear as the airspeed is increased further. [less ▲]

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See detailBifurcation analysis of a wing undergoing stall flutter oscillations in a wind tunnel
Norizham, Abdul Razak ULg; Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

in Proceedings of ISMA2010 (2010, September 20)

Stall flutter is a Limit Cycle Oscillation (LCO) caused by the periodic separation of the flow around a wing immersed in a uniform fluid flow. The separation could be either partial or complete [1]. The ... [more ▼]

Stall flutter is a Limit Cycle Oscillation (LCO) caused by the periodic separation of the flow around a wing immersed in a uniform fluid flow. The separation could be either partial or complete [1]. The work presented focuses on a wing undergoing stall flutter in the pitch degree of freedom. The phenomenon is analyzed from the structural and aerodynamic response perspectives. The objective of this study is to promote the understanding of stall flutter by characterizing the complete bifurcation behavior of the selected system. The wing section chosen for this study is NACA 0018 profile applied to a rectangular wing. The tests are carried out at different airspeeds and angles of attack. The measured aeroelastic responses are analyzed and the behavior of the dynamic system is characterized by fully describing its bifurcation. Structural accelerations as well as unsteady pressures around the mid-span point of the wing are measured and examined. Furthermore, flow field visualization by means of the Particle Image Velocimetry technique is used to demonstrate aspects of the unsteady flow field, such as the manifestation of separation and vortices. [less ▲]

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See detailEtude du comportement aéroélastique des structures soumises à des écoulements décrochés
Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

Conference (2010, March 02)

L'objectif du travail de recherche est le développement d'un modèle numérique simulant les phénomènes aéroélastiques affectant les corps non-profilés, caractérisés par des effets de décrochage/raccrochage ... [more ▼]

L'objectif du travail de recherche est le développement d'un modèle numérique simulant les phénomènes aéroélastiques affectant les corps non-profilés, caractérisés par des effets de décrochage/raccrochage du fluide.L'application de ce modèle aux tabliers de point est prévue. [less ▲]

Detailed reference viewed: 60 (23 ULg)
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See detailProper Orthogonal Decomposition of Unsteady Aerodynamic Flows
Andrianne, Thomas ULg; Ligot, Jerome; Dimitriadis, Grigorios ULg

Report (2009)

This work constitutes the final report for a project funded by the Fonds de la Recherche Scientifique. The objective of the project was to acquire and install Par- tical Image Velocimetry (PIV) hardware ... [more ▼]

This work constitutes the final report for a project funded by the Fonds de la Recherche Scientifique. The objective of the project was to acquire and install Par- tical Image Velocimetry (PIV) hardware in the University of Liege Wind Tunnel facility in order to carry out the Proper Orthogonal Decomposition (POD) of un- steady aerodynamic flows. The characteristics and installation of the PIV system are described in the present report. Furthermore, the application of POD analysis to three different visualized flow cases is detailed. The flow cases were: flow be- hind a circular cylinder and separated flow over a rectangular wing. In all cases, emphasis was given to the combination of unsteadiness caused by both boundary layer separation and movement of the wind tunnel model. It is shown that the de- composition of flowfields that combine these two sources of unsteadiness is possible and informative. [less ▲]

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See detailAnalysis of dynamic response of a very flexible Delta wing model in a wind tunnel
Barbason, Mathieu ULg; Andrianne, Thomas ULg; Hickey, Daryl ULg et al

in Proceedings of the 2009 International Forum on Aeroelasticity and Structural Dynamics (2009, July)

Limit cycle oscillations involving Delta wings are an important area of research in modern aeroelasticity. Such phenomena can be the result of geometric nonlin- earity, aerodynamic nonlinearity or under ... [more ▼]

Limit cycle oscillations involving Delta wings are an important area of research in modern aeroelasticity. Such phenomena can be the result of geometric nonlin- earity, aerodynamic nonlinearity or under-wing store nonlinearity. In this paper, a flexible half-Delta wing without stores is tested in a low speed wind tunnel in order to investigate its dynamic response. It is found that, at several combinations of airspeed and angle of attack, the wing undergoes high amplitude limit cycle oscillations. Three types of such oscillations are observed. Type 1 oscillations occur only at low angles of attack and are the result of a Hopf-type bifurcation. Type 2 limit cycle oscillations occur at intermedi- ate angles of attack and are the result of an atypical bifurcation. In other words, these oscillations appear as the airspeed is increased but disappear at even higher airspeeds. Type 3 oscillations occur at even higher angles of attack. A bispectrum analysis shows that type 3 limit cycle oscillations feature quadratic phase coupling. No such coupling was measured for type 2 oscillations, leading to the conclusion that the nonlinearity must be of higher order. [less ▲]

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See detailUsing the Discrete Vortex Method to Simulate the Stall Flutter Phenomenon
Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

in Proceedings of the 2009 International Forum on Aeroelasticity and Structural Dynamics (2009, June)

The Discrete Vortex Method (DVM) has been recently used by several researchers in order to simulate the dynamic stall phenomenon on 2D airfoils oscillating at high angles of attack or undergoing stall ... [more ▼]

The Discrete Vortex Method (DVM) has been recently used by several researchers in order to simulate the dynamic stall phenomenon on 2D airfoils oscillating at high angles of attack or undergoing stall flutter oscillations. The aim of the present work is to investigate whether such simulations are representative of the true physics governing such oscillation. A DVM method is described and implemented. A basic validation of the method is performed on the case of an impulsively started static airfoil at a low angle of attack. It is shown that the steady state lift value obtained from the DVM method agrees with experimental measurements. Subsequently, a DVM simulation is performed for the case of a NACA 0012 airfoil undergoing symmetric stall flutter oscillations. The simulation results are compared to experimental results. It is shown that, while the general shape of the simulated lift variation with time agrees with the experiment, there are significant mean value and phase differences between experiment and simulation. Several justifications are suggested and improvements to the DVM simulation proposed. [less ▲]

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See detailWind tunnel investigation of the stall flutter oscillations of a bridge deck
Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

in Proceedings of the 8th National Congress on Theoretical and Applied Mechanics (2009, May)

Torsional Stall Flutter (TSF) is a one degree of freedom, self-excited phenomenon induced by the periodic separation/re-attachment of the flow around a body. The present paper proposes an experimental ... [more ▼]

Torsional Stall Flutter (TSF) is a one degree of freedom, self-excited phenomenon induced by the periodic separation/re-attachment of the flow around a body. The present paper proposes an experimental investigation of TSF on a bridge deck. A section model free to oscillate in torsion is tested in a low-speed wind tunnel. Static and dynamic tests are performed to enable a complete interpretation of the phenomena involved. For low airspeeds, the Karman vortex shedding excites the structure, resulting in small oscillations at the vortex shedding frequency. For high airspeeds, the deck undergoes Limit Cycle Oscillations (LCO) due to the TSF phenomenon. Nevertheless the Karman vortex shedding excitation is still present and appears in the measured forces signals. Peaks and troughs in the lift coefficient are detected for each pitching period. They are interpreted as the separation/re-attachment of the flow around the deck. The large amplitudes motion of the deck undergoing TSF reduces the amplitude of the aerodynamic lift coefficient. [less ▲]

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See detailIdentification des coefficients de couplage aéroélastique d'une section de pont en soufflerie.
Andrianne, Thomas ULg

Master's dissertation (2005)

Le domaine de l'aéroélasticité en génie civil s'est largement développé durant les dernières décennies. Béné ciant des travaux antérieurs réalisés en aéronautique, l'aéroélasticité des ouvrages d'art a ... [more ▼]

Le domaine de l'aéroélasticité en génie civil s'est largement développé durant les dernières décennies. Béné ciant des travaux antérieurs réalisés en aéronautique, l'aéroélasticité des ouvrages d'art a développé ses caractéristiques propres, centrées essentiellement sur les problèmes d'écoulement autour des corps non pro lés. Ces problèmes peuvent être classés dans les caté- gories suivantes: oscillation due à l'éjection tourbillonnaire, mouvement de galop, ottement et e orts dus à un vent turbulent. Chaque phénomène est étudié sur base de théories dédicacées, couplées aux études expérimentales. En particulier, le comportement aéroélastique des ponts suspendus a été abordé sur le plan expérimental et analytique depuis l'e ondrement du pont de Tacoma Narrows en 1940 aux États-Unis. Le présent travail propose une approche du comportement aéroélastique du plus haut viaduc jamais conçu: le viaduc de Millau. On propose d'étudier le tablier de cet ouvrage d'art au sein de la sou erie subsonique de l'Université de Liège. Une section du tablier vibre sous le vent grâce à un système de suspension spéci que développé par l'Université de Liège. Cette approche permet de mettre en évidence les di érents phénomènes aéroélastiques, ainsi que les instabilités aérodynamiques qui apparaissent. L'étude aéroélastique du tablier que l'on propose consiste à identi er les coe cients aéroélastiques introduits par Scanlan. Les coe cients aéroélastiques sont des fonctions adimensionnelles qui dépendent uniquement de la géométrie de l'ouvrage. Ils sont introduits ultérieurement dans l'analyse du comportement global de la structure et restent utilisables si des changements de masse ou d'inertie sont e ectués durant la conception de l'ouvrage. Les essais réalisés dans ce travail permettent de mieux comprendre les phénomènes aéroélastiques en jeu et de dé nir les marges de sécurité de l'ouvrage concerné. L'étude des di érentes parties d'un tel ouvrage dans une sou erie est de plus en plus fréquente dans le domaine du génie civil, ce qui permet la construction d'ouvrages de plus en plus audacieux... [less ▲]

Detailed reference viewed: 107 (12 ULg)