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Some NACA0015 profile support variants with self-excited vibration in subsonic fluid flow
Vlček, Václav ; Štěpán, M. ; Zolotarev, Igor ; Kozánek, Jan
One of the important domain of the contemporary aeroelasticity is the self-excited vibration of isolated profiles together with the self-excited vibration of profiles located in blade cascades. The Institute of Thermomechanics of the AS is engaged in group of projects concerning this aeroelastic problem. Results presented here were obtained solving a part of them [1-5].This experiments were realized in the wind tunnel of suction type placed in the laboratory of the Institute in Nový Knín. Profile NACA0015 with two degrees of freedom support was used. Profile was embedded with variable rotational and translational elasticity. The attention of this paper is concentrated on the time records and corresponding spectra of the translational and rotational movement during the self-excited vibration of the profile. Further results related to other parameters of this vibration will be published separately.
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On numerical approximation of fluid-structure interactions of air flow with a model of vocal folds
Valášek, J. ; Horáček, Jaromír ; Sváček, P.
This paper deals with flow driven vibration of an elastic body. Our goal is to develop and mathematically describe a simplified model of the human vocal fold. The developed numerical schemes for viscous incompressible fluid flow in ALE formulation and the elastic body are implemented by two solvers, specific for each domain. The studied problem is coupled by Dirichlet-Neumann boundary conditions. Both solvers are based on the finite element method. Particularly, for the fluid model the crossgrid elements are used. Numerical results focus on the verification of the developed program.
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On application of finite element method for approximation of 3D flow problems
Sváček, P. ; Horáček, Jaromír
This paper is interested to the interactions of the incompressible flow with a flexibly supported airfoil. The bending and the torsion modes are considered. The problem is mathematically described. The numerical method is based on the finite element method. A combination of the streamline-upwind/Petrov-Galerkin and pressure stabilizing/Petrov-Galerkin method is used for the stabilization of the finite element method. The numerical results for a three-dimensional problem of flow over an airfoil are shown.
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DYMAMESI 2014 - proceedings
Zolotarev, Igor ; Pešek, Luděk
Proceedings of the Colloquium DYNAMICS OF MACHINES AND MECHANICAL SYSTEMS WITH INTERACTIONS (DYMAMESI), that was held in the Institute of Thermomechanics in Prague, November 25 - 26, 2014 deal with problems structural and multibody dynamics, in coupled interacting systems as aero-elasticity, hydro-elasticity, biomechanics, systems with feedbacks and mechatronics. The published papers was divided into the two parts: Interactions - vibration of dynamic systems coupled with surroundings, mechanical systems with feedbacks, mechatronic active elements, measurement methods and identification in interaction problems, interactions in biomechanics, aero- and hydro-elasticity in rotational engines (bearings, blades, sealings, spaces), analytical and numerical methods in solutions of interactions and Dynamics of Machines - dynamics and vibrations of mechanical systems and solids, non-linear systems - stability, bifurcations, chaos, damping technologies - materials, active elements, methods, identification, vibrodiagnostics, fatigue, computational mechanics and experiments.
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Flutter at a low velocity
Vlček, Václav ; Kozánek, Jan ; Zolotarev, Igor
Aeroelastic experiments with the profile NACA0015 were realized in the suction type aerodynamic tunnel of the Institute of Thermomechanics, Czech Academy of Sciences, Prague. The profile had two degrees of freedom realized in translation and rotation motion and flow velocity was just up its critical value. The flow field was measured with interferometry method and the results obtained at the velocity M = 0.23 in the flutter regime are presented. The evaluation of interferogramms enabled to determine the components of the drag and lift forces.
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Analytical and numerical approach to the airfoil stability computation
Chládek, Štěpán ; Horáček, Jaromír
The fluid structure interaction (FSI) represents an important task in many applications. This paper deals with interaction of airfoil and fluid flow and compares two possible ways of computation of the stability boundaries of the system. The airfoil has two degrees of freedom represented by translation h(t) and rotation a(t). The flow acts on the airfoil with aerodynamic forces depending on the flow velocity. Two methods for calculation of the critical flow velocity, when the airfoil loses aeroleastic stability, are described.
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On mathematical modelling of gust response using the finite element method
Sváček, P. ; Horáček, Jaromír
In this paper the numerical approximation of aeroelastic response to sudden gust is presented. The fully coupled formulation of two dimensional incompressible viscous fluid flow over a flexibly supported structure is used. The flow is modelled with the system of Navier-Stokes equations written in Arbitrary Lagrangian-Eulerian form and coupled with system of ordinary differential equations describing the airfoil vibrations with two degrees of freedom. The Navier-Stokes equations are spatially discretized by the fully stabilized finite element method. The numerical results are shown.
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