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Aeroelastic experiments with the structural properties variation
Chládek, Štěpán ; Zolotarev, Igor ; Uruba, Václav
The paper measurements on a model of the airfoil NACA0012. Usually there is a limit range of the flow velocity in the wind tunnel. The chosen wind tunnel is usually fixed, the only one possibility is to modify the structural properties of the experimental stand. There are presented two kinds of modifications, one is based on the geometry variation, the other one on the added mass approach. Both of them have been verified experimentally.
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On higher-order space-time discretization of an nonlinear aeroelastic problem with the consideration of large displacements
Sváček, P. ; Horáček, Jaromír
This paper focuses on the mathematical and numerical modelling of interaction of the two-dimensional incompressible fluid flow and a flexibly supported airfoil section wit control section. A simplified problem is considered: The flow is modelled by the system of Navier-Stokes equations and the structure motion is described with the aid of nonlinear ordinary differential equations. The time-dependent computational domain is taken into account by the Arbitrary Lagrangian-Eulerian method. Higher order time discretization is considered within the stabilized finite element method. The application of the described method is shown.
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Forces actingon the fluttering. Profile in the wind tunnel
Vlček, Václav ; Kozánek, Jan ; Zolotarev, Igor
2D experiments with profile NACA0015 supported with two degrees of freedom in aerodynamic tunnel of suction type were realized. One degree of freedom was rotation around the profile axis in 1/3 chord distance behind the profile leading edge, the second one was the vertical translation. The interferometric visualization of the flow field in the vicinity of the profile during its self-excited vibration was realized. Forces acting on the profile and the pressure distribution on the profile surface resulting from the interferometric measurements are presented.
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Incompressible fiscous flow at viscous velocities in interaction with a vibrating profile NACA 0012
Honzátko, R. ; Horáček, Jaromír ; Kozel, Karel
The work presents numerical solution of the interaction of 2D incompressible viscous flow and a freely vibrating profile NACA 0012 with large amplitudes. The upstream flow velocities are consider in the range 5-40 m/s. The profile has two degrees of freedom. It can rotate around an elastic axis and oscillate in the vertical direction. Its motion is described by two nonlinear ordinary differential equations. Fourth-order Runge-Kutta method is used to solve these equations numerically. The incompressible Navier-Stokes equations represent the mathematical model of the laminar viscous flow. Numerical schemes of the FVM are applied on a structured Quadrilateral C-mesh. The method of artificial compressibility and dual-time stepping method is employed for numerical simulations. Deformations of the computational domain are treated using the ALE method. Numerical simulations of the profile motion are performed for the case solved earlier by the FE method, and the results are in good agreement.
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Zviditelnění nestacionárního proudění kolem vibrujícího profilu: Experimentální uspořádání a předběžné testy
Vlček, Václav ; Horáček, Jaromír ; Luxa, Martin ; Veselý, Jan ; Bula, Vítězslav
The contribution presents the designed aeroelastic model, experimental set-up and preliminary tests of optical measurements of flow field around a vibrating NACA 0017 profile elastically supported in the measurement section of the wind tunnel. The profile can vibrate with two degrees of freedom for translation and rotation. The interferometry method combined with the high speed filming was used for flow visualization of in different phases of the profile motion. The measurements were performed in a subsonic wind tunnel above the airflow velocity for loss of the system stability by flutter, thus the vibration amplitudes were relatively large up to about 7 mm for vertical translation and 16.5 degrees for angle of rotation around the elastic axis. The 52 images of the flow field were recorded during one oscillation period of the profile from which the pressure and velocity can be evaluated in the given time instants.
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Interakce tekutiny se strukturou
Feistauer, M. ; Horáček, Jaromír ; Kučera, V. ; Prokopova, J. ; Sváček, Petr
The paper is concerned with two subjects: flow induced airfoil vibrations and flow through channels with moving walls. This problem appears, for example, in the simulation of flow through human vocal folds. Discontinuous Galerkin FEM is promising robust method for the solution of compressible flow and in combination with the ALE method, it allows the solution of flow problems in time dependent domains.
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Dual-time stepping method applied to a numerical solution of unsteady incompressible flow with a vibrating profile
Honzátko, R. ; Horáček, Jaromír ; Kozel, K.
The paper presents numerical solution of two-dimensional incompressible flow in the interaction with a vibrating profile. The profile has two degrees of freedom. Mathematical model is represented either by the Euler equations in the case of inviscid flow or the Navier-Stokes equations in the case of viscous flow. Finite volume method is used as a discretization method. The dual-time stepping method is applied to unsteady simulations. This method provides a possibility to develop a time-accurate time-marching scheme for unsteady incompressible flows. Computational domain deformation due to the profile motion are treated using the Arbitrary Lagrangian-Eulerian method (ALE). Numerical schemes used for unsteady flow calculations are implemented in a form satisfying the geometric conservation law (GCL).
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Numerické simulace interakce proudu s leteckým profilem se třemi stupni volnosti
Růžička, M. ; Feistauer, M. ; Horáček, Jaromír ; Sváček, Petr
The subject of the paper is the numerical simulation of the interaction of two-dimensional incompressible viscous fluid and a vibrating airfoil with large deviations. The airfoil is considered as a solid body with three degrees of freedom. The airfoil performs rotation around an elastic axis, oscillations in the vertical direction and rotation of a flap. The nemerical simulation is based on the the finite element solution of the Navier-Stokes equations and the system of nonlinear ordinary differential equations deseribing the airfoil motion. The interaction and feedback phenomenon is numerically treated by a coupling procedure, which connects the structural problem and flow problem together. The timedependent computational domain and a moving mesh are taken into account with the aid of the Arbitrary Lagrangian-Eulerian (ALE) formulation. High Reynolds numbers up to 10 require the application of a suitable stabilizatin of the finite element discretization.
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Numerické simulace stlačitelného proudění v kanále s pohyblivou stěnou
Prokopova, J. ; Feistauer, M. ; Kučera, V. ; Horáček, Jaromír
This work is concerned with the simulation of inviscid compressible flow in time dependent domains. The special treatment is given to the ALE (Arbitrary Lagrangian-Eulerian) method. We present an ALE formulation of the Euler equations describing the compressible flow and discretize them. The space discretize them. The space discretization is carried out by the discontinuous Galerkin method and for the time discretization a semi-implicit scheme is used. In the end of the paper some computational results are presented.
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