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The new HPC results of 3D FE modelling of dry-friction damping at tie-boss couplings of bladed wheel - 6nd resonant mode
Pešek, Luděk ; Šnábl, Pavel ; Bula, Vítězslav
The paper is a direct continuation of our study published in the last colloquium DYMAMESI. This paper deals with the new results of dry-friction damping calculation of the bladed wheel with tie-boss couplings vibrating at a higher resonant mode, i.e. mode with 6 nodal diameters (ND). The numerical solution of the wheel based on 3D finite element method with surface-to-surface dry friction contact model is applied. Due to dry friction contacts and non-linear solution, it leads to HPC computations and long computation times. Therefore, the earlier proposed computational strategy for damping evaluation where the resonant attenuation is computed directly from the defined resonant initial conditions given by the 6ND mode is used. Comparison of experimental and numerical results of dynamical behaviour of the bladed wheel yields a reasonable agreement for the studied vibration mode.
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Simple model for investigation of aerodynamic coupling in linear blade cascades
Chládek, Štěpán ; Pešek, Luděk ; Procházka, Pavel P.
Simple viscous-elastic model has been proposed for investigation of aerodynamic coupling in linear blade cascades. One blade is connected with both adjacent blades using idealized springs and dampers which represent viscous fluid. All blades may oscillate with one degree of freedom represented by vertical translation. Energy method using travelling waves model was utilized for aerodynamic damping coefficient derivation. The proposed model does not compute the damping values quantitatively, nevertheless it provides the damping shape analysis. Interesting results are presented within zero and low subsonic flow velocities, where the experiment included velocity flow field measurement.
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The Effect of Angle of Attack on a Blade Cascade with Overlap
Procházka, Pavel P. ; Uruba, Václav ; Pešek, Luděk
This experimental study was carried out to study an aeroelastic coupling in the case of a blade cascade with overlap exposed to tunnel freestream of different angle of attack (AoA). Three of five blades were constructed to allow vertical position changing by the effect of three shakers. Particle Image Velocimetry was used to measure averaged velocity and dynamical parameters of the flow. Mainly, the effect of AoA will be discussed as well as the influence of blade enlargement and Re number. The influence of potential endplates will be indicated.
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A hybrid boundary element based aeroelastic model for flexible wing.
Prasad, Chandra Shekhar ; Pešek, Luděk
The paper describes development of medium delity aeroelastic numerical model for fast aeroelastic analysis of the flexible aeronautical structures e.g. wings, rotor blades etc. The numerical model is developed particularly for the incompressible low subsonic flow regime application. For the flow field modeling boundary element based hybrid panel method flow solver with viscous-inviscid coupling strategy have been successfully developed and implemented here.The unsteady flow field is modeled using hybrid/modi ed panel method where, integral boundary layer theory (vis-cous part), surface panel method (potential flow inviscid part) and vortex particle method (separated shear layer modeling) are coupled together. The proposed model can simulate both attached and separated flow fields. The estimated aerodynamic lift coefficients and the pressure coefficient are compared with experimental results for static and dynamic stall flow conditions. Furthermore, the results from new aeroelastic model will be compared with classical CFD-CSD based aeroelastic models for efficiency and accuracy check. The proposed methodology for the aeroelastic analysis of long exible aeronautical structure will provide researchers and engineers a fast, cost effective and efficient tool for aeroelastic analysis for different design at preliminary design stage where large numbers of design iteration are required within short time frame.
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Contribution to HPC FEM calculations of bladed disk dynamics with dry-friction contacts
Pešek, Luděk ; Šnábl, Pavel ; Bula, Vítězslav
The experimental set-up for studying dynamical behaviour of the bladed wheel with pre-stressed dry-friction contacts in tie-bosses was built. The numerical solution of the turbine bladed wheel with tie-bosses based on 3D finite element method with surface to surface dry-friction contact model is proposed. Comparison of experimental and preliminary numerical results of dynamical behaviour and damping estimation of our bladed wheel design yielded a reasonable agreement. Due to dry-friction contacts and non-linear solution of 3D FE model it, however, leads to HPC computations and long computation times. The contribution deals with description of computational strategy for damping evaluation and achieved results, too.
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