Počet nalezených dokumentů: 2874
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Flow Dynamics in the Vicinity of Tandem Buildings
Gnatowska, R.; Kellnerová, Radka; Uruba, Václav
2017 - anglický
The flow-field in the vicinity of tandem building model in a wind tunnel will be subjected to analysis of dynamics. The model is 3D consisting of the two blocks of different sizes arranged in a streamwise direction. Experiments were performed using time-resolved PIV technique in several measuring planes to capture both spatial and dynamical features. Klíčová slova: PIV experiment; tandem building arrangement; wind tunnel Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Flow Dynamics in the Vicinity of Tandem Buildings

The flow-field in the vicinity of tandem building model in a wind tunnel will be subjected to analysis of dynamics. The model is 3D consisting of the two blocks of different sizes arranged in a ...

Gnatowska, R.; Kellnerová, Radka; Uruba, Václav
Ústav termomechaniky, 2017

Impact of Turbulence Generators on Turbulent Characteristics and Structures
Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk
2017 - anglický
The turbulent generators are routinely used to produce very turbulent flows. Special type of vertically slenderize spires are applied to enhance turbulent diffusion from the surface upwards in order to increase the boundary layer depth. This paper studies the influence of variable upstream distance of generators on formation of both vortical and non-vortical organized structures within a test section. The 2-component 2-dimensional time-resolved particle image velocimetry measurement of the flow was performed in the wind channel with very rough surface. Intermittent flow dynamics was evaluated by means of higher order moments, vorticity, quadrant and wavelet analysis. The downstream evolution of the flow suggests that equilibrium between roughness- and spires-produced turbulence was reached at the distance of 7 spires height.\n Klíčová slova: turbulence generator; wind channel; vorticity; quadrant analysis Dokument je dostupný na externích webových stránkách.
Impact of Turbulence Generators on Turbulent Characteristics and Structures

The turbulent generators are routinely used to produce very turbulent flows. Special type of vertically slenderize spires are applied to enhance turbulent diffusion from the surface upwards in order ...

Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk
Ústav termomechaniky, 2017

Application of non-contact vibration measurements on a 48“ blade under low load condition
Kubín, Z.; Liška, J.; Míšek, T.; Procházka, Pavel
2017 - anglický
The paper describes in detail a Tip-Timing measurement on a combined cycle power plant with a steam turbine power output of 270MW. Newly developed magnetoresistive and optical sensors were used as well as standard eddy-current sensors to measure blade vibration under low load condition and variable back pressure. New hardware solution for the Tip-Timing measurement will is presented as well as results of measurements of relative amplitudes and excited nodal diameters. Klíčová slova: steam turbine; non-contact vibration measurement; magnetoresistive sensor; optical sensor Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Application of non-contact vibration measurements on a 48“ blade under low load condition

The paper describes in detail a Tip-Timing measurement on a combined cycle power plant with a steam turbine power output of 270MW. Newly developed magnetoresistive and optical sensors were used as ...

Kubín, Z.; Liška, J.; Míšek, T.; Procházka, Pavel
Ústav termomechaniky, 2017

Some experimentally determined properties of a profile in case of self-excited oscillations in subsonic flow
Vlček, Václav; Zolotarev, Igor; Kozánek, Jan; Šidlof, Petr; Štěpán, M.
2017 - anglický
In the wind tunnel of the Institute of Thermomechanics of the AS CR,v .v. i., experiments were realized with the profile NACA0015 in the presence of the self-excited oscillation. The oscillation of the profile with pitch and plunge degrees of freedom was excited by the subsonic air flow. The plunge support had the same elasticity for all experiments, the pitch support had seven different values of elasticity. Within experiments different types of self-excited vibration (flutter, stall flutter, deep stall flutter) were realized. Range of Mach numbers were M=0.08–0.45, when the chord length is used as the characteristic dimension of the profile. The frequency and amplitude characteristics of the oscillating profile were experimentally determined.\n Klíčová slova: airfoil; aeroelasciticy; dynamic stall; stall flutter; limit cycle oscillations; self -excited vibrations Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Some experimentally determined properties of a profile in case of self-excited oscillations in subsonic flow

In the wind tunnel of the Institute of Thermomechanics of the AS CR,v .v. i., experiments were realized with the profile NACA0015 in the presence of the self-excited oscillation. The oscillation of ...

Vlček, Václav; Zolotarev, Igor; Kozánek, Jan; Šidlof, Petr; Štěpán, M.
Ústav termomechaniky, 2017

Aspects of energy storage systems focusing on flywheel technologies
Zapoměl, Jaroslav; Kozánek, Jan
2017 - anglický
The energy storage devices are used to reduce variation of the power transmitted in complex technological systems. The individual technologies are based on different physical principles and are applicable in different industrial fields. This paper focuses on aspects of the flywheel storage devices that have a direct impact on their design, technological parametres, and extent of their application. Klíčová slova: energy storage systems; flywheel technology; ultra-low friction bearings Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Aspects of energy storage systems focusing on flywheel technologies

The energy storage devices are used to reduce variation of the power transmitted in complex technological systems. The individual technologies are based on different physical principles and are ...

Zapoměl, Jaroslav; Kozánek, Jan
Ústav termomechaniky, 2017

Proposal of hyperelastic proportional damping as dissipated energy model of hard rubbers
Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Košina, Jan; Cibulka, Jan
2017 - anglický
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to find the dependency the dissipated energy on the deformation energy. Based on the results of an experiment, a function of dissipation energy of hard rubbers for finite strains using the theory hyperelasticity was proposed herein analogically as a proportional damping for elastic theory. Samples of hard rubber of different hardness (EPDM, Silicone) were dynamically tested on the developed torsional test-rig at different frequencies, amplitudes. First the Mooney Rivlin model (MRM) for a shear case of loading was analytically developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. These constants were used to obtain the deformation energy of the MRM models. The coefficients of hyperelastic proportional damping relating a dissipated energy to a strain energy were evaluated for tested rubbers on the basis of experimental results. Klíčová slova: torsion vibration; large deformation; hyperelasticity; dissipated energy; deformation energy Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Proposal of hyperelastic proportional damping as dissipated energy model of hard rubbers

The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to find the dependency the dissipated energy on the deformation energy. Based ...

Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Košina, Jan; Cibulka, Jan
Ústav termomechaniky, 2017

On Finite Element Approximation of Flow Induced Vibration of Elastic Structure
Valášek, J.; Sváček, P.; Horáček, Jaromír
2017 - anglický
In this paper the fluid-structure interaction problem is studied on a simplified model of the human vocal fold. The problem is mathematically described and the arbitrary Lagrangian-Eulerian method is applied in order to treat the time dependent computational domain. The viscous incompressible fluid flow and linear elasticity models are considered. The fluid flow and the motion of elastic body is approximated with the aid of fininite element method. An attention is paid to the applied stabilization technique. The whole algorithm is implemented in an in-house developed solver. Numerical results are presented and the influence of different inlet boundary conditions is discused. Klíčová slova: stabilized finite element method; 2D Navier-Stokes equations; vocal folds; aeroelasticity Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
On Finite Element Approximation of Flow Induced Vibration of Elastic Structure

In this paper the fluid-structure interaction problem is studied on a simplified model of the human vocal fold. The problem is mathematically described and the arbitrary Lagrangian-Eulerian method is ...

Valášek, J.; Sváček, P.; Horáček, Jaromír
Ústav termomechaniky, 2017

Creepová analýza VT vnitřního tělesa DSPWR – kontaktní úloha
Kopačka, Ján; Masák, Jan; Gabriel, Dušan; Plešek, Jiří
2017 - český
Zpráva shrnuje výsledky III. etapy rešení creepové analýzy vysokotlakého vnitrního telesa Doosan Škoda Power. Je provedena analýza vysokotlakého vnitrního VT telesa s respektováním kontaktních okrajových podmínek v delicí rovine a použitím komplexního creepového materiálového modelu. Výsledky kontaktní analýzy v programu PMD jsou porovnány s namerenými hodnotami a též srovnány s programem ANSYS, kde byl použit Nortonuv-Baileyuv model creepu. The report summarizes results of the 3rd stage of the creep analysis of Doosan Škoda Power high-pressure inner casing. An analysis of the high-pressure inner casing is carried out with respect to the contact boundary conditions in the division plane and the use of a complex creep material model. The results of the PMD contact analysis are compared to the measured values and also compared with the ANSYS program where the Norton-Bailey model of creep was used. Klíčová slova: creep analysis; contact analysis; turbine casing Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Creepová analýza VT vnitřního tělesa DSPWR – kontaktní úloha

Zpráva shrnuje výsledky III. etapy rešení creepové analýzy vysokotlakého vnitrního telesa Doosan Škoda Power. Je provedena analýza vysokotlakého vnitrního VT telesa s respektováním kontaktních ...

Kopačka, Ján; Masák, Jan; Gabriel, Dušan; Plešek, Jiří
Ústav termomechaniky, 2017

Greep analysis of-piece of the steam distributor
Gabriel, Dušan; Masák, Jan; Plešek, Jiří
2017 - anglický
The finite element analysis of the steam distributor of the CHEMOPETROL heating plant T200 was analyzed under creep conditions. Material properties were described by the probabilistic exponential model with damage. The purpose of the analysis was to compare the original version and the proposed design modification applied to one of T-pieces of the distributor when the original contact algorithm was employed to simulate the interaction between the collar and the pipe. Klíčová slova: creep analysis; T-piece of the steam distributor; FEM Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Greep analysis of-piece of the steam distributor

The finite element analysis of the steam distributor of the CHEMOPETROL heating plant T200 was analyzed under creep conditions. Material properties were described by the probabilistic exponential ...

Gabriel, Dušan; Masák, Jan; Plešek, Jiří
Ústav termomechaniky, 2017

Dissipated energy of hard rubbers at dynamic torsional finite straining
Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Cibulka, Jan; Košina, Jan
2017 - anglický
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to find the dependency the dissipated energy on the deformation energy. Based on the results of an experiment, a function of dissipation energy of hard rubbers for finite strains using the theory hyperelasticity was proposed herein analogically as a prportional damping for elastic theory. Samples of hard rubber of different hardness (EPDM, Silcone) were dynamically tested on the developed torsional test-rig at different frequencies, amplitudes. First the Mooney Rivlin model (MRM) for a shear case of loading was analytically developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. These constants were used to obtain the deformation energy of the MRM models. The coefficients of hyperelastic proportional damping relating a dissipated energy to a strain energy were evaluated for tested rubbers on the basis of experimental results. Klíčová slova: hard rubber; torsion vibration; large deformation Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Dissipated energy of hard rubbers at dynamic torsional finite straining

The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to find the dependency the dissipated energy on the deformation energy. Based ...

Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Cibulka, Jan; Košina, Jan
Ústav termomechaniky, 2017

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