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Design of low-subsonic blade cascade model for aero-structural dynamic testing
Pešek, Luděk ; Hála, Jindřich ; Šulc, Petr ; Chládek, Štěpán ; Bula, Vítězslav ; Uruba, Václav ; Cibulka, Jan
Low-subsonic blade cascade model for aerodynamic testing was design in the Institute. The aim is to study the flow dynamics and flutter phenomenon in the cascade with moving blade profiles. The numerical calculations of two proposed cascades were performed for analysis of influence of stagger angle, incident angle of flow and inter-blade phase angles of the relative movement of blades. The results of numerical simulations of fluid dynamics of non-stationary flow both as viscid and non-viscid are presented. Futhermore the solution of the physical model of the designed cascade including excitation of profiles, measuring of the profile displacement and aerodynamic forces are described.
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Measurement, analysis and identification of complex modulus of elasticity of a ruber segment pressed onto a rubber-damped whell
Pešek, Luděk ; Šulc, Petr ; Bula, Vítězslav ; Cibulka, Jan
The aim of this study was to measure, analyze and identify the complex modulus of elasticity of rubber segments pressed onto the "Hong Kong" rubber-damped railway wheels in relation to the deformation nodes of wheel vibrations. The main goal was to improve the description of the frequency dependence of the material constants of the rubber segments pressed between the disk and the rim with large pre-stress (about 20%) during the production of the rubber-damped wheel. The solution consists of two parts: a) the modal analysis of the railway wheel, b) the identification of the frequency dependence of Youngś modulus and the loss factor of the wheel rubber by the finite element method. The obtained results are in good accordance with the behavior of hard synthetic rubber.
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Modelling Flow Processes in Turbomachines using Wind Tunnels
Šafařík, Pavel ; Luxa, Martin ; Šimurda, David
The contribution is concerned with process of preparing and executing high speed aerodynamic research on models of turbomachinery flow parts. Results of research on flow past blade cascades representing sections of turbomachinery bladings are discussed. Employed optical methods of measurement provide basis for descriptions of high speed flow field structures and also for quantification of flowfield parameters. Traversing with five hole conical probe in exit flow field provide aerodynamic parameters important for design and further development of turbomachinery. Presented results have been selected from large database containing data on modelling flow parts of large output steam turbine last stages, radial compressor inducer and research on flow past compressor cascade. Results of research on flow past turbomachinery flow parts at off design conditions of operation are also presented and discussed.
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Research of pressure pulsations and vibration in the turbine 1,000 MW
Procházka, Pavel ; Vaněk, František ; Sadílek, J.
The paper describes the methods and equipment used in experimental research of pressure pulsations with simultaneous measurement of vibration of the stator and blades of the third moving wheel in the turbine 1,000 MW at the nuclear power plant Temelín in 2012. The aim of this work was to find links and possible sources of blade vibration during the turbine start-up. The observed phenomena are analyzed, focusing on the causes of blade vibrations in the stage L-1.
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Extended musical teaching in primary school
ŠTRUPLOVÁ BARTOŠKOVÁ, Magdalena
The thesis called "Extended musical teaching in primary school" addresses the initial idea of the author, professor Ladislav Daniel, since itś creation till its development in the last 45 elapsed years of its continuation in the Czech Republic. Based on this method this experimental research has taken place. This research will focus specifically on The 2nd primary school in Jindřichův Hradec where extended musical teaching has been in progress. The purpose of this activity is to find out how this school has dealt with extended teaching (the reason for its foundation, difficult situations during teaching, where is the musical education leading) and if this way of educating is comparable to professor Danielś method.
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Issues in the research of visual space perception: The geometry of visual space, relationship between the spatial descriptors, and the metric vs. ordinal data
Šimeček, Michal ; Šikl, Radovan
In the article, the authors summarize the main results of their research activity in the field of visual space perception. In the particular experimental projects, they focused on the relationship between the partial spatial descriptors in the process of forming the complex three-dimensional percept. Also, the geometry of the optical space was dealt in with respect to the Euclidean geometry of the physical space. The principle finding concerns the notion of anisotropic curvature of visual space. Finally, the question of plausibility of experiments requiring the perceptual judgements as expressed in metrical units (Euclidean tasks) was raised. The reason for this approach being used is to gather data directly comparable with the physical properties of space. On the other hand, in Euclidean tasks, the ecological validity of knowledge gained is inevitably limited and the danger of intrusion of nonperceptual factors is pervasive.
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Evaluation of vibrational eigenfrequencies and eigenmodes and loss factor for monoblock rail wheel
Pešek, Luděk ; Veselý, Jan
The aim of this research was evaluated experimentally eigenfrequencies, eigenmodes and loss factors for the monoblock rail wheel in two options: a) without acoustic damping disc, b) with acoustic damping disk. Excitation was realized by an electrodynamic vibrator with different levels of excitation and by hammer. The raill wheel was forced on a wheel set placed on a special frame. Frequency range of modal analysis was up to 6400Hz with step 0.25Hz. The measurement and analysis was performed for all identifiable eigenfrequencies with emphasis on eigenmodes having from two up seven node radials without node cirles. Pro determination of eigenfrequencies and loss factors corresponding eigenmodes the modal analysis was carried out for all options of the damping disk.
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Design, development and realization of vibration measurement on riding metro wheel with and without add-on damper
Pešek, Luděk ; Vaněk, František ; Vaněk, Petr ; Cibulka, Jan
The aim of this research was design, developement and realization of vibration measurement (acceleration) of the riding metro wheel with and without add-on damper. The radiotelemetric method with four measurement channels was used for the operational measurement of vibration and noise. The solution was devided into four steps a) design and devolopement, laboratory tests and production of modified radiotelemtric equipment for measurement on the tram wheel; b) installation of the sensors and radiotelemetric equipment; c) realization of vibration operational measurement; d) measured data processing. In the report there is described a methodology of measurement and dynamic analysis used for comparision of the wheel with and withoud add-on dampers. The different riding regimes and tracks, i.e. direct, bow , were analysed. The third octave spectra nd amplitude time-frequency characteristics of accelerations and acoustic pressure were evaluated from the digital recorded time signals.
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Design, development and realization of vibration measurement on riding tram wheel with and without add-on damper
Pešek, Luděk ; Veselý, Jan ; Vaněk, František ; Cibulka, Jan ; Bula, Vítězslav
The aim of this research was design, developement and realization of vibration measurement (acceleration) of the riding wheel with and without add-on damper. The solution was devided into four steps a) design and devolopement, laboratory tests and production of modified radiotelemtric equipment for measurement on the tram wheel; b) installation of the sensors and radiotelemetric equipment; c) realization of vibration measurement of the carriage KT8D5; d) measured data processing. In the report there is described a methodology of measurement and dynamic analysis used for comparision of composed rim-rubber-disk wheel with and withoud add-on dampers. The different riding regimes and tracks, i.e. direct, bow and cross, were analysed.
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