National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Analysis of dynamic properties of pneumatic actuator
Hrivňák, Ján ; Žatko, Miroslav (referee) ; Malenovský, Eduard (advisor)
This thesis deas with dynamic analysis of pneumatic actuator which is used as regulation mechanis of turbochargers with Variable Nozzle Turbine (VNT) technology. The first part of work is focused on experimental modeling which goal is obtaining Frequency Response Function on specify frequency range by Frequency Response Function Analysis – FRFA. Dominant vibrations of pneumatic actuator active parts is expected on this specify frequency range. Results of experimental modeling will be used for gaining input parameters for numerical computation as well. The second part deal with Pre-Stressed Modal Analysis and subsequently Harmonic analysis. Obtained results with numerical and experimental analysis will be compared. This part of diploma thesis is solved in programmatic environment ANSYS Workbench.
Fluid-Structure Interaction between Structural Components of Hydraulic Turbine and Fluid Flow
Havlásek, Michal ; Malenovský, Eduard (referee) ; Vimmr, Jan (referee) ; Pochylý, František (advisor)
Tato dizertační práce se zabývá dvěma případy interakce tělesa s tekutinou (FSI). První z nich se zabývá analýzou vzájemné interakce mezi rotorem čerpadla a kapalinou uvnitř těsnící spáry. Vliv těsnící spáry na dynamiku celého stoje je popsán pomocí dynamických parametrů, které jsou také označovaný jako přídavné účinky. V současnosti používané modely těsnících spár používají pro stanovení dynamických parametrů řadu zjednodušujících předpokladů. V této práci je prezentováno pět různých analýz dynamických parametrů těsnící spáry čerpadla na okysličovadlo. Každá z těchto pěti analýz používá jinou míru zjednodušení výpočetního modelu. V případě největšího zjednodušení je modelován pouze objem kapaliny uvnitř těsnící spáry. Nejkomplexnější analýza pro stanovení dynamických parametrů těsnící spáry používá pro výpočet model celého čerpadla s excentrickou polohou rotoru. Druhá část této dizertační práce definuje novou metodu pro řešení interakce kapaliny s pružným tělesem. Tato metoda využívá řešení inverzního problému kmitání. Přímý problém kmitání, který je také označován jako problém vlastních hodnot, používá jako vstupy pro řešení matice hmotnosti, tuhosti a tlumení, které jsou dohromady označovány jako koeficientové matice, na základě kterých je v nejobecnějším případě stanovena Jordanovská matice a také modální matice pravostranných a levostranných vlastních vektorů. Při řešení inverzního problému kmitání jsou stanoveny koeficientové matice na základě Jordanovské matice a modálních matic pravostranných a levostranných vlastních vektorů. Existují dva případy inverzního problému kmitání. V případě, že jsou známy všechny vstupní vlastní čísla a vlastní vektory, pak se jedná o tzv. plný problém. Naopak v případě, že alespoň 1 mód kmitání soustavy není znám, tak se jedná o tzv. částečný problém. V této práci je prezentováno 5 algoritmů pro řešení inverzního problému v kmitání. Nicméně pro každý typ inverzního problému kmitání je prezentován jeden univerzální algoritmus. Algoritmus pro řešení plných problémů byl poprvé prezentován v roce 1979 Otakarem Daňkem. Algoritmy pro řešení částečných problémů, které jsou prezentovány v této práci, jsou vůbec prvními algoritmy pro řešení tohoto typu inverzního problému kmitání. Univerzální algoritmus pro řešení částečných problémů je označován jako algoritmus pro řešení částečných problémů s volbou doplňkových vlastních hodnot. Aplikace těchto dvou univerzálních algoritmů pro řešení inverzního problému kmitání pro případ plných i částečných problémů je ukázána na řešení dvou případů interakce pružného tělesa s kapalinou.
Computational Analysis Of Dynamic Behaviour Of Journal Bearings
Rak, Vladimír ; Kamenický, Ján (referee) ; Pochylý, František (referee) ; Zapoměl, Jaroslav (referee) ; Malenovský, Eduard (advisor)
This work deals with computational modelling of static and dynamic analyses of journal bearings, with analyses of stability of oil-film motion and analyses of response of the rotor assemblies. At our workplace a new theoretical approach to the modelling of the static and dynamic behaviour of the rigid rotating body in liquid is used. The approach is based on the application of the Navier-Stokes motion eq., equation of continuity and boundary conditions eqs. It is possible to separate the motion of the rigid body and liquid from each other using suitable transformation relations and then it is also possible to separate the stationary and nonstationary motions from each other. A method of control volumes is used for these analyses. The real Bézier body is used for the description of the geometrical configuration and also for the approximation of velocity and pressure functions. Combined the ALE (Arbitrary Lagrange-Euler) method is used, because it´s necessary to generate a new net (to perform new meshing) for a change of the shaft position. The additional effects of the liquid (additional mass, stiffness and damping), which we solved in dynamic analysis, are the function of the single parameter only – the shaft-centre position. There is a large advantage in comparison with the standard approach, which is based on application of the Reynolds liquid eq. Author solving the models of the long and short journal bearing with different geometry, especially the elliptical and cylindrical bearings, with incompressible and compressible journal bearing liquid. If the journal bearing problem is solved, it is possible to include the additional effect of the liquid to the right side of the motion equation of a model rotor assembly. Author analyze a model rotor assemblies with two degrees of freedom, which is supported inside of the two journal bearings on the ends of the rotor (Jeffcott rotor assembly). Author modelling and solveing a response of the model rotor assembly on the forced steady-state vibrations, which was actuating by the unbalanced matter.
Dynamic behavior od rotor dynamics system vibrating in a liquid
Kučera, Martin ; Pohanka, Lukáš (referee) ; Malenovský, Eduard (advisor)
This thesis deals with dynamic behavior of rotor dynamics system vibrating in a liquid. Work is factually oriented on influence of the liquid to natural frequences of rotor of vortex turbine. There is described the creation of geometric and computational model of the system and the results of natural frequences and damping in dependence on environment are presen-ted. There are compared variations in natural frequences of the rotor system, which are caused of the interaction of the various level of the water environment. The step of integration are tested and compared for choise solving method. Problem is solved by computational simulation in commercial software ANSYS 11.0 There is used software tools Multiphysics/FSI.
Dynamic behavior od rotor dynamics stystem vibrating in a liquid
Chlud, Michal ; Pochylý, František (referee) ; Malenovský, Eduard (advisor)
This thesis deals with dynamic behavior of swirl turbine vibrating in a liquid. Primarily is studied decrease of natural frequencies of rotor due the interaction with fluid environment, namely for different levels of submerged rotor in fluid. After that follows the detection of natural frequencies of swirl turbine in operating speed. The problem is solved by computational modeling in ANSYS system. For this solution is used acoustic elements method. The results are compared with experiment.
New Types of Boundary Conditions for Solution of Fluid Structure Interaction Problems and their Implementation in Commercial Simulation Software
Pohanka, Lukáš ; Pochylý, František (referee) ; Zapoměl, Jaroslav (referee) ; Rudolf, Pavel (referee) ; Malenovský, Eduard (advisor)
New approach for computational modeling of the dynamic behavior of elastic body immersed in incompressible viscous stagnant fluid is described in this work. It is based on determination of added effects (added mass and added damping). This effects are inserted into computational model and it replace influence of the fluid. Commonly used commercial computational software may be used. Approach is based on assumption appropriate for the linear flow. Two pressure field are determined. One for movement of the unite acceleration of the fluid boundary and the second for unite velocity. Nonlinear model (Navier-Stokes equation in ALE form) had to be used for determination of the added damping, hence results are valid only for pre-selected amplitude of vibration.
Numerical solutions of examples from kinematics and dynamics
Zemánek, Tomáš ; Malenovský, Eduard (referee) ; Pellant, Karel (advisor)
The application of special mathematics softwares for numerical solution of examples from mechanics is performed. The submitted examples are from kinematics and dynamics, the relationship with other subjects taught at FME is evident.
Computational analysis the state of stress of turbine blade
Klement, Jan ; Žatko, Miroslav (referee) ; Malenovský, Eduard (advisor)
This diploma thesis continues to the Ing. Damborský work and deals with strain-stress and dynamic analysis of the steam turbine blade. This blade is part of the last row of low pressure level of steam turbine. Computational analysis has been performed in first part using FEM. After that follows a modal analysis for the blade without residual stress as well as for the blade affected by heat treatment. Main goal is to obtain whether the state of stress is in the crack initiation area is influenced by thermal treatment. This problem was solved by computational simulation in commercial software Ansys 11.0.
Frequency modal analysis of blade package of steam turbine
Přikryl, František ; Skalka, Petr (referee) ; Malenovský, Eduard (advisor)
This thesis deals with comparison the results of the frequency modal analysis of blade package of steam turbine with stiffening or damping bounding elements. Computational model was created through the finite element method, using cyclical symmetry. The results were compared with experimental analysis and analysis in VIPACK programme. Thesis also contains creating the solid blade model, using the reverse engineering.
Physical Quantities Measurement of the Rotating Parts
Štorek, Pavel ; Malenovský, Eduard (referee) ; Pozdník, Jaroslav (referee) ; Veselka, František (advisor)
This work is dedicated to small distance contact-less measurement. Especially the surface detection of the commutator or collector of the electrical machines was described. The probes utilising the induction principle of the distance measurement have been developed. The part of the work described the history of the induction distances sensing in FEEC BUT and the using of the induction principle in the industry small distances sensing nowadays. The paper concretely determines the possibilities of the small distances measurement using mentioned probes. The sensitivity for different materials was investigated and the error of the measurement for different measuring object was investigated, too. The effects, that could affected the measurement error, were described in the work. The contribution of the each effect for the total measuring error was specified. Next part is including the description of the measuring workstation and of the hardware and software. At the end the verification of the measuring principle and measuring workstation is presented. The verification has been made on three different commutator types. The verification results are in the conclusion.

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