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Frequency analysis of the blades of the steam turbine impeller
Krejčí, Jaroslav ; Chromek, Lukáš (referee) ; Lošák, Petr (advisor)
The master thesis deals with modal analysis of the blade of the steam turbine impeller. This analysis is made to find the frequency response of the blade in order to predict the dangerous speeds of the steam turbine. At first the problem situation is described. Than follows the research study which is focused on steam turbines and especially on the rotor dynamic systems and the way to ascertain the modal parameters of the dynamic system by experiment. After that the solution of the problem is performed by computational modelling. The results of the computation are analyzed in detail for different variations of the blade length by Campbell diagram. A graph showing dependency between dangerous speeds of the turbine and the blade length is made out of the results. Then the results are verified by experiment and the coefficients of proportional damping are specified. In conclusion the optimal variation of the blade length for the given operational state is determined.
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Dynamic Behavior of Laval Rotor
Nováková, Naděžda ; Hlavoň, Pavel (referee) ; Malenovský, Eduard (advisor)
The aim of this bachebor’s thesis is to specify self-frequency of model rotor system and verify that the system may be considered as Laval rotor. The natural frequency is obtained by calculating from the known relations for the circular rotor vibration. Verify that the model rotor system can be Laval rotor, is performed by using experimental measurements, which is determined in shaft deflection trajectory during gradually increasing speed. The measured values are then processed in program MATLAB. The results are compared with theory of Laval rotor
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Design of computational algorithm of electric machine rotor with respect to stress-strain relationships and critical speed
Pařízek, Daniel ; Lošák, Petr (referee) ; Vlach, Radek (advisor)
The Master's thesis deals with the mechanical design of electric machine rotor. Within the first two chapters of the practical part of the thesis two simplified computational models of the rotor (level 1 models) are compiled. Specifically, the model of flexible rotor mounted on rigid supports and model of rigid rotor mounted on flexible supports. The essence of these computational models lies in solvability using simple equations. Using these models can save time when constructing a pre-design of the rotor geometry. The following chapter is devoted to comparing different approaches to computational modeling of rotor using FEM. A predetermined preliminary design of a high-speed massive rotor is investigated. Computational models of different levels at stress-strain analysis and modal analysis are presented. It also includes a suggestion on how to proceed effectively in a given analysis.
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Calculation of the dynamic behavior of the rotor using the method of transfer matrices
Kratochvíl, Filip ; Hrstka, Miroslav (referee) ; Lošák, Petr (advisor)
The master‘s thesis deals with the modelling of a rotor using the transfer matrix method and the displacement method. Specifically, it addresses the response to static loading, the first natural bending oscillation shape and the response to imbalance. The focus of the review is on the transfer matrix method and its practical applications in various parts of dynamics. The method of rotor modelling and the various elements used for this purpose are also described. The first practical part focuses on the static response of the rotor to self-weight and external loads. This is solved based on the transfer matrix method. The next part deals with finding the rotor's natural speed based on the transfer matrix method and the displacement method. For this purpose, two different approaches have been used depending on the method. For the transfer matrix method, the interval halving approach was chosen and for the displacement method, the eigenvalue problem was solved. The last practical part is the solution of the response to imbalance. This was done based on the displacement method. At the end of the thesis, a control example is performed where the derived solution is compared with the solution using the finite element method.
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Pilový kotouč v procesu podélného řezání materiálů na bázi dřeva
Veselý, Přemysl
In this dissertation thesis there is listed characteristics of circular saw blades, their distribution, influence of construction adjustments on final behavior of blade in the process of machining, problematic of oscillation of blades a mutual interaction among quality of machined surface, noise and dust. The thesis covers the problems of oscillation of circular saw blades as when idling and operating - the cutting process; and by the use of three circular saw blades with different construction modifications. These aforementioned construction measures are also compared to each other due to the implementation of standard construction saw blades not only from the perspective of oscillation, but also from the perspective of the roughness of the machined surface and the analysis of wood waste generated during cutting and noise. In the theoretical part there is an analysis of available literature and scientific theses. It outlines the particular publications devoted to methods of determining the shapes of oscillation, determining critical, resonant and recommended speed, blade constructions, including possible modifications, the theory of cutting saw blades including determining the size and shape of the splints and the effects of noise on the work environment. An important part of this work is methodology involving direct measurements for detection of unstable states of discs (resonance and critical speed. In this section it is further evaluated measuring of the oscillation of the test saw blade and verification of the proposed methodology with a different and practiced, commonly known method, so called cold shapes: The author also seeks to explore and determine the effect of different tooth pitch and method of execution of slots along with soundproofing grooves on noise levels, the resulting quality of the machined surface of various wood. The generated waste is then analyzed for splitting wood particles in particular size group with the percentage of each chip. The results of the experiment are in discussion confronted with the available scientific theses, taking into account with normal operating conditions, of which the conclusion is drawn.
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Analysis of transfer matrix method using for calculation of electrical machines rotor with influence of magnetic pull
Tobiáš, Jan ; Majer, Zdeněk (referee) ; Vlach, Radek (advisor)
This master thesis is dealing with modeling of the rotor system based on the numerical transfer matrix calculations. This method is suitable for fast analysis of beam bodies to observe the resulting deflection and critical speed in regard to the initial circumstances. The bearing stiffness is a significant input factor that affects the outcomes of the analysis, especially the critical speed the rotor system. First of all,the available approaches to analyze the bended beam bodies are discussed focused on explanation of the transfer matrix algorithm. After that, the approach to estimate the bearing stiffness based on the Hertz contact theory is presented. Further, a brief explanation is given about the heat arising in the rotor bearings. The following chapters are focused on description of the software solver for rotor system analysis based on the transfer matrix method, considering the bearing stiffness estimation based on Hertz contact theory, with possible calculations of the induced bearing heat losses. In the end, the practical use of the developed software is presented with the analysis of the obtained results of the rotor deflection, critical speed, and bearing power loss. There is also discussed a comparison of the different bearing stiffness estimation with the impact to the computation outcomes, especially on the rotor critical speed, followed by comparison conclusion implementation into rotor system analysis.
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Analysis of the rotor packet prestress on the rotor critical speed
Lekeš, Filip ; Huzlík, Rostislav (referee) ; Lošák, Petr (advisor)
The presented diploma thesis deals with the modeling of the rotor packet in dynamic calculations and analysis of the influence of the packing pressing force on the critical speed of the electric motor. The thesis can be divided into three main parts. The first part discusses the current level of rotor packet modeling in dynamic calculations and also deals with analytical theories for subsequent experimental tests. The second part describes the implementation of two experiments to determine the equivalent modulus of elasticity. The first experiment is a four-point bending test and the second is an experimental modal analysis. The third part is used for comparing the results obtained from experimental tests and describes the calculation of the critical speed of the rotor package pressed on the shaft by the finite element method.
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Design of high speed permanent magnet synchronous machine
Přibyl, Daniel ; Knebl, Ladislav (referee) ; Ondrůšek, Čestmír (advisor)
Bachelor's thesis is focused on problematic of synchronous machines with permanent magnets. In this thesis is described the principle of function and design solution of the machine. Furthermore it deals with stator winding, possibility of placing magnets on the rotor and used types of permanent magnets. In the part of solution of the assignment of work is made design of synchronous machine with permanent magnets with output 1,5 MW and rated speed 15000 rpm. The machine is designed with inner rotor and magnets placed on surface. The solution includes design of dimensions of stator including design of slot, design of winding and design of permanent magnet. The whole analytical design was finally compared with the results of the analysis in the RMxprt program. For machine was calculated 2D magnetic field by finite element method in Ansys Maxwell. Finally was calculated critical speed.
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Design of computational algorithm of electric machine rotor with respect to stress-strain relationships and critical speed
Pařízek, Daniel ; Lošák, Petr (referee) ; Vlach, Radek (advisor)
The Master's thesis deals with the mechanical design of electric machine rotor. Within the first two chapters of the practical part of the thesis two simplified computational models of the rotor (level 1 models) are compiled. Specifically, the model of flexible rotor mounted on rigid supports and model of rigid rotor mounted on flexible supports. The essence of these computational models lies in solvability using simple equations. Using these models can save time when constructing a pre-design of the rotor geometry. The following chapter is devoted to comparing different approaches to computational modeling of rotor using FEM. A predetermined preliminary design of a high-speed massive rotor is investigated. Computational models of different levels at stress-strain analysis and modal analysis are presented. It also includes a suggestion on how to proceed effectively in a given analysis.
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