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Fatigue of selected water turbine components based on operating conditions
Androvič, Dominik ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
This diploma thesis deals with the determination of the service life of the journal bushings of the rotary bearing of the Kaplan turbine rotor blades. Due to the change in the way turbines are operated in recent years, a reduction in the service life of the journal bushings has been observed. The work aimed to create a model that would capture the effect of the turbine's operating mode on the service life of the sliding bushings. To simulate the behavior of the rotary bearing, the task was divided into hydraulic and mechanical parts. The hydraulic load of the Kaplan turbine blade was solved on a simplified model represented by a separate aerodynamic profile using CFD calculation. The mechanical part of the model was made up of a rotary pin mounted in journal bushings. The load of the bearing was derived from the CFD calculation and the FEM method with a contact task was used for the calculation. The basic service life of the selected type of journal bushings was derived from the foundation of an empirical relationship and contact pressures derived from the mechanical part of the model. Based on available experimental studies, our effort was to assess the influence of regulation by microdisplacements on the service life of the selected type of journal bushings or to correct the basic calculated service life.
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Design of a hydraulic system for long-distance water transport
Dobrovolný, Martin ; Kozubková, Milada (referee) ; Veselý, Jindřich (referee) ; Pochylý, František (advisor)
The Ph.D. thesis aims to design a hydraulic system for long-distance water transport by the serial connection of axial pumps. Specifically, there is presented an analysis of the axial centrifugal pump prototype, which was tested. The prototype has a specific design. An asynchronous electric motor with a hollow-shaft rotor is used. The pump's impeller is pressed into the hollow shaft. Some advantages follow from the design compared to common pumps and pumping stations. For example, it is possible to designate a compact design of a pump and lower pressure load of pipe, so the elastic material for the pipe's wall can be used. However, the main disadvantage of this design is related to the large rotating diameter, where the pump's seals are located. It leads to quite large mechanical losses on seals and in the context of relatively small hydraulic power also to small efficiency. Therefore one part of the Ph.D. thesis is focused on the pump's seal. The result of the work is a new design of the mechanical face seal with a spiral grooves. The seal was manufactured and subjected to the test. During the testing of the prototype axial pump, it was also revealed inappropriate hydraulic design. Therefore it was necessary to redesign the impeller and guide vanes of the pump.
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Modelled pressure pulsations in a fluid with the influence of a second viscosity
Dzjamko, Vladislav ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
The aim of this thesis is to determine the value of the speed of sound and the second dynamic viscosity of the fluid using numerical optimization of analytical model. Theoretically, the speed of sound and the second viscosity can be determined from three measured pressure waveforms in time along the length of the tube, while the speed of sound is traced to determine the correctness of the result. The thesis is divided into seven successive chapters. The first two define all the necessary concepts and the 1D analytical model used. The following chapters deal with the design of the experiment, data evaluation and numerical optimization of the search parameters in the frequency domain.The range of measured frequencies was from 1 kHz to 20,59 kHz. Einstein´s notation is used this this thesis. All graphs associated with the analytical model and the evaluation of the results are created in Matlab. The optimization functions fminsearch and lsqnonlin are used to evaluate the speed of sound and the second viscosity, however the fminsearch function overestimates the magnitude of the second viscosity. The thesis includes the calculation of the problem using Ansys and the subsequent comparison of all results.
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Diaphragm pump
Veselý, Přemysl ; Dobšáková, Lenka (referee) ; Pochylý, František (advisor)
The central goal of this work is to optimize the performance of the diaphragm pump so that it is able to operate under the given conditions, which at this moment do not meet. In the first part of the thesis, a basic research was created about diaphragm pumps, their simple division, inclusion in positive displacement pumps and the history of their development. In the following chapter, their construction and the meaning of each part of the machine was described in detail. Furthermore, several basic CFD calculations were carried out with the aim of locating the places with the greatest hydraulic losses. These analytical calculations were subsequently compared with practical experiments, from which the intention was derived. In the next point, based on these facts, several final adjustments were made with the aim of optimizing the performance of the entire system. After that, these design measures were further investigated and evaluated.
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Study of plunger pump with linear motor
Machát, Pavel ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
The aim of this thesis is an engineering design of plunger pump with linear motor. This type of pump is used especially for blood pumping in heart surgery. The theoretical part is focused on distribution of pumps, description of extracorporeal circuit and booster heart history. There are basic calculations derived, which describe plunger pump performance. Then varied designs of plunger pumps follows, which are differed in size, shape and application. Next part includes design of reverse valves and their CFD computation.
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Optimization of vortex pump
Šmíd, Pavel ; Bílek, Martin (referee) ; Pochylý, František (advisor)
The aim of this labor is to optimize the vortex pump. When this pump should find application on the field of health like human heart for extracorporeal circulation. We will deal with the analysis of shear stress in the pump and its size of it and consider the use nonwetting surfaces to reduce the shear stress values. All our analysis will be made by CFD calculations.
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Analysis of the Velocity and Pressure Fields of the Liquid Using Curvilinear Coordinates
Stejskal, Jiří ; Kozubková, Milada (referee) ; Kučera,, Radek (referee) ; Veselý, Jindřich (referee) ; Pochylý, František (advisor)
This work introduces a new method of hydraulic design of a centrifugal pump impeller. This method is based on a geometrical approach employing curvilinear coordinates that are used to formulate both the axisymmetrical flow model in a meridional shape and the final model of flow in a blade cascade taking into account the full 3D shape of the impeller blade. The solution to this model then directly provides the guidelines for shaping the impeller blade in order to suppress the secondary flows, thus increasing the impeller efficiency, which is demonstrated on a real impeller design case. The partial differential equations describing the flow in the blade cascade are numerically solved piecewise on each particular stream surface, which leads to a significant reduction of computational time.
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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.
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Monitoring of hydraulic machines using acoustic emissions
Závorka, Dalibor ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
The goal of this diploma thesis is to clarify possibilities of usage of acoustic emission as a hydraulic machinery diagnostics tool. Especially for exposing presence of ruptures or cracks in the parts of machine, assuming changes in acoustic exposure of the part during operation. This clarification is based on series of simple measured experiments, which consist of monitoring the bolt placed in fluid stream inside of a pipe. This bolt was preloaded against inner wall of pipe by appropriate tightening torque. This preload is supposed to simulate effects of the size of rupture. High preload simulates small rupture or none in object and respectively small preload is supposed to simulate big rupture. A group of pressure sensors and accelerometers measures experiments and their evaluations are processed by script created in software MATLAB. Outputs of this script are charts with effective values of respective sensors from the entire record split into individual frequency spectrums. These charts compare spectrums of each configuration to judge effects of parameters changes.
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