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Suspension flow modeling
Hideghéty, Attila ; Koutný, Luděk (referee) ; Rudolf, Pavel (advisor)
Diplomová práce se zabývá prouděním v hydrocyklónu. Hydrocyklón je separační stroj, kterým slouží k oddělování pevných částice z kapaliny (nejčastěji z vody). Díky tangenciálnímu vstupu do zařízení nastává silné vířivé proudění, které způsobuje přisávání vzduchu přes horní a dolní výtok. Toto vzduchové jádro hraje důležitou roli v separaci částic. Výpočty jsou provedeny pomoci CFD.
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Hydraulic characteristics of the cavitation nozzles
Gríger, Milan ; Habán, Vladimír (referee) ; Rudolf, Pavel (advisor)
The main goal of this thesis is the examination of hydraulic characteristics for different cavity nozzles, influence of liquid rotation and visualization of cavitating flow. Thesis is divided into two parts, theoretical and practical. Theoretical part deals with the description of cavity - creation, development and its extinction. This part also contains description of vortex flow and basic vertex models. Practical part compares nozzles performance experimentally. The aim of experiment was to measure hydraulic characteristics and their comparison. Jet performance was judged using visualizations and measured data was processed in Microsoft Excel and Parametr.
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High-specific speed hydraulic turbine
Holub, Jiří ; Haluza, Miloslav (referee) ; Rudolf, Pavel (advisor)
The aim of this thesis is to design a geometry of runner of high specific speed turbine which is supposed to provide the maximum flow rate of the turbine while achieving a relatively high hydraulic efficiency. New design is based on the analysis of the hydraulic characteristics of three previous design sof very hiát specific speed turbines. The actual hydraulic pdesign of the turbine runner is based on CFD computations. Special software tools like BladeGen and TurboGrid were used for petting up the geometry and mesh for the very first time at Kaplan Department of Fluid Engineering.
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Cavitating flow in converging-diverging nozzle
Hlaváček, David ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
The master´s thesis deals with the flow induced by rotation of cavitating fluid in converging-diverging nozzle, which simulates the vortex rope in impeller of water turbines. Measurement is performed on an experimental circuit in laboratory. Results from experimental measurements are compared with CFD simulation of single and two-phase flow. The main focus is to compare the difference of hydraulic losses and shapes of cavitating structures identified in the experiment and in the simulation.
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Water column separation under hydraulic turbine runner during unsteady operating regimes.
Vašek, Lubomír ; Rudolf, Pavel (referee) ; Habán, Vladimír (advisor)
In this diploma thesis called Water column separation under the hydraulic turbine runner during unsteady operating regimes are solved the pressure pulsations of the reverse water hamer. In the thesis is deduced a mathematical relationship of elaboration the numerice model which is based on equations of continuity and equations of forces equilibrium. Numerical model is created in MS Excel uses for computation the numerical method Lax-Wendrof that allows consideration of variable sound speed as function of static pressure and allows variable lenght step in computation domain. Reverse water hammer is in the thesis solved with consideration of rotating flow behind shut-off valve, where we expect forming of vortex rope. This situation can be applied on the closing water turbine which has vertex rope under turbine runner. Specifically for this thesis was carried out the experiment of the reverse water hammer. Constants going into numerical solution are optimalized with using experiment and pressure pulsation are compared between numerical solution and experiment.
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Installations in the draft tube of the swirl turbine
Kilian, Ondřej ; Rudolf, Pavel (referee) ; Haluza, Miloslav (advisor)
Diploma thesis deals with design and exploration of installation in the draft tube of the swirl turbine. Use of the draft tube is defined in the first part, with illustration of energetical gain and efficiency of draft tube. Further the suitable shape of draft tube is studied by CFD computing. Design, research and evaluation of installation in the draft tube are solved in the main part.
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Eigenmodes of the swirling flow
Jízdný, Martin ; Pochylý, František (referee) ; Rudolf, Pavel (advisor)
This thesis deals with study of dynamics of the swirling flow. The swirling flow occurs frequently in hydraulic machinery (e.g., vortex rope in draft tube of the hydraulic turbine) and often influences operation of these machines. For this reason, sufficient knowledge regarding this characteristic flow is necessary for subsequent improvement of hydraulic machines. The theoretical part of this thesis contains description of flow instabilities and their manifestations, notably Kármán vortex street and vortex rope. In the next part, two methods are applied to these two transient flows in order to identify their specific dynamic properties. The first method, Fourier transform, enables to find frequencies of transient flow. The second method, proper orthogonal decomposition (POD), enables to identify planar or spatial eigenmodes of a specific swirling flow. Proper orthogonal decomposition is used in this thesis to identify planar eigenmodes of Kármán vortex street and spatial eigenmodes of vortex rope.
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Flow structure and energy transformation in an elbow draft tube
Štefan, David ; Skoták, Aleš (referee) ; Rudolf, Pavel (advisor)
Draft tube is very important part of hydraulic turbines. Only optimum work together with turbine can bring highest performance of this machine set. Hence it is necessary to deal with character of flow in the draft tube for different operating conditions. Efficiency of the draft tube depends on many phenomena of flow. Observing these phenomena and finding their relation with energetic transformation in the draft tube is a suitable tool to judge quality of draft tube performance. Incorrect design of the draft tube can sometimes cause lower efficiency of whole machine set. The goal of this thesis is finding the main reasons causing draft tube efficiency drop for given operating conditions.
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