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Dynamics of cavitating flow behind the orifice
Kubina, Dávid ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
Cavitating flow through five perforated plates with different number of holes with preserved constant flow cross-section area in sum were experimentally examined. Dynamic characteristics such as dependence of pressure amplitudes and dominant frequencies on cavitation number in all regimes of cavitating flow: incipient cavitation, partial cavitation, fully developed cavitation and supercavitation are obtained. For determination of dominant frequencies several pressure transducers in two regimes of measurement were used. Results were validated with frequency spectra obtained from picture analysis based on high-speed camera records.
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Cavitating flow in perforated disc
Kubina, Dávid ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
The main goal of this bachelor thesis is to measure hydraulic characteristics of five round plates perforated with several circle orifices installed in the pipeline. The main condition was to preserve constant cross section of the holes in sum. Theoretical part of the thesis is focused on the basics of hydrodynamic cavitation and its practical usage in the industry. The experimental part of the paper deals with hydraulic characteristics of each shield perforated by varying number of orifices and also includes mutual comparison. Also high speed camera was used to detect the length of cavitation zone, although these results are not included in the conclusion of the thesis.
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Intake vortex modeling
Galuška, Jiří ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
This paper covers information research of basic design rules of industrial wet sumps. It describes mathematical models of vortices and method for their identification and visualization. Then the author focuses on CFD modeling of surface vortices with single phase and multiphase approach with Volume of Fluid method. Basic principles of multiphase CFD modelling in OpenFOAM and ANSYS Fluent are given. Description and benchmarking of suitable turbulence models is also present. The single phase and multiphase approach were successfully validated for a simple test case of bathtub surface vortex. Satisfactory agreement with experimental data was achieved. The accuracy and behavior of both solvers were compared between each other. This gives us useful tool for evaluation of inflow condition and danger of surface vortex occurrence in wet sumps. The acquired knowledges were used to design an experimental test case with geometry similar to industrial wet sump. A map of surface vortex occurrence has been created for different operating points. One of the operating point has been used for numerical simulation (both single phase and multiphase). Partial agreement with experimental observation has been achieved.
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Vortex rope for overload operation of Francis turbine
Kozák, Jiří ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
This master's thesis deals with CFD simulation of vortex rope in the elbow draft tube for overload operation of Francis turbine. The main objective of the thesis is to compare results of the CFD simulations of the original elbow draft tube with a derived straight cone draft tube considering volume and the shape of the cavitation region and dynamic flow characteristic. Results of the 3D simulations are also compared with axi-symmetric simulations, which reduce demands for computing time and power.
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Residential Building
Kozák, Jiří ; Němeček, Martin (referee) ; Sukopová, Dáša (advisor)
The Bachelor thesis deals with the processing of project documentation in the municipality Hutisko – Solanec. The project documentation and attachments are processed according to the current legislation, regulations and standards. The apartment building is situated on a parcel 362/1, which falls within the cadastral area of Hutisko – Solanec. The land is linked to the transport and technical infrastructure. This apartment building consists of four residential units. Each unit is designed for housing of 4 to 5 people. In the basement there are parking spaces for each apartment one. The ground area of the building is 308 square meters. The supporting structure is designed from the POROTHERM. The building is covered by an arched roof and the supporting structure consists of trusses. The apartment building is situated on a land slope and is embedded into it.
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Modeling two-phase bubble flow in microfluidics
Stehlík, Martin ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
The goal of submitted thesis is to perform a computer simulation of bubble creation in T-channel. In the first section of the paper, the theoretical applications of microfluidic bubble, micromachines and droplet formation are described. In the second part of the text, author uses cross flowing method for simulation od bubble creation. Furthermore, several settings in computer simulation software Fluent are mentioned. In addition, the influence of velocity at the T-channel inlet on surface tension and on bubble length is presented.
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Numerical simulation of the flow in the components of the hydraulic circuit
Broža, Martin ; Moravec, Prokop (referee) ; Kozák, Jiří (advisor)
The bachelor thesis is focused on the analysis of the possibilities Autodesk Simulation CFD with simulation of flow in the hydraulic circuit elements. It is a commercial program applied in solving water flow in the selected elements of the hydraulic circuit, in elbow, sudden enlargement and 90 degree sharp elbow. The obtained results are compared with experimental results from laboratory and the results obtained by the ANSYS FLUENT.
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