National Repository of Grey Literature 74 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Numerical solution of the cavitation bubble dynamics
Münster, Filip ; Himr, Daniel (referee) ; Rudolf, Pavel (advisor)
This thesis deals with the numerical solution of cavitation bubble dynamics and with cyanobacteria gas vesicle behaviour. A program for the numerical calculation of bubble dynamics is created using the Rayleigh-Plesset equation and its modifications. Subsequently, bubbles of different sizes are investigated during acoustic cavitation with various driving frequencies. Furthermore, a model for hydrodynamic cavitation is created. The model combines CFD computation of flow in the Venturi nozzle with the cavitation bubble dynamics calculation. The last part of the work is dedicated to cyanobacteria gas vesicle behaviour in a variable pressure field and during passage through the Venturi nozzle.
Computational simulation of air flow in a gas burner
Waloszek, Jan ; Rudolf, Pavel (referee) ; Vondál, Jiří (advisor)
This work is focused on computational modelling of a flow in a burner. The main objective is to provide a complex comparison of the results obtained through several approaches to modeling, on different computational grids and also using different turbulence models. Experimental measurement data are used for validation. Numerically obtained data are compared to each other and to experimental data. The method of Proper-Orthogonal Decomposition is also applied on the calculated data. The greatest benefit of this work is providing a wider view on the swirling flow modeling in burners and the results obtained here will help to better understand the behavior of stated models for tasks of this kind and their potential for modelling combustion in furnaces.
Mutual interaction of magnetic field and cavitating flow
Harazin, Přemysl ; Štigler, Jaroslav (referee) ; Rudolf, Pavel (advisor)
Presented work consists of research and experimental part. Main focus of the research part is on mutual interaction between magnetic field and water and between magnetic field and cavitating flow. Prediction of the result is almost impossible, because the opinions on the effects differ, sometimes even go against each other. Experimental part consisted of three trials with permanent magnets. Electromagnetic probe was employed for measuring of the voltage. It appears, that magnetic field affects the cavitation, because in all of the trials the measured voltage changed after the switch from non-cavitating to cavitating flow. The change of the voltage was not great enough, thus application of this phenomenon in practice cannot be recommended.
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.
Experimental investigation of the pumps for cryogenic proppellants of the rocket fuel systems
Šuráň, David ; Rudolf, Pavel (referee) ; Kozák, Jiří (advisor)
This bachelor’s thesis deals with the pumping of cryogenic substances. The main objective is a research of experimental investigation of rocket turbopumps. Specific experiments, their purposes, processes and final results including the detailed description of the test rigs are listed. Originally, the work was aimed to pumping of the liquid oxygen (LOX), but it turned out that liquid oxygen simulants are used extensively during the experimental testing. The essential conditions for comparing those substances are stated. Major references were obtained from the experimental investigation technical reports and scientific articles. The rest of the work describes basics of hydrodynamics, pumps and their parameters, cavitation, inducers, rocket combustion cycles and liquid propellants. Finally, author designed a test rig for cryogenic substances pumping.
Hybrid systems for energy storage
Tománek, Ladislav ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
Hybrid energy storage system, energy storage system, renewable energy sources
Cavitation heater
Rovder, Juraj ; Závorka, Dalibor (referee) ; Rudolf, Pavel (advisor)
This report is considering an equipment that is using cavitation to heat water. The theoretical part explains basic principles of its function and different types of such device. Following chapters describe a construction of used heater and an experiment carried out on this device. The results of the experiment are collected and evaluated. The final part of the thesis contains suggested adjustments of the given cavitation heater.
Study of Surface Vortex Behaviour
Illík, Jakub ; Rudolf, Pavel (referee) ; Štigler, Jaroslav (advisor)
This bachelor thesis studies surface vortex and its time evolution. The theoretical part introduces an elementary set of equations used to describe vortex motion. The experimental part focuses mainly on defining the shape of surface vortex in enclosed space. A special program to process recorded images was developed in order to detect a part of the vortex. The entire surface profile is subsequently determined by fitting with curve of Cauchy probability distribution.
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.
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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See also: similar author names
1 Rudolf, Patrik
1 Rudolf, Petr
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