National Repository of Grey Literature 27 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Cavitation erosion mechanisms
Kotoulová, Helena ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
Předložená bakalářská práce se zabývá mechanismy kavitační eroze a je rozdělena na dvě hlavní části. Teoretická část popisuje princip kavitace, způsob jejího vzniku a především kolaps kavitačních bublin, který negativně ovlivňuje povrch obtékaného tělesa (např. na hydraulických strojích). Z tohoto důvodu je nutné podrobně studovat účinky kavitační eroze. Experimentální část je věnována testování kavitační eroze na kovových a plastových vzorcích vytisknutých na 3D tiskárně. Plastové vzorky byly srovnávány navzájem mezi sebou, kovové vzorky z 3D tiskárny se vzorky odlitými. O vlivu kavitační eroze na součásti vytisknuté na 3D tiskárně je stále ještě málo informací, i když se jedná o velmi progresivní a stále častěji používaný typ výroby.
Utilization of hydrodynamic cavitation for water treatment
Balko, Marek ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
This bachelor thesis deals with the observation of features of cavitation with emphasis on the hydrodynamical cavitation and its use for eliminating unwanted and badly degradable compounds from water. Thanks to high temperature and pressures that are present at a colapse of cavitation bubbles the water decomposes into highly reactive hydroxile radicals which are able to decompose even. This effect can furthermore be strenghtened by the use of advanced oxidation processes – AOP. The experimental part of thesis is dedicated to examining a ability of hydrodynamical cavitation degrade particular chemical substance from water, namely estrogen.
Solution of the unsteady motion of the body in the liquid flow
Zbavitel, Jan ; Kozák, Jiří (referee) ; Fialová, Simona (advisor)
The thesis deals with CFD solution of flow through mechanical heart valves. The opening part includes a research on the negative impacts of implantation of artificial heart valves and the common approaches used in their modeling. This is followed by a detailed analysis of the dynamic mesh functionality and CFD solution is performed using the open-source library FOAM-extend. Part of the thesis focuses on evaluation of the geometry modifications from the perspective of forming the instabilities of the current and the course of force effects on the valve.
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.
Valves of the rocket fuel systems and engines
Kadlec, Jan ; Štefan, David (referee) ; Kozák, Jiří (advisor)
The main aim of this bachelor thesis is developing a search about rocket valves. For better understanding of the function and position valves is chosen a real rocket engine. The types of valves are described by shape of closing component. There are also mentioned the most common rocket fuels. The other aim is developed a simple design of shut-off valve with specialization on hydraulic losses.
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.
Hydraulic cylinder
Černý, Tomáš ; Kozák, Jiří (referee) ; Klas, Roman (advisor)
Bachelor thesis contains a brief description of the principle of operation of hydraulic motors, their use and computational relations. The main part of the research is devoted to hydraulic cylinders, their principle of function, division and construction. Also, a space for calculating the buckling stiffness of the piston rod is given. The next part deals with mathematical modeling of hydraulic mechanisms. A simple mathematical model is created in the case of a hydraulic cylinder with two identical piston rods and in the case of a differential piston. Based on the model, graphs of the frequency of oscillation are plotted. The possibilities of influencing the frequency of oscillating are explained by changing the parameters of the cylinder.
Possibilities to potentiate effect of non-opioid analgesics
Janovský, Martin ; Kršiak, Miloslav (advisor) ; Farghali, Hassan (referee) ; Kozák, Jiří (referee)
The aim of the present Thesis was to investigate the possibility of the improvement of analgesic efficacy of novel non-opioid analgesics selectively or preferentially inhibiting COX-2, coxibs and meloxicam, by combinations with other substancies. These analgesics have favourable profile of gastrointestinal tolerability. For this purpose, a few different approaches were used. Based on the published data, two members of the cyclooxygenase-2 inhibitors group were selected, etoricoxib and celecoxib, and their interactions with the weak opioid codeine were assayed. Analgesic efficacy of the individual drugs and their combinations was evaluated using the preclinical model of acute visceral pain (the writhing test), in mice, and the statistical method of isobolographic analysis was used to investigate the manner of interactions. Subsequently, the interactions of paracetamol and ibuprofen with codeine were also assayed using the same methods. The interaction between celecoxib and codeine was found to be additive, while that between etoricoxib and codeine was sub-additive. On the other hand, the interactions of paracetamol and ibuprofen with codeine were synergistic. In the second part of the Thesis, the potential improvement of the pharmacological properties of meloxicam was evaluated after its complexation with...

National Repository of Grey Literature : 27 records found   1 - 10nextend  jump to record:
See also: similar author names
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