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Design of device for water jet erosion of materials
Mikulášek, Tomáš ; Kárník, Jan (referee) ; Rudolf, Pavel (advisor)
The aim of this diploma thesis was to design experimental setup for planar samples erosion by means of the water jet on the rotational sample configuration, laboratory experimental testing and its evaluation by means of the 3D optodigital microscope Olympus DSX 510. There were observed typical erosion patterns at the solid tested material surfaces as well as the cavitation erosion. Experiments were carried out at the following water pressures: 0.432 MPa, 1.50 MPa on the rotating sample, at 2.50 MPa on steady sample and on flooded sample for different treatment times. Experimental results of waterjet impact on rotating sample were compared with the theoretical modelling data obtained by CFD modelling. Computational modelling was done in two parts: 3D modelling of water jet flow impact on rigid steady surface and 3D modelling of water jet impact on rigid moving surface. The latter modelling was solved as two phase modelling, where the computational model “Volume of Fluid” was employed. The aim of the study was to find out for the individual cases under study appearance of the water flow and the changes of the magnitude of the force of the impinging water jet on the wall.
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Cavitation erosion
Lecnar, Lukáš ; Hudec, Martin (referee) ; Rudolf, Pavel (advisor)
This bachelor’s thesis focuses on cavitation erosion and it is divided into two main parts. The first part is devoted to the search of cavitation erosion focusing on erosion mechanisms. In the first chapter of this search is briefly described cavitation process and different types of cavitation are listed here. Hydrodynamic cavitation which is the key type for this bachelor’s thesis is described in the following chapter. The final and the most extensive chapter is devoted to cavitation erosion of solids which is largely associated with the effects of the mechanical action of the fluid. The second part is devoted to the experimental study of cavitation erosion of samples. The goal was to document the experiment which was carried out in order to gain knowledge about the material removal by cavitation erosion.
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Experimental testing of hydrocyclone
Juráš, Filip ; Hudec, Martin (referee) ; Rudolf, Pavel (advisor)
This bachelor thesis is focused on experimental testing of hydrocyclone. The work is divided into two parts. The first part describes basic parts of hydrocyclone, dimensions, and operating parameters of the tested hydrocyclone and principles of its work. The second, practical part, describes the general preparation of the experiment, which started with searching for a suitable material and continued to the filter device used for particle separation.
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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.
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Hydraulic design of inducer fuel pump for rocket engine
Kadlec, Jan ; Rudolf, Pavel (referee) ; Štefan, David (advisor)
The aim of this masters thesis is hydraulic design of inducer for given pump geometry and operating parameters. The first part of this thesis deals with cavitation problematic in hydrodynamic pumps. Next section describes two-dimensional design of the inducer and according to that, the 3D CAD model of inducer is made. The later part deals with thorough CFD analysis and determination of the main hydraulic parameters of inducer itself and also with whole pump completed with this inducer. The last section is devoted to inducer design improvement.
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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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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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Lagrangian tracking of the cavitation bubble
Bossio Castro, Alvaro Manuel ; Zatočilová, Jitka (referee) ; Rudolf, Pavel (advisor)
In this thesis, the dynamics of an isolated cavitation bubble submerged in a steady flow is studied numerically. A Lagrangian-Eulerian approach is considered, in which properties of the fluid are computed first by means of Eulerian methods (in this study the commercial CFD software Ansys Fluent 19 was used) and the trajectory of the bubble is then computed in a Lagrangian fashion, i.e. the bubble is considered as a small particle moving relative to the fluid, due to the effect of several forces depending on fluid's pressure field, fluid's velocity field and bubble's radius. Bubble's radius dynamics, modeled by Rayleigh-Plesset equation, has a big influence on its kinetics, so a special attention is given to it. Two study cases are considered. The first one, motivated by acoustic cavitation is concerned with the response of the bubble's radius in a static flow under the influence of an oscillatory pressure field, the second one studies the trajectory of the bubble submerged in a fluid passing by a Venturi tube and a sharp-edged orifice plate.
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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.
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