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Possibilities of using magnetically active liquids in microfluidics
Glozigová, Anna ; Štigler, Jaroslav (referee) ; Fialová, Simona (advisor)
Diplomová práce se zabývá magneticky aktivními kapalinami a jejich aplikacemi v mikrofluidice. V první části práce je provedena rozsáhlá rešerše tématických celků, které se problematiky dotýkají. Tato část zahrnuje podrobný přehled základů magnetismu, magneticky aktivních kapalin a mikrofluidiky s přihlédnutím k tzv. milifluidice a mikromagnetofluidice. V této části jsou i, mimo jiné, představeny aplikace a problematika nestabilit spojených s mazáním hydrodynamických kluzných ložisek. Druhá oblast je zaměřena na praktickou část, je zde popsán návrh a realizace experimentu, stejně jako výpočtové simulace provedené pomocí softwarů FEMM a ANSYS Fluent. Třetí část obsahuje rozpravu koncept potenciálního využití magneticky aktivní kapaliny v milikanálcích za účelem regulace nežádoucích jevů spojenými s nestabilitami mazacího oleje v hydrodynamických ložiscích.
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Design of Turbocharger Bearing for Low Viscosity Oils
Plánka, Jakub ; Dlugoš, Jozef (referee) ; Novotný, Pavel (advisor)
The first part of the thesis describes journal bearings characteristics, their function and lubrication. The second part of the thesis is about a rotor-dynamics issue and how to use numerical and experimental methods for verification of a new bearing design. The practical part of the thesis is focused on analyse a current design of bearings in MBS. In the last part has been made and verified a new bearing design.
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Experimental study of fluid-induced instabilities in journal bearings
Stifter, Jan ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
Presented diploma thesis deals with experimental study of fluid induced instabilities which occur in rotating machinery with journal bearings. The first part describes the oil whirl and oil whip instabilities. It also gives an example of optical methods used for observation of journal bearings. Next part is dedicated to modifications of an existing test rig that were necessary for carrying out experiments. Finally, there are presented results of experiments that define the effect of initial conditions on appearance of instabilities.
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Friction reduction by surface texturing
Mauer, Milan ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
The aim of this diploma thesis is to experimentally elucidate the connection between the friction of the specimen with the textured surface and the optical observation of the sliding contact surface. The thesis focuses on the configuration of the journal bearing. This configuration is achieved by replacing the block with a circular sapphire section on a block-on-ring tribometer. For exploring of the lubricant film formation, the method of optical interferometry and fluorescence is implemented on the block-on-ring tribometer. These adjustments allow examination of the effect of the textured surface on the friction coefficient and the thickness of the lubricant film. In a mixed mode, the textures cause a significant increase in friction values and reduce the thickness of the lubricant film. The negative influence of dimples increases with the increasing radial load size. In the hydrodynamic mode, the textures have a lower negative effect on the resulting values than in the mixed mode. The changes are dependent on the size of the radial load and the viscosity of the lubricant. In the hydrodynamic mode, cavitation was not observed, and the effect of the textured surface does not correspond to theoretical prerequisites, which is reflected by lower lubricant thickness and higher friction.
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Experimental study of fluid-induced instabilities in journal bearings
Stifter, Jan ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
Presented diploma thesis deals with experimental study of fluid induced instabilities which occur in rotating machinery with journal bearings. The first part describes the oil whirl and oil whip instabilities. It also gives an example of optical methods used for observation of journal bearings. Next part is dedicated to modifications of an existing test rig that were necessary for carrying out experiments. Finally, there are presented results of experiments that define the effect of initial conditions on appearance of instabilities.
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Friction reduction by surface texturing
Mauer, Milan ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
The aim of this diploma thesis is to experimentally elucidate the connection between the friction of the specimen with the textured surface and the optical observation of the sliding contact surface. The thesis focuses on the configuration of the journal bearing. This configuration is achieved by replacing the block with a circular sapphire section on a block-on-ring tribometer. For exploring of the lubricant film formation, the method of optical interferometry and fluorescence is implemented on the block-on-ring tribometer. These adjustments allow examination of the effect of the textured surface on the friction coefficient and the thickness of the lubricant film. In a mixed mode, the textures cause a significant increase in friction values and reduce the thickness of the lubricant film. The negative influence of dimples increases with the increasing radial load size. In the hydrodynamic mode, the textures have a lower negative effect on the resulting values than in the mixed mode. The changes are dependent on the size of the radial load and the viscosity of the lubricant. In the hydrodynamic mode, cavitation was not observed, and the effect of the textured surface does not correspond to theoretical prerequisites, which is reflected by lower lubricant thickness and higher friction.
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Design of Turbocharger Bearing for Low Viscosity Oils
Plánka, Jakub ; Dlugoš, Jozef (referee) ; Novotný, Pavel (advisor)
The first part of the thesis describes journal bearings characteristics, their function and lubrication. The second part of the thesis is about a rotor-dynamics issue and how to use numerical and experimental methods for verification of a new bearing design. The practical part of the thesis is focused on analyse a current design of bearings in MBS. In the last part has been made and verified a new bearing design.
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Design of an experimental rig for testing of internal-combustion engine journal bearings
Bedeč, Csaba ; Repka, Martin (referee) ; Omasta, Milan (advisor)
This thesis deals with the structural design of a test rig for combustion engine bearings with static and dynamic loading capabilities. The first part of thesis summarizes materials, geometries and possible bearing failures, then analyzes existing test rigs. The second part contains different solutions and summarizes these solutions to a final design. The last part contains analysis of possible failure of the test rig and solutions for these problems. The thesis contains drawings prepared for manufacturing and a design report.
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