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Hodnocení závad vybrané funkční skupiny spalovacích motorů
Baka, Petr
The bachelor work deals with the rating of clink mechanism in combustion engine. The work is divided into three main parts. The first part pays attention to the recent situation of engine construction in today's passenger cars. The second one describes the construction and material composition of each parts of crank mechanism. The last part concentrates not only on the evaluation of the defects which arise on the crank mechanism, but also describes their dividing according to the cause of each defect
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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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Turbocharger Vibrations Generated by Internal Combustion Engine
Schulla, Radek ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
The content of this master’s thesis is the issue of turbocharger vibrations due to excitation from the internal combustion engine. The theoretical part deals with the noise and vibrations generated by turbochargers and internal combustion engines. It also discusses the effect of vibration on the turbocharger and its individual parts, including the effect of the internal combustion engine. Subsequently, a turbocharger model is created in ADAMS software, the rotor response in turbocharger operating speeds to various excitation frequencies is analyzed and finally the safety of fluid bearings is evaluated and modifications to reduce vibrations are proposed.
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The effect of texture geometry on friction and lubricating film formation in radial journal bearing
Katrincová, Tereza ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
The aim of this diploma thesis is to find out how the geometric parameters of circular textures affect the friction and lubrication in a conformal contact. The configuration of a partial, radial, hydrodynamic bearing was investigated on a modified block on-ring device, where the block was replaced by a sapphire section. The device allows simultaneous measurement of friction and optical observation of processes in contact. The light induced fluorescence method was used for the measurement of film thickness. None of the studied texture combinations had a positive effect on the transition from hydrodynamic mode to mixed lubrication mode. Textures in the narrow band of the combination of diameter and depth have a positive effect, outside of them negative effect of texture on friction and film thickness was observed.
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Bearings for machine spindles
Knápek, Jiří ; Nohál, Libor (referee) ; Galas, Radovan (advisor)
This bachelor’s thesis contains the survey of bearings for machine spindles. Thesis is especially focused on slide, air, magnetic and rolling bearings. Bearings are described with emphasis on their construction, lubrication and arrangements. In the end of this thesis there is a comparison of mentioned kinds of bearings for machine spindles.
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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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