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Gas exchange systems of two-stroke engines
Kovář, Michal ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
This bachelor thesis is focused on the analysis of the development and critical evaluation of the gas exchange system of two-stroke engines. The aim of the work was to use research to concentrate various options for gas exchange system of two-stroke engines of various power categories, to describe individual solutions and point out the advantages and disadvantages of individual systems and then outline possible future developments in this area.
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Adapter for pressing of sport shockabsorber
Drozd, David ; Jeniš, Filip (referee) ; Mazůrek, Ivan (advisor)
This bachelor thesis is aimed at developing an adapter intended for filling mono-tube shock absorbers with gas. The first part deals with fundamentals and methods of gas charging of shock absorbers. The second part is aimed at designing the adapter based on findings from the first part. The third part includes detailed description of the final design and control calculations. Thesis outcomes include complete technical documentation of filling adapter of custom design and a comprehensive research report concerning gas charging of shock absorbers.
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Gas exchange systems of two-stroke engines
Kovář, Michal ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
This bachelor thesis is focused on the analysis of the development and critical evaluation of the gas exchange system of two-stroke engines. The aim of the work was to use research to concentrate various options for gas exchange system of two-stroke engines of various power categories, to describe individual solutions and point out the advantages and disadvantages of individual systems and then outline possible future developments in this area.
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Adapter for pressing of sport shockabsorber
Drozd, David ; Jeniš, Filip (referee) ; Mazůrek, Ivan (advisor)
This bachelor thesis is aimed at developing an adapter intended for filling mono-tube shock absorbers with gas. The first part deals with fundamentals and methods of gas charging of shock absorbers. The second part is aimed at designing the adapter based on findings from the first part. The third part includes detailed description of the final design and control calculations. Thesis outcomes include complete technical documentation of filling adapter of custom design and a comprehensive research report concerning gas charging of shock absorbers.
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Investigation of droplet nucleation in CCS relevant systems – design and testing of the expansion chamber
Čenský, Miroslav ; Hrubý, Jan ; Vinš, Václav ; Hykl, Jiří ; Šmíd, Bohuslav
A unique in-house designed experimental apparatus for investigation of nucleation of droplets in CCS relevant systems is being developed by the present team. The apparatus allows simulating various processes relevant to CCS technologies. Gaseous mixtures with CO2 are prepared in a Mixture Preparation\nDevice (MPD) based on accurate adjustment of flow rates of individual components [EPJ Web of Conferences 143, 02140 (2017)]. The mixture then flows into an expansion chamber, where it undergoes a rapid adiabatic expansion. As a consequence of adiabatic cooling, the mixture becomes supersaturated and nucleation and simultaneous growth of droplets occurs. In this study, we describe the design and testing of the expansion part of the experimental setup. The rapid expansion was realized using two valve systems, one for low pressures (up to 0.7 MPa) and the other for high pressures (up to 10 MPa). A challenge for a proper design of the expansion system is avoiding acoustic oscillations. These can occur either in the mode of Helmholtz resonator, where the compressible gas in the chamber acts as a spring and the rapidly moving\ngas in the valve system as a mass, or in the “flute” mode, where acoustic waves are generated in a long outlet tubing.\n
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Experimental research of heterogeneous nuclei in expansion chamber
Bartoš, O. ; Hrubý, Jan ; Kolovratník, M.
An expansion chamber has been developed to investigate experimentally homogeneous and heterogeneous nucleation processes in steam. A chamber design allows to measure in the laboratory but also in power plants using the steam withdrawn from the steam turbine. The purpose of the device is to provide a new approach to study the physics of non-equilibrium wet steam formation, which is one of the factors limiting the efficiency and reliability of steam turbines. The expanded steam or a known mixture of steam with a non-condensable gas rapidly expands in the expansion chamber. Due to adiabatic cooling, the temperature drops below the actual dew point. When reaching a sufficiently high supersaturation, droplets are nucleated. By tuning the supersaturation in the so-called nucleation pulse, particles of various size ranges can be activated. This fact is used in the present study to measure the aerosol particles present in the air. Homogeneous nucleation was negligible in this case. The experiment demonstrates the functionality of the device, data acquisition system and data evaluation methods.
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Experimentální studie o matematickém modelování velmi rychlého pneumatického systému
Hrubý, Jan ; Šmíd, Bohuslav ; Pavelka, Miroslav ; Krejčí, A. Petr
We provide some general considerations for design, mathematical modeling, and experimental testing of pneumatic systems with typical transient times of 1 ms. The gas flow is typically critical or near-critical, with significant compressibility effects. We provide a lumped model of a pneumatic system, incorporating the balances of mass, energy and momentum. We show that inertia of the gas plays an important role. For a particular system, designed for application in fundamental research of aerosol particles, we show a reasonable agreement of the lumped model with experimental test of the prototype.
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