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Extrapolation of diagrams of resistance coefficients using virtual experiment
Koreň, Denis ; Vondál, Jiří (referee) ; Juřena, Tomáš (advisor)
As a part of pneumatic breaking systems, disc valves are used for very small actuations of the valves, for which no values for pressure losses are found in literature. The correct design shall be made conditional on the total pressure loss of system, a part of which also occurs in the flow of the given valve. The work is initially devoted to a description of the calculation of the resistance coefficient and the characteristics of the physical processes during the flow in the idealized valve. Consequently, design of the model for the flow at the entrance into the valve end at the exit from the valve, including the setting of the simulations in the Fluent, is clarified. An important part of the work are sensitivity tests of the model to Reynolds number, to the model of turbulence and the mesh resolution near the wall. In addition, the results of simulations for various relative scales of the model are compared with experimental data given in the literature. The outputs of the work are the resistance coefficients, which extrapolate the data in the available resources, especially for valves with small relative actuation (h/Dh
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Simplified flow distribution modelling
Rebej, Miroslav ; Vondál, Jiří (referee) ; Turek, Vojtěch (advisor)
Tato diplomová práce se zaměřuje na modelování proudění tekutiny v paralelních distribučních systémech, kde hraje důležitou roli rovnoměrnost distribuce tekutin. Pro tento účel je vytvořen vlastní CFD kód. Kód je napsán v programovacím jazyce Java a používá ke zlepšení výkonu knihovny třetích stran, které se vyznačují přímým přístupem ke hardwarovým a systémovým prostředkům. Kód se také vyznačuje určitými zjednodušeními, u nichž se očekává, že sníží výpočetní časy. Vliv použitých zjednodušujících opatření je vyhodnocen porovnáním výsledků simulací proudění na několika geometriích s údaji získanými z podrobných modelů CFD. Geometrie použitých svazků trubek se odlišují různými uspořádáními toku a trubek a také různým počtem trubek.
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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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Simplified computational modelling of biomass grate combustion
Floková, Kateřina ; Vondál, Jiří (referee) ; Hájek, Jiří (advisor)
The aim of this thesis is to assemble simplified computational 3D model for straw grate combustion, based on data provided by detailed computational 1D model. This thesis is organized as follows. Firstly, current state of CFD grate combustion modelling is described. The main body of this thesis is focused on creation simplified 3D model, which includes pressure losses calculation, aproximation of data provided by outcomes of detailed 1D model and analysis of heat transfer during combustion process. Simulation results dealing with radiation heat transfer and heat conductivity are included in conclusion.
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Computational Modeling of Turbulent Swirling Diffusion Flames
Vondál, Jiří ; Klemeš,, Jiří (referee) ; Tuček,, Antonín (referee) ; Hájek, Jiří (advisor)
Schopnost predikovat tepelné toky do stěn v oblasti spalování, konstrukce pecí a procesního průmyslu je velmi důležitá pro návrh těchto zařízení. Je to často klíčový požadavek pro pevnostní výpočty. Cílem této práce je proto získat kvalitní naměřená data na experimentálním zařízení a využít je pro validaci standardně využívaných modelů počítačového modelování turbulentního vířivého difúzního spalování zemního plynu. Experimentální měření bylo provedeno na vodou chlazené spalovací komoře průmyslových parametrů. Byly provedeny měření se pro dva výkony hořáku – 745 kW a 1120 kW. Z měření byla vyhodnocena data a odvozeno nastavení okrajových podmínek pro počítačovou simulaci. Některé okrajové podmínky bylo nutné získat prostřednictvím dalšího měření, nebo separátní počítačové simulace tak jako například pro emisivitu, a nebo teplotu stěny. Práce zahrnuje několik vlastnoručně vytvořených počítačových programů pro zpracování dat. Velmi dobrých výsledků bylo dosaženo při predikci tepelných toků pro nižší výkon hořáku, kde odchylky od naměřených hodnot nepřesáhly 0.2 % pro celkové odvedené teplo a 16 % pro lokální tepelný tok stěnou komory. Vyšší tepelný výkon však přinesl snížení přesnosti těchto predikcí z důvodů chybně určené turbulence. Proto se v závěru práce zaměřuje na predikce vířivého proudění za vířičem a identifikuje několik problematických míst v použitých modelech využívaných i v komerčních aplikacích.
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CO2 reduction with algae
Naider, Jakub ; Rebej, Miroslav (referee) ; Vondál, Jiří (advisor)
The aim of this final thesis is the process of algae cultivation their use for carbon dioxid reduction. The main objective of this work is the mass and heat balance of the photobioreactor and the design of a temperature control system. Within the research work, an overview of certain types of bioreactors and photobioreactors, the current situation around the climate and the impact of the cultivation of algae on carbon dioxide emissions. The model for temperature control and mass transfer of a plate photobioreactor is created in this work.
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Small heating units - emissions - fuels - choice
Coufal, Martin ; Vondál, Jiří (referee) ; Kermes, Vít (advisor)
The first part of thesis focuses on an overview of small heat energy sources. Second part is an overview of available fuels and their related emissions. The third part is the creation of the basic algorithm to select the heat source. The last part is application of the proposed model to the virtual house Cesmína.
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CFD modelling of granular flow in rotary kiln
Slowik, Roman ; Vondál, Jiří (referee) ; Juřena, Tomáš (advisor)
This work deals with modeling the flow of particulate matter in rotary kilns. For this purpose, a combined CFD and Discrete Element Method (DEM) model was used. Using Ansys Fluent software, several simulations were performed in order to determine the mean residence time and movement of the material in the rotary drum dryer. Results of the computational model were used to develop a regression model of the mean residence time and compared to the values as given by empirical equations. Furthermore, a simplified sensitivity analysis was performed for the selected input parameters of the model such as the stiffness constant, air mass flow rate and the particle size.
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Local heating units for family house - case study
Nováček, Milan ; Touš, Michal (referee) ; Vondál, Jiří (advisor)
This thesis deals with selected methods of heating a house. The first part is dedicated to familiarization with the possibility of local heating of houses and the analysis of individual sources and heating equipment. The second part describes the designed family house. For this house were proposed some proposals by heating. The next step was to evaluate the individual proposals and select three that were assessed in terms of economic analysis. Economic analysis compared the start-up costs and operating costs. The proposals were compared with existing heating systems. At the end of the proposals was evaluated and determined the best method of heating the house.
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Development of computational tool for engineering
Komiš, Jan ; Hájek, Jiří (referee) ; Vondál, Jiří (advisor)
The thesis aims to provide insight into the use of Python in engineering calculations. The thesis has been divided into a theoretical and practical part. The theoretical part introduces Python and its possible uses in the field of engineering. The second section of the theoretical part describes key choices of study resources and provides instructions on how to set up Python from the perspective of a common user. The final part of the thesis deals with the choice of appropriate libraries (SciPy, NumPy, Cantera, etc.) and shows how these can be used practically in specific tasks from the fields of thermomechanics and hydromechanics.
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