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Calculation of aerodynamic characteristics of a vehicle under yaw conditions
Mračnová, Michaela ; Popela, Robert (oponent) ; Vančura, Jan (vedoucí práce)
This diploma thesis focuses on unsteady CFD simulations of a vehicle with different geometric modifications exposed to side wind. The first part of the thesis deals with the evaluation of the aerodynamic characteristics of the vehicle under static yaw conditions determined by the unsteady calculation methodology and the subsequent validation of the used methodology based on the comparison of the results with experimental data. With use of given methodology, the second part of this thesis focuses on representation of unsteady effects occurring under exposure to atmospheric crosswind.
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Multiphase flow simulation of mixing phenomena in a chemical reactor
Novosád Kluknavská, Júlia ; Kožušník, Martin (oponent) ; Klas, Roman (vedoucí práce)
The Present Master Thesis deals with industrial mixing and CFD simulation thereof. The Thesis in qualitative terms covers a theoretical background of mixing processes, i.e. gives general overview of industrial mixers and their purposes, introduces the individual types of impellers and provides the basic recommendations for mixing apparatus geometry assembly. The main part of the Present Thesis is aimed at practical application of CFD simulation in industry. To create a physically correct CFD model it is necessary to validate it by an experiment. Hence, there was designed and performed one. The experiment captured water level shape influenced by vortex flow as well as recorded a dissolution time of solid crystalline matter. The same was simulated by CFD. Final comparison of CFD simulation and experiment resulted in agreement of water level shape and depth. The model for simulating a dissolution phenomenon correlates to the real physical process, but needs to be improved. The Thesis, however, contains description of a suitable way how to proceed to obtain a CFD model which covers dissolution of crystalline substances correctly in physical terms.
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Membránové čerpadlo
Veselý, Přemysl ; Dobšáková, Lenka (oponent) ; Pochylý, František (vedoucí práce)
Ústředním cílem této práce je analyzovat výkon membránového čerpadla tak, aby byl schopen provozu za daných podmínek, který v této chvíli nesplňuje. V první části práce byla vytvořena základní rešerše o membránových čerpadlech a o jejich jednoduchém rozdělení, zařazení do objemových čerpadel a historie jejich vývoje. V následující kapitole byla popsána podrobně jejich konstrukce a význam každého dílu stroje. Dále zde bylo provedeno několik základních CFD výpočtů s cílem lokalizovat místa největších hydraulických ztrát. Tyto analytické výpočty byly následně porovnány s praktickými experimenty, z čehož byl vyvozen závěr. V dalším bodě bylo na základě těchto skutečností provedeno několik konstrukčních úprav s cílem pokusit se zlepšit výkon celé soustavy. Poté byla tato konstrukční opatření ještě prozkoumána a vyhodnocena
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Influence of Membrane on Airflow in Historical Attic Spaces: The First Principles Study Using CFD Models
Poljak, Michal ; Ponechal, Radoslav ; Krušinský, Peter
This paper conducts an initial analysis of the impact of a vapour permeable membrane on airflow within triangular attic spaces, resembling the shape and dimensions of medieval sanctuaries found in historical rural churches in our region. The first principles study, using Computational Fluid Dynamics (CFD) based on the simulation models, aims to identify potential challenges and research directions regarding how the application of this membrane may affect the microclimatic conditions in the attic spaces and the durability of the historical timber trusses. One significant outcome of the study reveals that on a simulated extremely hot summer day, the application of the vapour permeable membrane reduced airflow by 10 to 15 per cent, thus affecting the overall microclimate in the attic.
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Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna ; Bílek, Vojtěch ; Haidl, Jan ; Isoz, M. ; Pivokonský, Martin
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
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Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna ; Bílek, V. ; Haidl, J. ; Isoz, Martin ; Pivokonský, M.
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
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Modelování mazací soustavy turbodmychadla
Breckl, Lukáš ; Hliník, Juraj (oponent) ; Novotný, Pavel (vedoucí práce)
Diplomová práce obsahuje rešeršní část zaměřenou na konstrukci turbodmychadla, mazací soustavu motoru a turbodmychadla, základní fyzikální vlastnosti mazacích olejů a hydrodynamiku. Cílem práce je vytvořit analytický a CFD výpočetní model mazací soustavy turbodmychadla. Na jejich základě stanovit výstupní tlaky a měrné ztrátové energie místních odporů.
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Design of modular tubular heat exchanger
Marx, Sven ; Turek, Vojtěch (oponent) ; Jegla, Zdeněk (vedoucí práce)
The main goal of this thesis is to get acquainted with the process requirements and the design of a cross flow heat exchanger, as well as evaluating the design with the help of simulation software. First the operation conditions for waste heat recovery and general design options are examined and the basic thermal and hydraulic equations are presented. The main part of this thesis concentrates on a modular cross flow tubular heat exchanger proposed for experimental research of the heat recovery and fouling process of the flue gas produced from the combustion of alternative at Brno University of Technology (BUT) at the Institute of Process Engineering (UPI). First the given situation in the testing laboratory is briefly explained. Then the simulation of the proposed heat exchanger design with the software HTRI is described and the results are summarized and compared with the target requirements for the design. The tube-side water flow distribution inside of one of four identical heat exchanger modules is analyzed with the help of CDF software using three different simulation approaches. Two approaches using the k--SST turbulence model and one using the k--Realizable turbulence model are described from generating the CAD model over meshing and setting the boundary condition to running the simulation. In the end the differences between the approaches and results of the flow distribution simulations are discussed.
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Simulace koncových elementů
Bombera, Jiří ; Rubinová, Olga (oponent) ; Uher, Pavel (vedoucí práce)
Diplomová práce obsahuje simulace koncových elementů metodou CFD. Cílem práce je stanovit typ koncového elementu, který nejlépe provětrá místnost rodinného domu s přihlédnutím na rychlost proudění vzduchu v pobytové zóně a stáří vzduchu v místnosti. Závěrem práce je návrh systému vzduchotechniky pro rodinný dům s aplikací koncových elementů vyhodnocených jako ideální pro provětrání místností.
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