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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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Vliv zadní části karoserie na aerodynamickou interakci vozidel
Vondruš, Jan ; Blaťák, Ondřej (oponent) ; Vančura, Jan (vedoucí práce)
Diplomová práce je zaměřena na CFD simulaci jízdy skupiny dvou za sebou jedoucích vozidel DrivAer v různých karosářských variantách. Pro karosářské varianty Estateback, Fastback a Notchback jsou vytvořeny CFD modely, které jsou následně řešeny pomocí turbulentního modelu k-epsilon. Cílem práce je analýza vlivu zadní části karoserie vozů na jejich aerodynamické charakteristiky s ohledem na jízdu ve skupině.
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Vstupní recirkulace u odstředivého čerpadla
Heinz, Pavel ; Štefan, David (oponent) ; Rudolf, Pavel (vedoucí práce)
Tato diplomová práce se zabývá fenoménem objevujícím se v hydrodynamických čerpadlech při pod-optimálním průtoku. Tímto fenoménem je vstupní recirkulace, jež je nežádoucím jevem v sání čerpadla. Tato recirkulace způsobuje kavitaci, tlakové pulzace a může způsobit ucpání sacího potrubí. Hlavním cílem diplomové práce je výpočtové modelování proudění pro režim s recirkulací, identifikaci proudových jevů a návrh možných opatření, která by vstupní recirkulaci potlačila.
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