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Aerodynamic components of passenger cars
Petrskovský, Adam ; Vančura, Jan (referee) ; Vondruš, Jan (advisor)
This bachelor thesis is focused on aerodynamics of the cars. Theories on aerodynamics characterizations as well as force exertions are presented here. Moreover, the influence of aerodynamics on fuel consumption and formation of harmful emissions is described. The thesis also provides a comprehensive overview of particular aerodynamic devices used on cars. Furthermore, CFD simulations of four aerodynamic devices on a simplified model of car are included. The results of these simulations are then evaluated and the respective aerodynamic devices are subsequently compared to find out which of them has contributed the most to the improvement of aerodynamic characteristics of the vehicle.
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Quantitative comparison of used mesh for CFD software ANSYS Fluent
Koudelková, Kateřina ; Klas, Roman (referee) ; Štefan, David (advisor)
Creating a good computational mesh is one of the crucial activities in any CFD calculation. CFD software aim to make a mesh generation as simple and automated as possible, due to its time-demanding nature. ANSYS Fluent has introduced a tool for partially automatic mesh generation, a method called Mosaic mesh, which should ensure that the best type of mesh element is used in each part of the geometry for optimal results. Polyhexcore is the latest computational mesh generation method used by Mosaic mesh technology. This thesis aims to compare the Polyhexcore mesh with other types of computational meshes on an aerodynamic test problem.
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Validation of Selected Software in Terms of Air Age Simulation
Kučírek, Pavel ; Šikula, Ondřej
The paper pertains to the assessment of indoor air quality in terms of its air age in a ventilated space. It involves a comparison of Computational Fluid Dynamics (hereinafter CFD) simulation software and their validation by an experiment carried out in a test chamber. A total of 14 cases were simulated and compared using the software: OpenFOAM, Blue CFD-AIR, DesignBuilder, and Ansys. The aim is to evaluate the accuracy and usability of the software by comparing selected computational domains and meshes. The results obtained show that the assessed software achieves satisfactory accuracy for air velocities and air ages. Models with simplified inlet geometry and half-domain offer the best balance between accuracy and computational effort.
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Numerical and Experimental Investigation of the Flow Field in Five Blade Linear Cascade in Subsonic Flow
Šnábl, Pavel ; Chindada, Sony ; Bublík, O. ; Procházka, Pavel P. ; Prasad, Chandra Shekhar
In large steam turbines, last stage blades are very long and must be designed very thin and with no shroud to minimize the centrifugal force which leads to low eigenfrequencies and low structural damping. In this case, aero-elastic damping plays important role on last stage bladed disc’s dynamics. Three major aero-elastic issues found in turbomachinery are forced response, non-synchronous vibrations, and flutter. Flutter is an unstable, self-excited vibration resulting from coupling between the structural vibrations and unsteady aerodynamic forces. It is clear that this unstable behaviour must be avoided and predictions of flutter behaviour need to be performed during design stage of the turbine.\n
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Analysis of Whirling of Gas Flow within the Specimen Chamber of ESEM
Bayer, Robert
The usage of an Environmental scanning electron microscope (ESEM) brings the possibility of studying many kinds of materials and chemical reactions never studied before. In this article there are compared and analyzed several simulation results of gas flow in the specimen chamber of ESEM with high gas pressure throughout the whole volume except on its optical axis, where low gas pressure is needed.
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Mathematical-physical analysis of dynamic pressure for the experimental differentially pumped chamber
Lepltová, Kristýna ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
This thesis is based on the series of scholarly article dedicated to the issue of pumping in the differential scanning chamber of an environmental scanning microscope. The thesis is based on Danilatos’s study where the pumping of the differential pumped chamber is solved by means of the Monte Carlo statistical method. The thesis analyzes gas flow in the experimental chamber using the Pipot tube. The analyses will be used for the design of the experimental chamber which will serve for the experimental evaluation of the flow results in the chamber using the continuum mechanics.
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The effect of the shape of the intake ports for pumping in a Scintillation detector.
Flídr, Karel ; Vyroubal, Petr (referee) ; Maxa, Jiří (advisor)
The thesis is concerned with the design of the shape of suction canals used for pumping in the scintillation detector. The goal is to perform analysis of the model of the detector according to the current conception and then perform an optimalisation of the suction canals as per demands to their function. In the beginning of the thesis the history of the microscope and electron microscopy is described. The next chapter is focused on a more detailed description of ESEM. The following charter is dedicated to describing the scintillation detector.The thesis recounts the kinds of liquid flow. In conclusion the programs SolidWorks and Ansys Fleunt are described. Next part of this thesis describes in detail parameters‘ settings of simulation calculation. Following chapter introduces designed changes of suction channels shape and its results are shown and described.
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Computational analysis of fluid flow in a tumble dryer
Dohnal, Miloslav ; Juřena, Tomáš (referee) ; Hájek, Jiří (advisor)
The aim of this work is to create a computational model of radial industrial tumble dryers, to calculate and identify the amount of air that flows through the inside of the drum itself. The calculation will be performed via computational fluid dynamics (CFD). Furthermore, compile transient balance model of mentioned dryers. Perform simulation balance model and compare the results of simulations with experimental measurements. By comparing the experimental data and simulation to determine the degrees of freedom of balance model and evaluate their impact on the assembled transient model. For a better understanding of the drying process, there is constructed a system of differential equations describing heat and moisture within the material being dried on a simple model. In the section devoted to the computational analysis of fluid flow is analyzed existing geometry of the drum, which has a major impact on the flow of air inside the drum itself. Following describes how to simplify its complex geometry entering the computational fluid dynamics. Then, there is carried out a simulation of fluid flow inside the tumble dryers using MRF and Sliding Mesh models. Finally, there is an analysis of the data obtained and determined the average amount of air flowing through the drum itself. On the contrary, the aim of the work is not to create another text tool for students engaged in CFD theme.
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Modelling of flow and pressure characteristics in the model of the human upper respiratory tract under varying conditions
Karlíková, Adéla ; Forjan,, Mathias (referee) ; Paštěka, Richard (advisor)
Cílem této diplomové práce je vytvořit 3D model horních dýchacích cest podle originálního modelu segmentovaného z CT dat, aplikovat různé podmínky na průtok vzduchu v modelu, a poté hodnotit změnu charakteristik rychlosti a tlaku. Model horních dýchacích cest byl vytvořen v prostředí softwaru ANSYS, který využívá výpočetní dynamiku tekutin, a byly použity Navier-Stokesovy rovnice pro modelování průtoku vzduchu v modelu. Nejprve byl vytvořen jednoduchý 2D model za účelem seznámení se s prostředím ANSYS. Dále byl zkonstruován 3D model horních dýchacích cest a byly modelovány charakteristiky rychlosti a tlaku za různých podmínek. Tyto podmínky zahrnují různé umístění a množství míst pro odběr vzorků v modelu a výběr různých kombinací vstupů. Nakonec byly prezentovány a hodnoceny výsledky spolu s ilustracemi modelů modelovaných za různých podmínek. 3D model lze považovat ze kompromis mezi výpočetní náročností a složitostí modelu a lze jej použít jako základ pro další výzkum.
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