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Modeling of airflow through the human vocal tract during voice production
Kučera, Marek ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This bachelor's thesis deals with computational modeling of air flow through the human vocal tract during voice production. In the theoretical part, the anatomy of the respiratory system, the function of the human vocal folds, the biomechanics of the human voice and the flow theory are briefly described. Subsequently, an overview of approaches to computational modeling of voice production is presented. The practical part describes the creation of 2D models of the trachea and vocal tract with different settings of the vocal folds. A suitable mesh of finite volumes was created. Stationary flow was solved and analyzed in the ANSYS Fluent program. A suitable time step was determined for non-stationary flow and the results were subsequently analyzed. At the end, the non-stationary flow with the prescribed movement of the vocal folds is solved.
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Computational modelling of blood flow in the carotid artery with serial stenosis
Lukáš, Petr ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
The aim of this bachelor's thesis is to analyse the effect of double stenosis on flow and stress characteristics in the carotid artery. First, based on the stated literature, a literature search is conducted regarding blood flow in the arterial system. Then, the procedure of creating idealized models of an artery with double stenosis and the procedure of mesh creation and numerical solution are described. The models have different size of the stenosis and different distance between stenosis. In the final stage, the results are analysed first for stationary flow, then one model is selected on which is performed the analysis for pulsating flow. Analytical calculation of pressure drop and comparison with numerical calculation is also part of this work.
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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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Simulation of temperature and airflow in a field distributor with frequency converter
Melechovský, Ondřej ; Maxa, Jiří (referee) ; Ondříček, Adam (advisor)
Presented work deals with heat transfer and its methods. At the beginning thesis describes the theory and the ways of heat transfer with connected quantities and equations. Then it explains the stack effect and impact of temperature on electro technical device. In work is also described ABB driver ACS line and calculation of heat transfer according to IEC 60890 standard. In the practical part there is the calculation of heat transfer in Flow Simulation simulating CFD program solved and finite element method is mentioned. Important part of work is devoted to setting and optimization of simulation. In conclusion are made some changes of construction of driver, dependence on heat transfer is inspected.
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Pulse flow of liquid in flexible tube
Komoráš, Miroslav ; Šedivý, Dominik (referee) ; Klas, Roman (advisor)
This master’s thesis is dealing with analysis of fluid flow pulse in a flexible tube representing e.g. an artery in a human body. In ANSYS program, 3D simulations were performed, and these are so-called interrelated FSI analysis. In Maple software, 1D simulations of fluid flow in the tube were performed for various thin-walled and thick-walled variants. The aim is using these programs to determine the flow rates and pressures in the tube, its wall deformation and stress. Therefore, the theoretical part deals mainly with basic equations of flow dynamics, linear and nonlinear models and rotationally symmetric vessels. In the computational part are described individual procedures in the mentioned programs.
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Analysis of the gas flow in the passage of the primary electron beam differentially pumped chamber depending on the shape of the nozzle inlet
Hladký, David ; Vaculík, Sebastian (referee) ; Maxa, Jiří (advisor)
It is necessary to separate sample chamber with pressure up to 2000 Pa and the surroundings of tube with pressure 0.01 Pa with help of a differential pumped chamber at the environmental scanning electron microscope This differential pumped chamber is to be designed so that it has to manage to separate sections with very different pressures sufficiently and in the trajectory of transitting (overflying) prime electrons the average value of pressure and density has to be as low as possible, so that it would occure the lowest diffusion of these electrons, which is caused by collisions of electrons and air molecules too. It were created axisymmetric 2D models variant of Differentially pumped chamber with different opening angles of the clone, which were analyzed to choose the best variant. The Ansys Fluent systeme using finite volume method for analysis of fluid flow was used for analysis.
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Analysis of the gas flow when pumping vacuum for newly designed scintillation detector
Poruban, Milan ; Vaculík, Sebastian (referee) ; Maxa, Jiří (advisor)
The aim of this thesis is to study the issue of eniveromental scanning electron microscopy and pumping gas to create vacuum in the newly designed scintillation detector. Further, creating a model of recently proposed scintillation detector and simulating and analyzing pumping gas in differentially pumped chamber of detector. The theoretical part deals with electron microscopy, electron sources, electron optics and secondary electrons detectors. It is also presented which signals are generated by the electron beam on the surface of a solid. Further fluid flow issues and equations describing the flow in the solved chamber are dismantled. Furthermore, the impact of gaseous environment on the trajectory of primary electrons, because there are collisions of primary beam with atoms and molecules of gas. The following section discusses creating, quality and importance of the network in mathematical modelling. A method of a final volume used to calculate the differential equations describing the flow of gas at the premises of the detector is described . The practical part consists in creating a model of scintillation detector and analyzing the gas flow in drawing a vacuum in the newly designed scintillation detector. At the end the simulation results of gas flow are compared for different variants of apertures and various pressures on the neck of a scintillation detector designed for optimum performance of the detector. The outcome of this thesis is model of newly designed scintillation detector with optimized shapes of apertures according to functional requirements.
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Air flow load on a roof structure induced by a helicopter during erection works
Fidler, Tomáš ; Križan, Jiří (referee) ; Nevařil, Aleš (advisor)
Diploma thesis is focused on modeling rotor downwash generated by the main rotor of helicopter and analyzing its effects on the roof structure. Theoretical definition of rotor downwash flow is described in the first part of the text. Governing equations of computational fluid dynamics are briefly explained as well as boundary layer and finite volume method. Next part inquires into numerical simulation of rotor downwash based on height of rotor above the roof, shape of roof plane and climatic conditions. Results are compared with climatic load values provided by actual Czech construction standard in the end of the text.
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Calculation of transformer cooling
Hetflajš, Martin ; Cipín, Radoslav (referee) ; Janda, Marcel (advisor)
This master´s thesis deals with influence of forced air flow from the ventilators on the power transformer cooling. For this analysis was used simulation software ANSYS CFX, that uses the finite volume method for calculations of dynamic properties of liquids. In the introduction of the thesis is presented the basic terminology of fluid flow, temperature fields and theory of transformers. The simulation is divided to the analysis of flow through the left and right radiator models.
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