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Ultrasonic anemometer
Hůlka, Jakub ; Mágr, Zdeněk (referee) ; Havlíková, Marie (advisor)
This master’s thesis deals with the construction and realization of an ultrasound anemo- meter. Individual types of anemometers are compared in this thesis, including mechanical, thermo anemometer and ultrasound anemometer. Different construction renderings and measurement principles of ultrasonic anemometers are analyzed. In addition, an experi- mental method of measuring the speed of sound by phase shift between two transmitting frequency is described in the document. This thesis includes the design of an control unit and the realization of a simple prototype of an ultrasonic anemometer. Experimental confirmation of the characteristics of the ultrasound anemometer is the last part of the document.
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Modelling of pressure pulsations in pipes
Hofírek, Michal ; Havlásek, Michal (referee) ; Himr, Daniel (advisor)
This diploma thesis deals with problem of water hammer in pipes affected by viscoelastic behavior of pipe material. Mathematical model uses pressure dependent speed of sound in water air mixture. For purpose of numerical solution the Method of Characteristics with independent time step is introduced. This method is compared with commonly used methods such as Method of Characteristics (MOC) and Lax Wendroff scheme. Derived model, solved with Method of Characteristics with independent time step, is verified with experimental simulation.
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Computational tool for fluid flow of gases through nozzles
Kozáková, Kamila ; Zálešák, Martin (referee) ; Klimeš, Lubomír (advisor)
This bachelor's thesis deals with thermodynamic relations of one-dimensional, adiabatic and steady flow through the duct. Thermodynamic terms, equations and principles, required for understanding the problems of fluid flow, are summed at the beginning. The greatest attention is paid to step-by-step solution of each case, which can occur. These analyses were implemented in a software for solving thermodynamic problems. Scripts and the graphical user interface were created in a programming language Python using its libraries. Last part of this work is focused on evaluating and testing problems of fluid flow through the ducts.
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Air valve as protection from water hammer
Sedlmajer, Jakub ; Machů, Tomáš (referee) ; Himr, Daniel (advisor)
The thesis deals with air valves, focusing on vacuum air valves. The theoretical part describes basic water hammer theory, especially low pressure problematics. Subsequently there are briefly explained any of usual water hammer protections, air valves function principles and differences in vacuum air valves constructions. The work is finished by measurement which evaluates reduction of pressure head according to use of this kind of protection.
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Možnosti snížení navlhavosti dřeva a přestupu vlhkosti do dřeva užitého v konstrukci rezonanční desky hudebního nástroje
Zatloukal, Petr
This theses is focused on possibilities of sorption properties decrease of musical instruments soundboards. This task should be solved with respect to sustainability of previous acoustics properties or their improving. The resonance wood specimens has been fabricated and conditioned to the relative humidity of 40 % The specimens were divided into three groups. The first one with natural properties, the second one treated by the temperature of 180 °C and the last one was treated by 200 °C. Specimens were conditioned all together to the relative humidity of 60 % and at the last step at 80 %. The conditioning was isothermal with the temperature of 20 °C. Swelling and hygroscopicity establishment was based on dimensions and weight measurement during conditioning of specimens. The first, second and longitudinal natural oscillation frequency of the specimens were determined by free-free resonant frequency method. Longitudinal and transversal sound propagation velocity were measured using Fakopp Ultrasonic Timer. Dynamic Young’s modulus (E´L,E´RT), dynamic bend Young’s modulus (Eb), acoustic constant (KL, KRT), characteristic impedance (ZL, ZRT), acoustic conversion efficiency (ACEL, ACERT), relative acoustic conversion efficiency (RACEL, RACERT) and damping coefficient (tan δ) were determined using the measured data. The treatment by 180 °C caused the decrease of volume swelling, which was 7,4% lower after the treatment. The hygroscopicity decreased by 2,8%. The treatment by 200 °C decreased swelling by 8,5% and the hygroscopicity by 4,3%. The different results of both treatments were observed in case of longitudinal sound velocity. In case of 180°C treatment the value of longitudinal sound velocity decreased by 1,6 %, whereas after treatment by 200 °C the increase by 2,1% was found. Acoustical properties E´, Eb, K, Z, ACE, RACE were decreasing due to the higher moisture content and tan δ was increased. Heat treatment by 180 °C has not significantly affected acoustical properties and sound velocity but the treatment by 200 °C caused their increase.
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Computational tool for fluid flow of gases through nozzles
Kozáková, Kamila ; Zálešák, Martin (referee) ; Klimeš, Lubomír (advisor)
This bachelor's thesis deals with thermodynamic relations of one-dimensional, adiabatic and steady flow through the duct. Thermodynamic terms, equations and principles, required for understanding the problems of fluid flow, are summed at the beginning. The greatest attention is paid to step-by-step solution of each case, which can occur. These analyses were implemented in a software for solving thermodynamic problems. Scripts and the graphical user interface were created in a programming language Python using its libraries. Last part of this work is focused on evaluating and testing problems of fluid flow through the ducts.
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Thermodynamics of 1D ideal gas flow in Matlab
Fúdor, Vlastimil ; Klimeš, Lubomír (referee) ; Štětina, Josef (advisor)
The aim of this bachelor's thesis is created toolbox which solve one-dimensional flow of ideal gas. This thesis is divided to three parts. In first part is explained physical foundations for understanding flow of ideal gas. Second part is focused on description functions of toolbox. This part can be considered like a help. In the third part are solved examples by created toolbox. Important part is zip file, which contains function of toolbox.
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