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Methods for Determination of Characteristic Parameters of Combustion Processes on the Basis of Experiments and Modeling
Bělohradský, Petr ; Klemeš,, Jiří (referee) ; Žitný, Rudolf (referee) ; Stehlík, Petr (advisor)
The present thesis is concerned with methods for determination and modeling of characteristic parameters of combustion of gaseous fuels. The focus is stressed on formation of nitrogen oxides and heat transfer from hot flue gases into combustion chamber’s walls. Experimental work, which is focused on testing of two burners with suppressed formation of nitrogen oxides, is an important part of the thesis. Its aim is to obtain data that is necessary for further processing and modeling. The work presents two methods that may be used in modeling of characteristic combustion parameters, namely the method based on statistical processing of data and the method based on computational fluid dynamics. The approaches are applied to two devices (burner with two-staged fuel supply, burner with two-staged air supply) with the objective to analyze their parameters. First approach covers detailed planning of burner test prior to its own carrying out (definition of the goal of experiment, choice of input factors and response, experimental plan) and subsequent statistical processing of experimental data. On the contrary, CFD approach offers simulations as an alternative option to traditional experimental methods. The simulation of combustion includes building of computational grid, setup of boundary conditions, turbulence model, heat transfer model and chemical kinetics. Results of simulations are compared with experimental measured data.
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Global optimization of multiple variables functions
Vláčil, Stanislav ; Janda, Marcel (referee) ; Kloc, Petr (advisor)
Master’s thesis deals with numerical finding the global minimum. A theoretical part of project presents a problem of global optimization, her basic division and shows basic examples the specific problems of global optimization. Further, the reader is familiar with the basics of some numerical methods and with description of their strengths and weaknesses. A practical part shows concrete algorithm of global optimization, its use on data of specified function. Data refer to the issue of radiative heat transfer.
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Dynamic and heat transfer analysis of a container with measuring instruments for space probes
Zolotarev, Igor ; Bula, Vítězslav ; Šnábl, Pavel ; Gabriel, Dušan ; Dobiáš, Jiří ; Masák, Jan ; Snížek, Jan ; Souček, Jan
Rocket boosters and spacecraft are subject to intense acoustic environments during launch, which induce high levels of vibration in structural elements and equipment. In addition, elastic structural interactions with propulsion systems and flight control systems can produce low-frequency, high-deflection flight instabilities. Natural vibration of the container with measuring equipment were studied by numerical and experimental methods in the laboratory of Institute termomechanics CAS. Heat transfer analysis inside the container was made by FEM with respect to the conditions during start of the rocket and work in space.\n
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Methods for Determination of Characteristic Parameters of Combustion Processes on the Basis of Experiments and Modeling
Bělohradský, Petr ; Klemeš,, Jiří (referee) ; Žitný, Rudolf (referee) ; Stehlík, Petr (advisor)
The present thesis is concerned with methods for determination and modeling of characteristic parameters of combustion of gaseous fuels. The focus is stressed on formation of nitrogen oxides and heat transfer from hot flue gases into combustion chamber’s walls. Experimental work, which is focused on testing of two burners with suppressed formation of nitrogen oxides, is an important part of the thesis. Its aim is to obtain data that is necessary for further processing and modeling. The work presents two methods that may be used in modeling of characteristic combustion parameters, namely the method based on statistical processing of data and the method based on computational fluid dynamics. The approaches are applied to two devices (burner with two-staged fuel supply, burner with two-staged air supply) with the objective to analyze their parameters. First approach covers detailed planning of burner test prior to its own carrying out (definition of the goal of experiment, choice of input factors and response, experimental plan) and subsequent statistical processing of experimental data. On the contrary, CFD approach offers simulations as an alternative option to traditional experimental methods. The simulation of combustion includes building of computational grid, setup of boundary conditions, turbulence model, heat transfer model and chemical kinetics. Results of simulations are compared with experimental measured data.
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Global optimization of multiple variables functions
Vláčil, Stanislav ; Janda, Marcel (referee) ; Kloc, Petr (advisor)
Master’s thesis deals with numerical finding the global minimum. A theoretical part of project presents a problem of global optimization, her basic division and shows basic examples the specific problems of global optimization. Further, the reader is familiar with the basics of some numerical methods and with description of their strengths and weaknesses. A practical part shows concrete algorithm of global optimization, its use on data of specified function. Data refer to the issue of radiative heat transfer.
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Factors Influencing Thermal Radiative Properties of Metals
Králík, Tomáš ; Hanzelka, Pavel ; Musilová, Věra ; Srnka, Aleš
Data on thermal absorptivity and emissivity are important for calculations of heat flows in cryogenic devices. Although thermal radiative properties of materials used in cryogenics are measured, published and used for more than sixty years we have noticed that sometimes users of that data don’t well understand the significance of individual factors influencing thermal radiative properties. The sensitivity of the thermal radiative properties of metals to the condition of the surface and the difficulty of measurement, especially at low temperatures is probably the reason of dispersion of the published values. The effect of the material and its purity, finishing (machining, mechanical or chemical polishing) and of the protective coatings or accidental layers (water, oxidation) on the thermal radiative properties is not always obvious. Influence of the material, surface treatment, roughness and layers on the surface is discussed on the basis of our 20 year experience with measurement of the emissivity and absorptivity in the range from 20 K to 300 K.
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