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Radial turbine runner design with reduced moment of inertia
Votava, Ondřej ; Skalka, Petr (referee) ; Fuis, Vladimír (advisor)
This master’s thesis deals with topological optimization of the impeller of a radial turbocharger turbine. It focuses on reducing the moment of inertia with unchanged aerodynamic properties. The optimization was carried out using CFD, thermal and structural analysis. The computational modeling was performed using the finite element analysis in ANSYS. The work proposes models of the impeller with the topological modification of the internal structure. Based on the values of moment of inertia, the stress and the strain the most suitable model was selected.
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Torsion of bars with noncircular cross section
Votava, Ondřej ; Hájek, Petr (referee) ; Profant, Tomáš (advisor)
The aim of this bachelor's thesis is the problematics of twisting of bars with non-circular cross-section. In order to solve this problem, analytical and numerical methods are used. The theoretical part deals with the derivation of elementary relations, especially on the thin-walled open and closed section. This theoretical knowledge is further applied to solve specific tasks. In this thesis, the applicability of using individual methods for real parts is examined.
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Radial turbine runner design with reduced moment of inertia
Votava, Ondřej ; Skalka, Petr (referee) ; Fuis, Vladimír (advisor)
This master’s thesis deals with topological optimization of the impeller of a radial turbocharger turbine. It focuses on reducing the moment of inertia with unchanged aerodynamic properties. The optimization was carried out using CFD, thermal and structural analysis. The computational modeling was performed using the finite element analysis in ANSYS. The work proposes models of the impeller with the topological modification of the internal structure. Based on the values of moment of inertia, the stress and the strain the most suitable model was selected.
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Reactions of Hydrogen Molecules with Ions and Recombination of H+3 Ions with Electrons at Cryogenic Temperatures
Hejduk, Michal ; Glosík, Juraj (advisor) ; Čížek, Martin (referee) ; Votava, Ondřej (referee)
We studied how distribution of nuclear-spin states of H+ 3 ions or H2 molecules influence rate coefficients of H+ 3 -electron recombination or reactions of H2 with N+ or H+ , with regard to kinetic and internal temperatures of the reactants. Experiments were carried out in plasma environment or in an ensemble of ions in an ion trap. Main diagnostic methods were the Langmuir probe diagnos- tics, laser absorption- and mass spectroscopy. The distribution of nuclear spin states (para and ortho) was varied using a specially constructed para-hydrogen generator. We performed pioneer measurements of the rate coefficients for the nuclear-spin-state-selective binary and ternary H+ 3 -electron recombination in thermalised plasma. We performed studies of N+ + para/ortho-H2 reaction with high accuracy and interpreted the results as dependent on fine structure states of N+ ions. We measured a temperature dependence of the rate coeffi- cients for radiative and ternary channels of H+ + para/ortho-H2 association. 1
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Creation and characterization of cold molecules and molecular radicals in supersonic plasmatic nozzle
Mašát, Milan ; Votava, Ondřej (advisor) ; Glosík, Juraj (referee) ; Španěl, Patrik (referee) ; Kania, Patrik (referee)
Title: Creation and characterization of cold molecules and molecular radicals in supersonic plasmatic nozzle Author: Milan Mašát Department: J. Heyrovsky Institute of Physical Chemistry of the ASCR, v. v. i. (32-UFCHAV) Supervisor: Mgr. Ondřej Votava, Ph. D., J. Heyrovsky Institute of Physical Chemistry of the ASCR, v. v. i. (32-UFCHAV) Abstract: The aim of this work is the development and characterization of experimental apparatus designed for study of expansion-cooled stable and unstable molecule species in near infrared region, as well as associated methodology. This device consists of discharge source of cold molecular radicals and a system for their spectroscopic analysis. The source and the spectroscopic part changes and upgrades are described in detail. Characterization of radical source and its methodology was done on the OH radical model. Changes in radical properties under different experimental conditions, such as stagnation pressure, used voltage and different geometries of both the nozzle and electrodes are measured. Methodology of spectroscopic analysis was carried out on methane molecule in unassigned part of spectra, so called icosad region. Keywords: supersonic expansion, molecular radical source, high resolution spectroscopy
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Torsion of bars with noncircular cross section
Votava, Ondřej ; Hájek, Petr (referee) ; Profant, Tomáš (advisor)
The aim of this bachelor's thesis is the problematics of twisting of bars with non-circular cross-section. In order to solve this problem, analytical and numerical methods are used. The theoretical part deals with the derivation of elementary relations, especially on the thin-walled open and closed section. This theoretical knowledge is further applied to solve specific tasks. In this thesis, the applicability of using individual methods for real parts is examined.
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Study of H3+ recombination in selected quantum states
Varju, Jozef ; Glosík, Juraj (advisor) ; Votava, Ondřej (referee) ; Novotný, Oldřich (referee)
Title: Study of H3 + recombination in selected quantum states Author: Jozef Varju Department : Department of Surface and Plasma Science Supervisor of the doctoral thesis: Prof. RNDr. Juraj Glosík, DrSc., Department of Surface and Plasma Science Abstract: In this work measurement of the effective recombination rate coefficient of H3 + dominated and recombination governed afterglow plasma at 77 K and 145 K are presented. Population of para-H3 + in the studied plasma has been varied by using para enriched H2 as a precursor along with normal H2. Time resolved NIR-CRDS was used to in-situ measure the number density evolution of the two lowest rotational states of H3 + . Measurements at different para to ortho H3 + ratios, at otherwise identical conditions, allowed for extrapolation of the effective recombination rate coefficient of pure para-H3 + and ortho-H3 + . From measured dependences on the buffer gas densities the values of the recombination rate coefficients for the binary and ternary channel are determined of para-H3 + and ortho-H3 + . Keywords: recombination, spectroscopy, H3 + , para H2
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Získávání empirických energií základních stavů pomocí teplotní analýzy spekter z dusíkem chlazené kyvety a superosonické trysky
Mašát, M. ; Votava, Ondřej
In this paper we presented a method for determination the lower state energies, and hence the rotational quantum number, in the overtone spectra of methane (the Icosad polyad, between 7076 to 7291 cm-1). The method explores the temperature dependence of rovibrational transition intensities. In the first part of this report this approach is used with spectra measured at a) 81 K in liquid nitrogen cooled cell [Kassi et al., 2008] and b) 25 K in supersonic jet expansion. In the second part we demonstrate how the temperature-dependent line intensities can be directly extracted from the pulsed supersonic expansion experiment.
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Charakterizace supersonického radikálového zdroje
Mašát, M. ; Votava, Ondřej
Experimental setup for spectroscopic measurements of molecular radicals at low temperatures is presented. Radicals are created in a DC discharge and cooled by supersonic expansion. Absorption spectroscopy in the near IR region is used to probe the neutral transient species formed in the discharge, using tuneable extended cavity diode lasers. Initial characteristics of the radical source are presented; discharge current-voltage characterization, molecular OH radical concentrations and temperature were measured.
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