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Properties and application of ferrofluids
Vaverka, Jakub ; Šedivý, Dominik (referee) ; Zbavitel, Jan (advisor)
Ferrofluids are substances that can change their properties through an external magnetic field. The theoretical part of this bachelor thesis explains the nature and properties of these liquids, and how they are made. The next chapter provides concrete examples of ferrofluid use, and where it is possible to direct current research. The principal objective of the experimental part is to measure and evaluate the surface tension of two different samples of kerosene-based ferrofluids.
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CFD simulation of the hydrokinetic energy converter using flow-induced vibrations
Vaverka, Jakub ; Bezdíček, Jiří (referee) ; Klas, Roman (advisor)
Flow-induced vibrations on bodies of different shapes are investigated by CFD simulations. The influence of the mass of the body, the spring stiffness and the value of the added damping on the dynamic behaviour of the system is evaluated. A combination of the 6DOF function and a dynamic computational mesh is used to move the body around the y-axis solely by fluid flow. The output is an evaluation of the forces acting on the body, the trajectory of the body and the possible power that the body could generate by its motion.
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Investigation of properties of Faraday cup with split collector
Havelka, Matěj ; Pavlů, Jiří (advisor) ; Vaverka, Jakub (referee)
Solar wind is plasma propagating from the Sun through interplanetary space. For determination of the parameters of this cosmic plasma, spacecraft often carry so-called Faraday cups, which can be used to determine the energy distribution function of ions in the plasma. Apart from energy distribution, it is necessary to study other parameters, such as composition and direction of travel of the particles. Direction measurements in the solar wind can be performed using a Faraday cup with a split collector plate into two or more sections. This technique is employed, for example, in the BMSW-LG instrument, which is designed for in situ measurements in the vicinity of the Moon's surface. The gap in between sections of the collector plate can introduce unwanted effects into the measurement, therefore new setup has been developed for the purpose of testing the BMSW-LG instrument and to study effects of the gap on plasma diagnostics. In this setup, an ion beam is used to scan the surface of the collector plate while measuring ion currents from all electrodes. The BMSW-LG instrument was tested thoroughly and then gradually heated up to 70 ◦ C to determine the stability of electrometric amplifiers. Effects of the gap were studied at different energies and angles. From the measurements, it can be concluded that the...
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Properties and application of ferrofluids
Vaverka, Jakub ; Šedivý, Dominik (referee) ; Zbavitel, Jan (advisor)
Ferrofluids are substances that can change their properties through an external magnetic field. The theoretical part of this bachelor thesis explains the nature and properties of these liquids, and how they are made. The next chapter provides concrete examples of ferrofluid use, and where it is possible to direct current research. The principal objective of the experimental part is to measure and evaluate the surface tension of two different samples of kerosene-based ferrofluids.
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Proposal of detector for measurements of plasma environment near the Moon
Ďurovcová, Tereza ; Šafránková, Jana (advisor) ; Vaverka, Jakub (referee)
When the Moon is outside the Earth's magnetotail, its surface is directly ex- posed to the particles coming from the Sun. It is a consequence of a fact that the lunar surface is not protected by a global magnetic field or atmosphere. However, small-scale crustal magnetic fields have been found near the lunar surface; some of them can form so-called minimagnetospheres. Consequently, the vicinity of the Moon represents an interesting environment for the study of many processes in the solar wind plasma. The thesis is devoted to the proposal of a configuration of detectors for measurements of parameters in this plasma environment. The new device BMSW-LG which consists of the proposed configuration of detec- tors should monitor at 50−100 km altitude above the lunar surface on an orbit perpendicular to the ecliptic, and simultaneously compare the results with solar wind measurements. Experiences with the BMSW device were applied to this proposal. The SIMION software package which allows to test the trajectories of charged particles in electric fields inside the detector was used for simulations of the detector configuration.
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