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Flow structure and energy transformation in an elbow draft tube
Štefan, David ; Skoták, Aleš (referee) ; Rudolf, Pavel (advisor)
Draft tube is very important part of hydraulic turbines. Only optimum work together with turbine can bring highest performance of this machine set. Hence it is necessary to deal with character of flow in the draft tube for different operating conditions. Efficiency of the draft tube depends on many phenomena of flow. Observing these phenomena and finding their relation with energetic transformation in the draft tube is a suitable tool to judge quality of draft tube performance. Incorrect design of the draft tube can sometimes cause lower efficiency of whole machine set. The goal of this thesis is finding the main reasons causing draft tube efficiency drop for given operating conditions.
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Vortical structures with cavitating core
Švaňhal, Radek ; Štigler, Jaroslav (referee) ; Rudolf, Pavel (advisor)
The master's thesis focuses on vortical structures with cavitating core, which might develop in Francis turbines at non-optimal discharges in a form of unstable vortex cord. The cavitating vortex core is to be generated in a lab by flow rotation and a convergent nozzle. The objective of this thesis is to compare experimental results with mathematical model of pressure drop in vortical flow and with numerical calculation in Fluent based on finite volumes method. Other objective is to messure high frequency pressure vibrations generated by cavitating vortex core and spectrally analyze the data.
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Modeling two-phase bubble flow in microfluidics
Stehlík, Martin ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
The goal of submitted thesis is to perform a computer simulation of bubble creation in T-channel. In the first section of the paper, the theoretical applications of microfluidic bubble, micromachines and droplet formation are described. In the second part of the text, author uses cross flowing method for simulation od bubble creation. Furthermore, several settings in computer simulation software Fluent are mentioned. In addition, the influence of velocity at the T-channel inlet on surface tension and on bubble length is presented.
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Hydrodynamic cavitation in minifluidic Venturi nozzle
Zeman, Radek ; Hudec, Martin (referee) ; Rudolf, Pavel (advisor)
This thesis deals with cavitation on a small scale. Conducting experiments on a small scale helps to save time, space, and most importantly money needed for research. Low-energy operation on small scales could accelerate the development of larger-scale devices for practical use in industry. Hydrodynamic cavitation has proven to be a potentially useful tool for some industrial applications, such as water purification. In the practical part of this thesis, a cavitation visualization device operating with flow rates in milliliters per second is proposed. Devices similar to this one could be used in the near future to obtain the benefits previously mentioned, and thus promote research in the field of water purification using hydrodynamic cavitation.
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Fractal geometry application for orifice plate design
Hochman, Ondřej ; Fic, Miloslav (referee) ; Rudolf, Pavel (advisor)
Bachelor thesis consists of three parts. The first part is focused on research study of cav-itation and fractal geometry. It is concerned with the physical principle of cavitation, its generation, dynamics and implosion of cavitation bubbles. It also turns attention to useful application. Brief explanation of fractal geometry follows, including some famous examples. Two fractal shaped orifices were designed in the second experimental part, having the same cross-section as orifice with ordinary circle hole. These orifices were compared to each other from perspective of hydraulic losses.
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Installations in the draft tube of the swirl turbine
Kilian, Ondřej ; Rudolf, Pavel (referee) ; Haluza, Miloslav (advisor)
Diploma thesis deals with design and exploration of installation in the draft tube of the swirl turbine. Use of the draft tube is defined in the first part, with illustration of energetical gain and efficiency of draft tube. Further the suitable shape of draft tube is studied by CFD computing. Design, research and evaluation of installation in the draft tube are solved in the main part.
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Mutual interaction of magnetic field and cavitating flow
Harazin, Přemysl ; Štigler, Jaroslav (referee) ; Rudolf, Pavel (advisor)
Presented work consists of research and experimental part. Main focus of the research part is on mutual interaction between magnetic field and water and between magnetic field and cavitating flow. Prediction of the result is almost impossible, because the opinions on the effects differ, sometimes even go against each other. Experimental part consisted of three trials with permanent magnets. Electromagnetic probe was employed for measuring of the voltage. It appears, that magnetic field affects the cavitation, because in all of the trials the measured voltage changed after the switch from non-cavitating to cavitating flow. The change of the voltage was not great enough, thus application of this phenomenon in practice cannot be recommended.
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Disc friction of centrifugal pumps
Homola, Tomáš ; Klas, Roman (referee) ; Rudolf, Pavel (advisor)
This diploma thesis discusses the issue of the fluid flow instabilities due to rotating discs. It also deals with the calculation of axial force in centrifugal pumps and pressure distribution on cover and support disc of the impeller. Computational simulation of rotating disc is presented with the aim of capturing flow instabilities. Next computational simulation focuses on modelling a gap between the support disc (rotor) and the stator part of the pump for three different geometries, where axial force, pressure distribution on the support disc and loss torque are calculated for each of three models. Obtained results are then compared with the experiment in the conclusion
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Application of bionics for hydraulic turbine blade design
Kaprinay, Zoltán ; Moravec, Prokop (referee) ; Rudolf, Pavel (advisor)
This bachelor’s thesis deals with application of bionics for girl turbine blade design. In the first part the basic theoretical concepts of bionics are explained, and there are different inventions described which are inspired by nature from both past and present. The description of the principle and fiction of girl turbine is followed by designing the blade. Calculations are based on real data for the girl turbine. In the end of the work there is the 3D model of designed blade.
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Microfluidics
Abrahám, Martin ; Sluše, Jan (referee) ; Rudolf, Pavel (advisor)
The bachelor's thesis deals with phenomenon of gas and fluid flow in equipment with micro scale. The first part is dedicated to describe Reynolds number and laminar flow in micro channel. The second part is dedicated to describe specific equipment for pumping a working material – micropumps, microvalves, microneedels, micromixers.
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