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Non-isothermal flow in relative frame of reference
Koblížek, Martin ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
The aim of this graduation thesis is to investigate whether it is possible to design a fluid machine that would utilize a flow resulting from different densities of processing medium, to generate electricity. The thesis focuses on the determination of relations that have influence on the efficiency. The parametres influencing the degree of efficiency have been analyzed. The aim is to reach the highest possible degree of efficiency. Depending on the results, a suitable processing medium can be selected. Within the scope of the thesis, an experiment had been proposed that verified the ground principle of the non-isothermal flow occurence. In conclusion, the outcomes are evaluated with the view of a prospective further developement of the device.
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Identification of the contact angle anisotropy for hydrophobic surfaces
Simandl, Mirek ; Pochylý, František (referee) ; Fialová, Simona (advisor)
Bachelor thesis deals with the principle of solid/liquid interface. A water droplets behaviour is observed in contact with hydrophobic and superhydrophobic surfaces (contact angle exceeding 150°). The influence of the coating direction (unidirectional coating, perpendicular coating, both directions, uncoated and undefined) of the surface was evaluated. The contact angle anisotropy was examinedusing the SEE System software and its measuring accessories. Each sample was measured with three volumes of waterdroplet - 3l, 5 l and 10 l. Further, the influence of the structure on the droplet motion on an inclined plane was observed. Individual samples and groups with the same direction of the coating structure are evaluated. From these results are taken some general conclusions regarding to the influence of the direction of the structure and the droplet size on the contact angle anisotropy.
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The process of decompression in hydraulic systems of forming machines
Havelka, Milan ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
This thesis consists of two main parts. The first part is a theoretical analysis, or a literary research, it is focused on the physical properties of the fluid, which have direct impact on the decompression. The aim of the second part is to evaluate the measurement of the forging valve and subsequently simulate the issue by means of CFD. The first simulations were performed for the maximal valve stroke and used for the CFD solver setup calibration. The subsequent analyses dealt with possible openings of the valve. In the final chapter the theoretical impact of the liquid compressibility and of the undissolved air is discussed. The results of the thesis can prove useful for the new valve setting in hydraulic circuit or for possible geometry modification.
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Self-excited and forced pulsations of liquid in axisymmetric domain
Skopalová, Kristýna ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
The diploma thesis deals with the determination of the self-excited and forced pulsation of the real fluid in the cylindrical area and in the annulus. It also focuses on a case of resonance that has an unfavorable effect on the hydraulic circuit. The result of the thesis is the analytical relations for determination of self-excited and forced shapes of flow and pressure in the closed cylindrical area, for two selected variants of kinematic excitation. In the first variant, excitation is performed in the form of a sinus function. The second variant is expressed as a sawtooth function. A pulsation of the fluid caused by the movement of the body is described for the annulus. Further, in this area, the shapes of fluid pulsation are solved without external excitation.
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The centrifugal pump radial force reduction
Koutný, Luděk ; Haluza, Miloslav (referee) ; Pochylý, František (advisor)
This diploma thesis deals with problematics of the radial force effect on the runner and possibilities of the force reduction. Some pump modifications were proposed and changes of radial force magnitude in reverse blocking state and optimal flow state were examined in consequence. Following investigation was focused on the new modifications regarding to the pump efficiency and its characteristics stability. All results were carried out using the Solidworks, the Fluent and the Microsoft Excel software.
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Types and principles of water reservoirs
Cakl, Vojtěch ; Fialová, Simona (referee) ; Pochylý, František (advisor)
The bachelor thesis deals with decription of the water reservoirs, in particular for the purposes of the irrigation. In the first part of the thesis is overview of the functions and distribution by purpose and location to the consumption. Following is the proposal of the storage tank volume by purpose. In next part there is a description of the construction, shape and equipment of the water reservoir. Subsenquently there is expalained the principle on simple arithmetical example. The last part of the bachelor thesis focussing of multifunctional water reservoirs and their functions in relation to the landscape. It contains some examples and proper scheme of multifunctional water reservoir.
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Design study of sinusoidal pump
Grym, Ondřej ; Fialová, Simona (referee) ; Pochylý, František (advisor)
Bachelor`s thesis is oriented on literature search of sinusoidal pump and estimation from aspect cut down frictional force in sliding surface of cam chain guide. Constructive design will occupy oneself by reduction dissipation in run. Pumping medium will be water. Resulting design will print on 3D printer. One of parts is describe shop offer this product from different company.
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Rotating stall in a centrifugal compressor.
Guzej, Michal ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
This thesis deals with a procedure for determining the complete processing of aerodynamic flow instabilities (rotating stall and surge) in a centrifugal compressor. At small flows the performance of a compressor system is limited by the surge line, which is caused by flow instabilities. Numerical solution is obtained using the method of transfer matrix. This system is simulated through several models with local resistances that represent the dissipation of pressure energy. Pulses are excitated in these models by the pressure jump placed before the centrifugal compressor. From the frequency-amplitude characteristics for the selected range of frequencies and flow the impedance characteristic of the compressor system is determined. We are looking for problematic frequencies in this characteristic that cause flow instabilities in the compressor system.
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Self-priming pump
Kusý, Jan ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
This diploma thesis deals with analysis and description of principles of self-priming pumps and description of physical processes, that allow self-priming. With these basements should be proposed innovation of construction for selected type of pump.
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Mutual interaction of pressure pulsations and pulsations of undirect pipe
Hrazdíra, Zdeněk ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
This thesis deals with mathematical modeling of multiphysics FSI (fluid-structure interaction) problem, describing mutual interaction of pressure pulsations and vibrations of indirect pipe in a 2D region. Firstly, physical partial differential equations are derived separately for both media, which are in turn coupled and solved analytically. Results of mentioned models include natural frequency values, amplitude-frequency characteristics and both natural and driven damped oscillations of pipe and liquid.
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