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Design of nozzle for ozone admission
Krajcar, Ivo ; Hudec, Martin (referee) ; Rudolf, Pavel (advisor)
The thesis consists of three main parts. The first part contains a research focused on cavitation and fractal geometry. Furthermore it researches disinfection, mainly disinfection using UV radiation and ozone. It is concluded by mentioning advanced oxidising processes used for dangerous pollutant elimination and pointing out of positives and negatives of the individual technologies. The main goal of the fractal geometry research was to briefly explain what a fractal is and how to create different types and degrees of fractals. The second part of the thesis contains a simplified description of the design of a fractal orifice with air suction. This orifice is compared to a simple orifice with a circular opening in the last part of the thesis. Both orifices have the same cross section flow area. This part also describes a simple UV reactor design process. The third part of the thesis describes the experimental measurements of both of the orifices. The data gained from the measurements show that the fractal orifice has a better mixing influence than the circular one and also that the fractal orifice has a wider operational range than the circular one.
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Cavitation behind porous orifice
Livora, Tomáš ; Zeman, Radek (referee) ; Rudolf, Pavel (advisor)
This bachelor's thesis deals with the research and experimental verification of cavitation in a porous medium. The research part addresses the inception of cavitation on an orifice plate with one or more holes and the inception of cavitation on a porous structure. In this section, several geometric parameters are established, based on which porous materials can be compared. Their influence on the inception of cavitation is also outlined. In the experimental part, several orifice plates with a porous structure are designed and manufactured based on these parameters, and their properties are subsequently measured in a hydraulic circuit. The evaluated data determine the impact of individual parameters on the inception and course of cavitation.
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Utilization of hydrodynamic cavitation for water treatment
Balko, Marek ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
This bachelor thesis deals with the observation of features of cavitation with emphasis on the hydrodynamical cavitation and its use for eliminating unwanted and badly degradable compounds from water. Thanks to high temperature and pressures that are present at a colapse of cavitation bubbles the water decomposes into highly reactive hydroxile radicals which are able to decompose even. This effect can furthermore be strenghtened by the use of advanced oxidation processes – AOP. The experimental part of thesis is dedicated to examining a ability of hydrodynamical cavitation degrade particular chemical substance from water, namely estrogen.
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Monitoring of hydraulic machines using acoustic emissions
Závorka, Dalibor ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
The goal of this diploma thesis is to clarify possibilities of usage of acoustic emission as a hydraulic machinery diagnostics tool. Especially for exposing presence of ruptures or cracks in the parts of machine, assuming changes in acoustic exposure of the part during operation. This clarification is based on series of simple measured experiments, which consist of monitoring the bolt placed in fluid stream inside of a pipe. This bolt was preloaded against inner wall of pipe by appropriate tightening torque. This preload is supposed to simulate effects of the size of rupture. High preload simulates small rupture or none in object and respectively small preload is supposed to simulate big rupture. A group of pressure sensors and accelerometers measures experiments and their evaluations are processed by script created in software MATLAB. Outputs of this script are charts with effective values of respective sensors from the entire record split into individual frequency spectrums. These charts compare spectrums of each configuration to judge effects of parameters changes.
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Influence of fractal geometry on turbulent flow
Hochman, Ondřej ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
The master’s thesis deals with computational fluid dynamics (CFD) of two orifices, that have different shapes of holes but similar cross-sectional flow areas. The first of them is orifice with circular-shaped hole, which is used for maintenance free measurement of flow. The second one is orifice with fractal-shaped hole, inspired by von Koch snow-flake. This thesis follows bachelor thesis, in which was experimentally examined, that fractal-shaped orifices have better hydraulic properties (hydraulic losses and lower pressure pulsations) than circle-shaped one. The main target is to confirm this conclusion based on experiment, this time using CFD with various types of turbulence modelling ap-proaches. Both single phase (cavitation free) and multiphase numerical simulations were realized. Each model was compared from perspective of hydraulic and dynamic charac-teristics.
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Cavitating jet
Kotoulová, Helena ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
Předložená diplomová práce se zabývá kavitujícím paprskem a je rozdělena do tří hlavních částí. Teoretická část popisuje základní principy kavitace a její negativní účinky na povrch obtékaných těles (např. hydraulických strojů). Rozsáhlá kapitola je také věnována popisu samotného kavitujícího paprsku včetně mechanismů jeho vzniku, růstu a kolapsu. Další podkapitola je zaměřena na modely kavitační eroze, které mají velký význam pro predikci kavitační eroze ve fázi výpočtové simulace. V experimentální části je popsáno testování vzorku mědi inspirované normou ASTM G134 a následné vytvoření grafů kumulativního hmotnostního úbytku a rychlosti úbytku hmotnosti. Dále byla také provedena vizualizace pomocí vysokorychlostní kamery, aby bylo možné podrobně prozkoumat dynamické chování kavitujícího paprsku. Poslední část je zaměřena na numerické simulace pomocí výpočtového modelování proudění, tzv. Computational Fluid Dynamics (CFD), a na predikci kavitační eroze. Z důvodu optimalizace úlohy bylo provedeno více výpočtů na různých typech sítí s různými modely turbulence. Následně byly výsledky ze simulací vyhodnoceny a společně s výsledky z experimentu byly použity pro predikci kavitační eroze.
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Analysis of measured signals from cavitation experiments
Asszonyi, Ondřej ; Habán, Vladimír (referee) ; Rudolf, Pavel (advisor)
This thesis focuses on problem with detection of cavitation in hydraulic systems and devices. Thesis works with data from cavitation tunnel experiment, where cavitation appeared on blade. It founds out if time records and their frequency spectrum is dependent on operating conditions. Data are examined by various statistic methods. All of that is then used in method called neural network.
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Hydraulic characteristics of the cavitation nozzles
Gríger, Milan ; Habán, Vladimír (referee) ; Rudolf, Pavel (advisor)
The main goal of this thesis is the examination of hydraulic characteristics for different cavity nozzles, influence of liquid rotation and visualization of cavitating flow. Thesis is divided into two parts, theoretical and practical. Theoretical part deals with the description of cavity - creation, development and its extinction. This part also contains description of vortex flow and basic vertex models. Practical part compares nozzles performance experimentally. The aim of experiment was to measure hydraulic characteristics and their comparison. Jet performance was judged using visualizations and measured data was processed in Microsoft Excel and Parametr.
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