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Optimization of vortex pump
Šmíd, Pavel ; Bílek, Martin (referee) ; Pochylý, František (advisor)
The aim of this labor is to optimize the vortex pump. When this pump should find application on the field of health like human heart for extracorporeal circulation. We will deal with the analysis of shear stress in the pump and its size of it and consider the use nonwetting surfaces to reduce the shear stress values. All our analysis will be made by CFD calculations.
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Sludge Pumping on WWTP
Fadrný, Tomáš ; Medek, Jaroslav (referee) ; Boráň, Jaroslav (advisor)
This diploma thesis deals with the best solution design for a sludge fitting, especially focusing on the right choice of pumps for the waste water treatment plant in Prostějov. The pumps were selected for a circulation pipeline, which heats up the sludge. Several measurements were carried out in order to determine the statistical evaluation of the properties of the pumped medium. The figures gained were used to calculate pressure losses.The diploma thesis is divided into two parts. The first part provides a theoretical analysis of the problem and the second part presents the results and subsequently the reasoning for the new selection of pumps in order to change the WWTP technology from the mesophilic to the thermophilic sludge digestion. The test records describing the testing of the individual samples of the pumped sludge are attached.
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Modeling of Liquid Film Instabilities with Subsequent Entrainment of Droplets
Knotek, Stanislav ; Kozubková, Milada (referee) ; Čermák, Libor (referee) ; Jícha, Miroslav (advisor)
This dissertation deals with instabilities of thin liquid films up to entrainment of drops. Four types of instabilities have been classified depending on the type of structure and process on the liquid film surface: two-dimensional slow waves, two-dimensional fast waves, three-dimensional waves, solitary waves and entrainment of drops from the film surface. This thesis analyzes the physical principles of instabilities and deals with the mathematical formulation of the problem. Shear and pressure forces acting on the surface of the liquid film are identified as the cause of instabilities. Mathematical models for predicting instabilities are demonstrated using approaches based on solving the Orr-Sommerfeld equation and the equations of motion in integral form. Models of shear and pressure forces acting on the surface of the film and selected models of film thickness are presented. The work is focused on the prediction of the initiation of two-dimensional waves using the integral approach. Shear stress and pressure forces acting on the liquid film surface have been modeled using the simulation of air flow over a solid surface. Finally, criteria for drop entrainment are presented with their dependence on air velocity and film thickness.
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Influence of interference fit on Rolling Bearing life
Tetour, Stanislav ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
Master thesis is focused on the influence of interference fit on rolling bearing life. The first part of thesis deals with the theoretical knowledge, that is necessary for the solution. The influence of interference fit was investigated of inner ring on shaft and outer ring in housing bore for recommended tolerance classes. Interference fit was solved on cylindrical roller bearing and tapered roller bearing. Analytical and numerical approach was used for the solution. A static analysis of bearing was made using program ANSYS Workbench in numerical section. The output of analysis was maximum shear stress under the contact surface, which result is contact fatigue of bearing. Bearing life was determined by life factor, which indicates bearing life with interference fit compared to bearing without interference fit.
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Dynamic viscosity of asphalt binders
Broďák, Marek ; Coufalík, Pavel (referee) ; Dašek, Ondřej (advisor)
The bachelor thesis describes a laboratory characteristics of bituminous binders. The principle, procedure of meansurment and comparison of test results of dynamic viscosity, needle penetration and softening point by ring and ball method will be described. The tests will be performed on samples of the bituminous binders with different degree of modification.
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Shear stress relaxation of bituminous binders in DSR
Musil, Vladimír ; Hegr, Zdeněk (referee) ; Dašek, Ondřej (advisor)
The thesis describes the relaxation properties of bituminous binders determined in dynamic shear rheometer (DSR). Paving bitumen, polymer modified bitumen (PMB) and crumb rubber modified bitumen (CRmB) were chosen for comparison. In order to describe the effects of ageing on asphalt binders relaxation properties, the laboratory simulation of ageing using RTFOT and 3xRTFOT method was performed. For each binder were simultaneously conducted tests of needle penetration, softening point and elastic recovery. Selected bitumens were used for the production of asphalt mixtures. The low-temperature properties tests (TSRST) were performed for these mixtures, when the results were compared to the relaxation properties of binders determined in the DSR.
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A study of the vortex flow structures in heart compensation devices
Dokoupil, Michael ; Habán, Vladimír (referee) ; Fialová, Simona (advisor)
This master thesis is focused on study and description of flow in heart assistance devices. The aim was to evaluate the state of art for cardiac supports, selection of one device concept and improve the existing pump model. The types of heart replacements were evaluated in the research part of this work. Based on the research, an axial intraventricular pump was chosen for the simulation. The flow simulation was performed using computational fluid modeling. During the evaluation, special emphasis was placed on the description of vortex structures typical for cardiac support and analysis of hemolysis caused by the device.After selecting the optimization parameters, a design of a pump model was improved, which met the set optimization goals, especially the increase in efficiency and decrease of shear stresses. Towards the end of the work there was a discussion about the evaluation of hemolysis and vortex structures. In the end, particular possibilities for further improvement of the optimized pump were presented.
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Rheological properties of building binders in their fresh state
Hegrová, Michaela ; Rovnaník, Pavel (referee) ; Vyšvařil, Martin (advisor)
This thesis is devoted to the rheological properties of building binders. The theoretical part focuses on individual types of building binders, their rheological properties and basic parameters determinated during the rheological characterization of building binders. The practical part deals with the resultes obtained from the meansurements on a rotational rheometr using the geometry type of plate to plate. These results are subsequently evaluated.
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3D models of stress tensor
Stieber, Petr ; Pokorný, Přemysl (referee) ; Malášek, Jiří (advisor)
The aim of this bachelor´s thesis is to create 3D models of stress tensor. Mohr´s circles serve as a base for identification of size and direction of stress component. These are then used for the 3D modelling in software Rhinoceros. Final models in the form of colored areas show general, normal and shear stress for the individual states of stress.
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Design of boulder chute reconstruction in Lomná river at km 1,9
Hrabovský, Michal ; Golík,, Pavel (referee) ; Zachoval, Zbyněk (advisor)
The thesis deals the assessment of the resistance of the existing boulder chute in the river Lomná. At km 1,9 Boulder chute is located in the village Jablunkov. Surface resistance of boulder chute is assessed newly on the basis of non-dimensional shear stress for particle on arbitrarily sloped bed. The calculation of 2D flow was computed by HEC-RAS. On the assessment of resistance was proposed reconstruction of boulder chute.
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