National Repository of Grey Literature 120 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Car chassis diffuser
Kindl, Albert ; Balko, Marek (referee) ; Rudolf, Pavel (advisor)
Improving a car's aerodynamic properties can save fuel, increase range, or improve speed and handling. To achieve this, aerodynamic modifications and improvements are proposed to cars. The aim of this thesis is to describe a diffuser on an automotive chassis. The focus is mainly on the effect of its divergence angle on drag and lift. These dependencies are investigated on a simplified car model using CFD simulation in Ansys Fluent. The research section discusses the diffuser flow and losses, other important aerodynamic features and the importance of the diffuser in Formula 1 and passenger cars. The results of the thesis show the significant effect of the diffuser on the downforce and drag of the vehicle and indicate the important position of this element in the future of the automotive industry.
Dissolved gas effect on hydrodynamic cavitation
Piňos, Ondřej ; Fialová, Simona (referee) ; Rudolf, Pavel (advisor)
Thesis is focused on hydrodynamic cavitation in gas saturated liquid flowing in microfluidic circuit with Ventruri noozle. Thesis describes theoretical base in fields of: gas saturation of liquids, cavitation inception, diffusion mechanisms and cavitation collapses. In practical part experiment on microfluidic circuit was done. In pressurised tank liquid was saturated by gas, after letting the mixture into noozle we observed beginning of cavitation by acoustic and visual way. Inception of cavitation was also observed by -\sigma graphs. With increasing pressure in tank we observed developed cavitation, its persistivity was compared with increasing amount of gas in liquid. Measured values are supported by theoretical part of thesis. There was nonconformity in comparison of demineralised water and tap water saturated by air, where demineralised water cavitated during higher cavitation numbers for saturating pressures of 4 and 6 kPa. Further research could focus on undersaturated water as well as on better control of water properties, especially on number of nuclei within.
Energy recuperation in water delivery system
Pavlík, Šimon ; Rudolf, Pavel (referee) ; Himr, Daniel (advisor)
The thesis deals with the use of energy potential in water supply networks and is divided into three main parts. The first part describes the characteristic elements of the water supply network and analyses the energy potential of the Nové Bránice water supply system, which was identified in the location of the pressure reducing valve. The second chapter is devoted to designing algorithm according to which a system of energy recovery - a pump in turbine mode is designed. The statistical analysis is counted as well. In this chapter, the theory of pump in turbine mode operation and the prediction theory of turbine characteristic estimation are presented. The final part of the thesis is devoted to creating a water network model in Epanet 2.2. In one day simulations the current state of the system with a pressure reducing valve is compared with the system including the proposed pump in turbine mode.
Wind tunnels for passenger cars
Fabríci, Tomáš ; Zeman, Radek (referee) ; Rudolf, Pavel (advisor)
The bachelor thesis is focused on a wind tunnel usage in the field of automotive industry. Nowadays, they are still the significant part in vehicle aerodynamics research. Specifically, at determining power actuating on vehicle, flow visualization, aero-acoustic measurements. Considering personal vehicles, reducing the drag and reducing the consumption are being accentuated. Aero-acoustic measurements are becoming more and more popular for improvement of driving comfort. Air-flow quality in wind tunnels directly affects the accuracy of the mentioned measurements. The effort is to minimize the accidental turbulence and reach uniform flow quality. Perfect quality of the air-flow will never be reached even though there is an optimal proposal of all sections from which the wind tunnels consist. Very often, we must be satisfied with the accepted flow quality according to the application. However, the progress in the field of computing modeling has reduced the time spent in wind tunnels and moreover it has saved finances. Currently, there is close cooperation between them to reach the best results possible.
Vortex rope mitigation of Francis turbine draft tube by shape optimization
Oberta, Brian ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
This master's thesis is aimed at the creation of shape optimization algorithm. The subject of optimization is a Francis turbine's draft tube in a sup-optimal operational regime. The objective of the shape optimization is the mitigation of vortex rope. The shape optimization is based on steady two-dimensional CFD simulations with usage of k- turbulency modelling. The results are validated by more advanced unsteady three-dimensional CFD simulations. As a part of shape optimization, this thesis ivestigates the possibilities of a simulation of vortex rope's manifestations with steady two-dimensional CFD models.
Machine learning in water machine diagnostics
Šebek, Denis ; Rudolf, Pavel (referee) ; Habán, Vladimír (advisor)
The thesis focuses on utilizing high-frequency measurement methods for measuring pressure, sound, and acoustic emission, and their application in machine learning for detecting operational states in water machinery. This thesis aims to propose a machine-learning approach capable of evaluating cavitation, flow conditions, and faults based on the collected data. The first part of the thesis discusses the theoretical introduction to selected high-frequency measurement methods and provides a basic introduction to machine learning. The second part describes the experimental setup, including data preprocessing and the implementation of a neural network. In the conclusion, the individual results are evaluated and compared.
Disc friction loss in centrifugal pumps and hydraulic turbines
Zemanová, Lucie ; Kozubková, Milada (referee) ; Sedlář, Milan (referee) ; Rudolf, Pavel (advisor)
Dizertační práce je zaměřena na výzkum proudění v mezidiskových spárách hydraulických strojů s důrazem na čerpadla s nízkými specifickými otáčkami. Navzdory tomu, že tekutina v mezidiskových prostorách čerpadel zaujímá velmi malý objem, může výrazně ovlivnit proudění v celém stroji. To má následně vliv na provoz, charakteristiky a celkovou účinnost, zvlášť v případě čerpadel s nízkými specifickými otáčkami, protože stav proudění určuje vznikající diskové ztráty. Rovněž ovlivňuje rozložení tlaku a tím výslednou axiální sílu. Porozumění proudění v mezidiskových spárách je zatím omezené, současné poznatky vychází z teorie odvozené pro značně zjednodušený případ disku rotujícího v hladké válcové spáře. Použitelnost pro popis proudění ve skutečných hydraulických strojích je diskutabilní. Za účelem výzkumu proudění v reálném odstředivém čerpadle bylo navrženo a sestaveno experimentální zařízení umožňující pozorování proudění v zadní mezidiskové spáře pomocí optických metod, měření krouticího momentu a vznikající axiální síly. Také byla popsána metodika pro numerické simulace tohoto druhu proudění umožňující podchytit nestability a vírové struktury. Numerické simulace vhodně doplňují experimentální měření, rozšiřují rozmezí studovaných provozních podmínek a pomáhají popsat jevy, které by šlo měřením jen obtížně odhalit.
Reduced order model of the swirling flow
Urban, Ondřej ; SUSAN-RESIGA, Romeo Florin (referee) ; Uruba, Václav (referee) ; Rudolf, Pavel (advisor)
Tato dizertační práce je zaměřená na studium vírového copu. Za tímto účelem byl navržen nový vírový generátor umožňující regulaci intenzity zavíření. Chování vírového copu bylo studováno jak numericky, tak experimentálně. Byly použity numerické simulace zachycující i část energetické kaskády turbulentního proudění, dále byly navrženy metody vizualizace dat založené na objemovém renderování a byla testována různá vírová kritéria. Také bylo studováno několik metod dekompozice proudových polí. Nakonec byly navrženy metody pro extrakci kvaziperiodických módů. S využitím těchto metod byl sestaven redukovaný model pro daný rozsah provozních bodů.
Digital twin concept for hydraulic machines
Klement, Jan ; Burda, Radim (referee) ; Rudolf, Pavel (advisor)
The term “Digital twin” is associated with Industry 4.0. It is a projection of an object into a virtual environment, which enables to predict behaviour and explore the existing behaviour. In engineering, such objects can be components, machines, or entire companies. Subsequently, Digital twin helps to determine the most suitable operation depending on the conditions. This thesis deals with the possibilities of digital twin. Subsequently, it describes the current state of turbomachinery, concentrating in particular on hydraulic machines in the field of Digital twin. The final part of the thesis describes the concept for creating a Digital twin for a centrifugal pump.
Dialysis pump
Švagera, Roman ; Rudolf, Pavel (referee) ; Fialová, Simona (advisor)
Dialysis is still very important treatment process today which needs to be constantly improved. This thesis focuses on the development of a pump for dialysis units, specifically on the pressure pulsations reduction in the rotary peristaltic pump. Using experiments, the problem of peristaltic pumps is explained. With the computational modelling there are proposed design modifications leading to the pressure pulsations reduction.

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