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Aerodynamic components of passenger cars
Petrskovský, Adam ; Vančura, Jan (referee) ; Vondruš, Jan (advisor)
This bachelor thesis is focused on aerodynamics of the cars. Theories on aerodynamics characterizations as well as force exertions are presented here. Moreover, the influence of aerodynamics on fuel consumption and formation of harmful emissions is described. The thesis also provides a comprehensive overview of particular aerodynamic devices used on cars. Furthermore, CFD simulations of four aerodynamic devices on a simplified model of car are included. The results of these simulations are then evaluated and the respective aerodynamic devices are subsequently compared to find out which of them has contributed the most to the improvement of aerodynamic characteristics of the vehicle.
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Hydraulic turbine diffuser optimization using adjoint solver
Pham, Jakub ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
Tato práce se zabývá tvarovou optimalizací difuzoru vírového generátoru, který napodobuje oběžné kolo Francisovy turbíny. Optimalizace je založena na použití adjoint řešiče v programu ANSYS Fluent. Hlavním cílem bylo potlačení vírového copu v mimooptimálních režimech. Byla vytvořena metodika iterativní optimalizace pro adjungovaný řešič. Cílová funkce pro adjungovaný řešič byla zvolena s cílem minimalizovat moment hybnosti proudění kolem osy difuzoru. Byl představen a analyzován nový návrh difuzoru. Poté bylo provedeno srovnání chování vírového copu a proudového pole uvnitř nového a starého návrhu difuzoru. Bylo zjištěno, že optimalizace tvaru nevedla k žádnému významnému zlepšení chování vírového copu, přičemž energie vírového copu se pouze přenesla dále od náboje vírového generátoru. V závěru této práce byla formulována doporučení pro budoucí metody zmírnění vírového copu.
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Study of the Dissipation in Spiraling Vortical Structures
Štefan, David ; Drábková, Sylva (referee) ; Koutník,, Jiří (referee) ; Skoták, Aleš (referee) ; Rudolf, Pavel (advisor)
This work deals with study of swirling flows where the spiral vortical structure appears. The main relation is to flow seen in the draft tube cone of hydraulic turbines operated out of the design point (i.e. best efficiency point). In this cases large coherent vortex structure (vortex rope) appears and consequently high pressure pulsations are propagated to the whole machine system leading to possible restriction of turbine operation. This flow features are consequence of flow instability called vortex breakdown in case of Francis turbine operated at part load (flow rate lower than optimal one). The present study is carried out using simplified device of swirl generator in order to access similar flow conditions as can be found in real hydraulic turbines. Both the dynamic and dissipation effect of spiral vortex breakdown are investigated. The first part of thesis deals with spiral form of vortex breakdown. The experimentally measured velocity profiles (LDA) and wall static pressures are correlated with numerical simulations carried out using open-source CFD package OpenFOAM 2.2.2. The high speed camera recording of cavitating vortex core is used to obtain image ensemble for further post-processing. The dissipation effect of spiral vortex structure is in detail discussed based on computed flow fields. The second part of thesis is dedicated to the application of POD decomposition to the study of spatio-temporal features of spiral vortex dynamics. Firstly the POD is applied to the both the experimentally obtained image ensemble of cavitating vortex and numerically computed static pressure fields. Secondly the comprehensive analysis of spiral vortex mitigation effect by the axial water jet is analyzed. The collaborative study employing the swirl generator apparatus designed by the researchers from Politehnica University of Timisoara in Romania is performed and changes in spatio-temporal vortex dynamic are studied. In this study the numerical data (in a form of three-dimensional pressure and velocity fields) are obtained using commercial CFD software ANSYS Fluent R14.
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Experimental verification of ejector and creation of mathematical model.
Strmiska, Michal ; Štigler, Jaroslav (referee) ; Habán, Vladimír (advisor)
This diploma thesis deals with the area of ejectors. In the intoduction, an ejector is classed as an hydraulic machine. There is also an introduction of the principle and application of this machine there. The next part describes two different ways of calculation and there is a suggestion how to get characteristics, that were achieved by calculation in MS Excel, projected. The purpose of this diploma thesis is to confront this mathematical model with the experiment done in school laboratory at Kaplan department of hydraulic machines. The description of this experiment and the evaluation procedure of measured values is described in the final part of this diploma thesis.
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Optical design for LED luminaire
Oravčok, Ján ; Adamec, Michal (referee) ; Škoda, Jan (advisor)
The first part of the thesis is research, which deals with electric luminaires and especially their light-active parts. Subsequently is described the problem of a specific luminaire, which is used during the control of the surface structure of materials. The next part of the thesis deals with the simulation of the current luminaire and the simulations of the proposed solutions that eliminate the shortcomings of the luminaire. The conclusion of this thesis is the evaluation of the originally used luminaire and the benefits of the proposed solution, which showed the best results in the simulation.
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Experimental determination of the characteristics of air flow The distribution of elements
Ekl, Martin ; Rubinová, Olga (referee) ; Horák, Petr (advisor)
The thesis is aimed at the problem of the air distribution in buildings. The object of research is the concert hall. The thesis contains three different technical proposals and technical views of the microclimate concert hall. The microclimate’s solutions are focused on the air distribution in the hall. The part of the thesis is an experiment. The experiment continues on the one of the technical proposals. Its purpose is to determine the characteristics of air flowing from distribution element.
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The Pump with a Diffuser with Stochastic Blades (Runner and Diffuser)
Dobšáková, Lenka ; Melichar, Jan (referee) ; Veselý, Jindřich (referee) ; Haluza, Miloslav (advisor)
This doctoral thesis studies the non-uniform blade cascade for centrifugal pumps. Influence of non-uniform blade cascade is investigated on the impeller and diffuser. A non-uniform blading impeller of pumps in this doctoral thesis was examined in terms of influence on efficiency characteristic. The idea of using non-uniform blading is to obtain a flat efficiency characteristic. Then the centrifugal pump could be used on larger scale of power with achieving a sufficiently high efficiency. The work is based on experimental measurements and numerical simulations of non-uniform hydraulic pump components. Non-uniform impeller and the diffuser were newly designed for this research. A new measuring track of small submersible pumps was needed to design and build for measurements. Different pump combinations with conventional hydraulics on one working point and hydraulics with non-uniform were measured. All measurements were evaluated and characteristics of efficiency, head and power were obtained for each measured combination. Some of pump combinations (which were measured in experiment) were numerically simulated by program Ansys Fluent. Data needed to evaluate the characteristic of efficiency and specific energy were collected from each numerical simulation. A theoretical consideration concerns the influence of non-uniform blade cascade applied on diffuser. The suggestion how to decrease hydraulic losses in canals was done. The theoretical consideration how to make a flat efficiency characteristic was made.
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Air conditioning design in multifunctional sports hall
Navrátil, Radek ; Uher, Pavel (referee) ; Blasinski, Petr (advisor)
The diploma thesis deals with the design of air-conditioning equipment in the building of a multifunctional hall in Brno and also includes an experimental analysis of air flow. It consists of 3 parts. In the first part a theory of air distribution is elaborated. The second part deals with the analysis of air flow for different types of air diffusers and for one diffuser further looks for a simplified model. The last part of this work is focused on the design of air conditioning equipment in the assigned building, the multifunctional sports hall.
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Assessment of diffusion coefficient
Mikeš, Petr ; Schimmel, Jiří (referee) ; Míča, Ivan (advisor)
Most acoustic measurements and parameters provided by a manufacturer of acoustic elements, which are offering additional solutions to room acoustics as well as acoustic construction works, are mainly limited to the parameters associated with absorption of individual elements. Until now, these diffusional elements have been neglected. Diffusi- onal panels are used to e.g. eliminate direct reflection of sound waves to the listener or reflection of sound waves concentrated at one point. Combination of absorptive acoustic panels and diffusion elements results in a space that is customised to the submitter’s needs.
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