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Influence of Centrifugal Compressor Acoustic and Operating Parameters by Stator Geometry Modifications
Vacula, Jiří ; Vítek, Oldřich (referee) ; Babák, Martin (referee) ; Novotný, Pavel (advisor)
The increasing demands on the operational capabilities of rotating machines are mutually reflected in the ever-increasing computational capabilities. This makes it possible to analyse very detailed aerodynamic phenomena and to investigate the detailed effects of lesser-known aerodynamic principles. The standard aerodynamic design of a centrifugal compressor consists of an open impeller containing a smooth stator; however, the shape of the stator also contributes to the resulting parameters of a rotating machine. Thus, in this paper, the effect of stator geometry is first analysed qualitatively by analytical methods based on the analysis of the Navier-Stokes equation. Next, the influence of stator geometry is investigated by a Computational Fluid Dynamics (CFD) tool using circumferential casing treatment. The experimentally measured circumferential grooving of GT15 compressor shows that the quality of the treated surface can have a significant effect on the resulting performance of the rotating machine. Another measured casing treatment variant of the GTD2056 compressor shows an increase in efficiency of 0.5% and a marginal effect on aerodynamic noise. The relationship between the efficiency increases and losses is analysed using a viscous dissipation function that directly points to the influence of the flow field due to the geometric modifications of the stator and is shown to be largely conclusive for describing the losses in the impeller region.
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Strength Analysis of Turbocharger Rotor of Stationary Internal Combustion Engine
Kejval, Dan ; Kudláček, Petr (referee) ; Novotný, Pavel (advisor)
Turbocharger rotors are highly stressed components exposed to significant thermo-mechanical loads. This thesis provides a literature review of this issue concerning turbocharger rotors and focuses on the thermal field analysis and structural analysis of the turbocharger rotor of a stationary internal combustion engine under different steady-state operating conditions, especially under maximum thermo-mechanical load. The analysis was conducted using Ansys Mechanical software, which allows for the calculation of the thermal field as well as the identification and evaluation of critical areas of the rotor using the finite element method. The result of the thesis is an assessment of the rotor's safety, including the risk of loosening the rings preloaded on the rotor shaft.
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Methodology for Identification of Turbocharger Noise and Vibration Sources
Valenta, Otakar ; Kocman, František (referee) ; Novotný, Pavel (advisor)
Malfunctions of machines and machine components are usually accompanied by an increase in vibration and noise. By analysing these vibrations and noises, it is possible to assess their overall condition, diagnose problems and detect possible anomalies and malfunctions. For a successful and practical analysis of turbocharger sounds and vibrations, it is necessary to distinguish turbocharger sounds and vibrations from ambient noise and obtain their characteristics in real time. In the thesis there is performed detailed analysis of the turbocharger noises and vibrations, the sources and reasons for the occurrence of individual vibrations and noises are described, their dependencies on the characteristics of the turbocharger and their allocation to the frequency band. In Matlab Simulink environment, a mobile phone software is developed to provide real-time analysis of the turbocharger sound and to display the probable cause of the turbocharger noises and failure in a graphical interface. The software was tested using sound recordings of Garrett GTD2056 and PBST TCR16 turbocharger sounds. The software is developed using a student version of Matlab and may serve as a foundation for the development of commercial software applications.
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Improvement of turbocharger inlet manifold parameters
Kula, Štěpán ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
The bachelor thesis deals with the design of a new elbow geometry to reduce the pressure drop in the inlet suction pipe of a turbocharger compressor. At the beginning of the thesis there is a description of the fluid flow and hydraulics losses that result in pressure loss in the pipe. Next, possible methods by which the shape of the piping can be optimized are described. The last, main section deals with the actual optimization of the elbow using the manual method and the Adaptive Single-Objective method, which succeeded in reducing the pressure losses and improving the outlet flow profile.
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Flow and heat transfer between the rear side of a turbocharger turbine wheel and the bearing housing
Kalugina, Marina ; Novotný, Pavel (referee) ; Vacula, Jiří (advisor)
The objective of the bachelor’s thesis is to determine the heat balance at the point between the back of the turbine wheel and the bearing housing. The findings concerning the fluid flow and heat transfer in small channels of a rotor-stator system were derived from previously published works. The main focus of this study is the heat exchange between the heated air and the rotor wall. Calculations are applied to the turbine wheel of a real turbocharger to investigate convective heat flow at different local radii. Furthermore, a thermal resistance system is implemented in the stator section to explore potential methods for improving heat dissipation.
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Implementation of automatic controls of electrical signals for the monitoring system of the Temelín Nuclear Power Plant
Mareček, Michal ; Novotný, Pavel (referee) ; Drápela, Jiří (advisor)
This bachelor's thesis deals with individual electrical devices for self-consumption, focusing on production blocks of the nuclear power plant Temelín, which are continuously monitored by the superior electrical monitoring system NEMES. A key element is the description of the areas of power output and self-consumption of the electrical blocks of the power plant, including the NEMES system, necessary for the design of automatic checks of the measured electrical signals reliability. Knowledge of the device concept and operating modes is crucial to the successful implementation of NEMES system signal checks in logical links and in view of deviations from the band of operating values. The subject of the thesis is to propose limits for all main electrical equipment together with blocking conditions for performing automatic checks of the reliability of the monitored signals by the NEMES system, which will be of great benefit to the end user - the operator of the Temelín nuclear power plant.
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Topological optimisation of the turbocharger electric actuator bracket
Směšný, Jan ; Kudláček, Petr (referee) ; Novotný, Pavel (advisor)
Topology optimization utilizes mathematical methods to develop the most efficient components in terms of mechanical properties and weight. Nowadays, it is a commonly used tool for designing components not only in the automotive, aerospace, and space industries. This work deals with the topological optimization of a metal bracket used to attach an electric actuator to a turbocharger. The turbocharger assembly is subjected to external influences, the most significant of which are vibrations from the engine. The program Ansys Workbench was used for modal and topology optimization calculations. The goal of the optimization was to minimize weight and maximize the natural frequency. The optimization takes into account a simple manufacturing method using conventional techniques (shearing & bending), which will remain the same for the optimized component. Additional care is taken to ensure, that the natural frequency of the bracket-actuator system is above the excitation frequency from the engine. The final optimization revealed that by appropriately removing material, the component's weight can be reduced by 22% without significantly degrading its dynamic properties.
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Analysis of software solutions for particle motion in moving fluids
Bohuslav, Marek ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
The issue of particle motion in moving fluids is a more frequently discussed topic in the automotive industry concerning the new EURO 7 emission standards. Requirements include particles from brakes, tire wear and exhaust gases and their limitations. To limit them, it is possible to capture them and for that, the behaviour of the particles needs to be predicted. Particle behaviour can be simulated using the right software, which requires an understanding of flow physics to be set up. The bachelor's thesis offers a complete overview of the CFD principles of flow and particle motion in fluids. In the second part, the thesis provides an overview and analysis of usable software for particle flow solutions with examples of their practical use in this matter. The third part focuses on the demonstration of particle flow in the numerical simulation in the software Ansys CFX, particularly in a simulation of particle motion in oil in a slide bearing. The demonstration includes an analysis of the results and provides useful insights and tips for creating a simulation in Ansys CFX.
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Modelling the Oil Lubrication System of Turbocharger
Breckl, Lukáš ; Hliník, Juraj (referee) ; Novotný, Pavel (advisor)
The diploma thesis contains a research part focused on turbocharger construction, engine lubrication system and turbocharger, basic physical properties of lubricating oils and hydrodynamics. The purpose of this thesis is to create analytical and CFD computational model of turbocharger lubrication system. Output pressures and the loss of specific energy are determined.
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Lubricant Gap Shape Optimization of the Hydrodynamic Thrust Bearing
Ochulo, Ikechi ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
The objective of this Master's thesis is to find, using genetic algorithm (GA), an optimal profile for lubricating gap of a thrust bearing of a turbocharger. Compared to the analytical profile, the optimal profile is expected to have minimized friction for an equivalent load capacity. Friction minimization is one way to increase the efficiency of the thrust bearing; it reduces the friction losses in the bearing. An initial problem was given: a thrust bearing with Load capacity 1000 N, inner and outer radii of 30mm and 60mm respectively, rotor speed of 45000 rpm and angle of running surface of $0.5^0$. Lubricant properties were also provided for the initial problem: oil density of $ 840 kg/m^3$, dynamic viscosity $(\eta)$ of 0.01 Pa.s With this data, the numerical solution of the Reynolds equation was computed using MATLAB. To obtain more information, the minimum lubricating gap thickness was also computed using MATLAB. With this information, the shape of the analytical profile, and its characteristics were found. The analytical profile was then used a guide to create a general profile. The general profile thus obtained is then optimized using GA. The characteristics of the generated profile is then computed and compared to that of the analytical profile.
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