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Analysis of the turbine housing design in terms of heat leakage
Diakov, Jakub ; Lošák, Petr (referee) ; Vlach, Radek (advisor)
This diploma thesis deals with the judgment of usability of the topology optimisation of the Ansys Workbench program combined with thermo-mechanical fatigue and the non-linear material model of a turbine housing. The first part of the thesis includes research which serves for the purpose of understanding and for theoretical support of the practical part. The research part of the thesis at first gives reasons for the choice of the main aim of the thesis. The main aim of the thesis is the decrease of heat leak from the exhaust fumes due to the reason of the sooner combustion products processing and lower emissions production. The second chapter of the research analyses the construction and function of a turbocharger from the perspective of the geometry of the components and also from the perspective of the production and use of the components. The following chapter deals with the analysis of the energetic and thermal balance of the turbocharger. This chapter mentions the fundamental simplifications of the calculation problem and these simplifications are applied in the practical example. Next, the chapter analyses the thermo-mechanical fatigue, classification of the areas of fatigue and it also analyses the approaches used for the life expectancy predictions. The chapter of the research part deals with the selected areas of calculation and their theoretical basis. The last chapter analyses the fluid mechanics and the selected methods of the topology optimisation which are available in the selected calculation program. After the research part of the thesis, there follows the practical part which discusses a multiphysical example of the turbine housing optimisation from the perspective of heat leak and of the turbine housing being exposed to the thermo-mechanical fatigue. The practical part which is composed of several steps is based on the CFD analysis and this analysis is used for the purpose of gaining thermal conditions in order to calculate the transient thermal analysis. Out of the outcomes of the coupled transient thermal analysis, there is used the spatial temperature field which as a result of the expansivity of the material causes non-homogenous stress on the turbine housing. The practical part has an individual chapter dedicated to the usability of the topological optimisation in different types of tasks. One of the parts of this chapter includes is a suggestion of the methodology for determination of voltage limitation for the selected type of topological optimisation. The penultimate chapter in the practical part is dedicated to the topological optimisation of the turbine housing on the basis of the preceding voltage analysis and determined limitation. The last chapter includes performed validation of the optimised shape of the housing after the geometry is adjusted. The validation is performed from the perspective of steady state temperature of the output combustion products, of speed of heating of the optimised geometry and from the perspective of the comparison of the life expectancy determined in the thermo-mechanical fatigue. At the end of thesis, there are included conclusions discussed and suggested, scope for improvement and possibilities for continuation of further research.
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Using Calculix computing environment to solve problems of solid mechanics
Lukáš, Jan ; Lošák, Petr (referee) ; Vosynek, Petr (advisor)
Submitted bachelor thesis is focused on a solution of solid mechanics problems in a computing environment of the Calculix program. In the opening of the thesis there are briefly described theoretical foundations of finite element method. Subsequently there are analyzed particular parts of the program environment of Calculix. The main part of the thesis deals with solutions of three selected problems of solid mechanics. There are three different types of analyzes: static structural, modal dynamic and explicit dynamic. In the first assignment there is discovered deformation and stress in a fixed compressed squared timber. The second assignment deals with modal properties of the fixed squared timber. The last assignment discovers effect of loading velocity on the deformation of fixed compressed squared timber. In the conclusion there are briefly evaluated advantages and disadvantages of the Calculix program and there are compared solutions of the Calculix program and commercial program.
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Standardized procedure of the machine tool adjustment for change of the machined part type
Nedoma, Tomáš ; Tuna, Jaroslav (referee) ; Lošák, Petr (advisor)
The bachelor thesis at hand is dealing with standardized procedure of machine adjustment in process of machined rail type change in Bosch Diesel s.r.o. Jihlava. In the thesis, procedures of external adjustment of preparations that clamp workpieces into machining centers and overall procedure of machine adjustment are described. The elaborated standardized procedures are included in instruction manuals, which are used by workers of the company for machine adjustments. These “manuals” shall minimize occurrence of defective steps in the adjustment process and prevent their interchange. Mistakes based in incorrect procedure of the workers lead to prolongation of the time necessary for machine adjustment in process of change of machined type by up to hundreds of minutes per month. Bosch Diesel s.r.o. has adopted these instruction manuals and thanks to them shall save couple of tens of thousands euro per year.
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Simulation of Noise Emitted by a Single-stage Gearbox
Motl, Daniel ; Hadaš, Zdeněk (referee) ; Lošák, Petr (advisor)
The level of noise and vibration of gearboxes is one of the most important parameters for today´s customers. This thesis deals with mathematical acoustic behavior modelling and its contribution to the gearbox design using finite element method. The process is presented at three computations models. Two of those were validated with experimental measurement. Acoustic analysis were performed with software FFT ACTRAN.
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The use of hydraulic disc brakes for road bikes
Dvořáková, Barbora ; Lošák, Petr (referee) ; Šebek, František (advisor)
This bachelor's thesis is focused on the usage of hydraulic disc brakes on road bikes. The thesis is divided into two parts. In the first part, there is a research focused on differences in construction and properties of hydraulic disc brakes in comparison with rim brakes. The main emphasis is placed on evaluating all advantages and disad-vantages of the hydraulic disc brakes in comparison with rim brakes. Evaluation is conducted both from the functional point of view and user point of view with taking different requirements of both recreational level cyclist and professional cyclist into account. The aim of the second part is the numerical simulation of loading of the frame and fork for both types of brakes. The goal of this part is an overall assessment of suitability of hydraulic disc brakes for the road bikes.
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Analysis of the rotor packet prestress on the rotor critical speed
Lekeš, Filip ; Huzlík, Rostislav (referee) ; Lošák, Petr (advisor)
The presented diploma thesis deals with the modeling of the rotor packet in dynamic calculations and analysis of the influence of the packing pressing force on the critical speed of the electric motor. The thesis can be divided into three main parts. The first part discusses the current level of rotor packet modeling in dynamic calculations and also deals with analytical theories for subsequent experimental tests. The second part describes the implementation of two experiments to determine the equivalent modulus of elasticity. The first experiment is a four-point bending test and the second is an experimental modal analysis. The third part is used for comparing the results obtained from experimental tests and describes the calculation of the critical speed of the rotor package pressed on the shaft by the finite element method.
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Comparison of modal properties of steam turbine impeller with blades of different lengths
Havlásek, Michal ; Chromek, Lukáš (referee) ; Lošák, Petr (advisor)
The presented master's thesis deals with the safety assessment of several variants of the impeller with different blades length. The motivation for creating this thesis is to find the solution of the problem situation which is characterized by the breakdown of the steam turbine impeller with blades length of 30mm. As confirmed in this thesis, the impeller with blades length of 30mm is operated in the resonance. Likewise, according to the technical standard ČSN EN ISO 10437 its operation is not safe. As the correction action for the problem situation solving is proposed the prolongation of the impeller's blades. The safety is detected for six variants of impeller with dierent blades length. For each variant, there is executed a modal analysis and its results are drawn up into the Campbell diagram. On the basis of this diagram, the safety of individual components is evaluated. The last part of the masters thesis concerns with the examination of the influence of blades length on the modal properties of the impeller.
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