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Aircrafts auxiliary power units
Baran, Jan ; Klement, Josef (referee) ; Šplíchal, Miroslav (advisor)
This bachelors thesis describes concepts used airborne auxiliary power units (APU) with respect to the determination of the main advantages and difficultes in the construction of individual concepts. It also defines the trends in this area. Part of the thesis describes the possibility of using fuel cells as an energy source on board the airplane.
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Gas - steam cycle
Tóth, Richard ; Špiláček, Michal (referee) ; Kracík, Petr (advisor)
The Bachelor thesis „Gas-steam cycle“ explains the cycle from technical point and then its application in economic terms. At the beginning is explaind how gas turbine work and its application in Czech republic and World. In practical part are for real Gas-steam cycle Power Plant in simplified way calculated basic parameters and efficiency in full operation and operating only with gas turbines. The end contains a design of Heat recovery steam generator.
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Ideal cycle gas turbines
Bobčík, Marek ; Mauder, Tomáš (referee) ; Štětina, Josef (advisor)
The purpose of this bachelor thesis is to describe the basic characteristics of ideal cycle gas turbines. It deals with the derivation of basic formulae for thermal efficiency calculation. It then draws a comparison between the thermal efficiency of various types of heat cycles used for gas turbines.
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Thermal turbines
Tota, Lukáš ; Štelcl, Otakar (referee) ; Fiedler, Jan (advisor)
The bachelor thesis deals with thermal turbines. The first chapter contain history, with regard to the machines that preceded the turbines and the typical problems with the production of turbines. Then there is typology of steam and gas turbines. At the end of thesis there are examples illustrating the use of turbines in energy facilities.
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Dynamic Behavior of Laval Rotor
Nováková, Naděžda ; Hlavoň, Pavel (referee) ; Malenovský, Eduard (advisor)
The aim of this bachebor’s thesis is to specify self-frequency of model rotor system and verify that the system may be considered as Laval rotor. The natural frequency is obtained by calculating from the known relations for the circular rotor vibration. Verify that the model rotor system can be Laval rotor, is performed by using experimental measurements, which is determined in shaft deflection trajectory during gradually increasing speed. The measured values are then processed in program MATLAB. The results are compared with theory of Laval rotor
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Heat exchanger design for closed gas turbine cycle
Sklenář, Oldřich ; Bogdálek, Jan (referee) ; Šen, Hugo (advisor)
This bachelor’s thesis deals with determination of parameters of an experimental high temperature gas-cooled nuclear reactor cycle and a project of a regenerative heat exchanger designed to this cycle. The first part is dedicated to thermal cycles. This part includes an actual summary of high temperature reactors, an analysis of their cycles, a theory of closed gas turbine cycle and a calculation of elected cycle. The second part concerns a review of heat exchangers and gas coolers used for nuclear energy purposes and heat transfer theory. The main objective of this part is a calculation of heat exchanger from the conceptual, thermal, hydraulic and strength point of view including inclusion of analysis of this solution.
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Fractural based microstructural damane evaluation in Ni-based superalloy gas turbine blades
Tarafder, M. ; Dlouhý, Ivo ; Hore, S. ; Das, S. K.
A fractal based evaluation of microstructural damage in Ni based superalloy cast IN 738 LC used in gas turbine blades is presented in the paper. Non-destructive in-situ replica method was used without damaging the blades for the evaluation of microstructure. The theoretical life of the stator blades of the gas turbine, which was exposed to temperature varying between 1060°C to 1100°C, was approximately 100,000 hours. In order to assess the suitability of the stator blades after 50% of the service life, fractal based microstructural damage evaluation has been conducted. The fractal dimensions of the in situ metallographic images can be correlated to the progressive deterioration of hardness at various locations of the blades. The extent of damage is inversely proportional to the fractal dimension. For fractal dimension below 2.4, the material can be classified as substantially damaged.
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Microstructure and Anisotropy of Creep in Ti-46Al-2W-0.5Si Castings
Dlouhý, Antonín ; Kuchařová, Květa ; Svoboda, Milan ; Válek, Robert ; Březina, Josef
The present study investigates microstructure and creep behaviour of the cast alloy Ti-46A1-2W-0.5Si (at-%) at temperatures 700, 750 and 800°C and applied stresses between 250-420 MPa. Solidification of the alloy during precision casting is associated with two processes: (i) the growth of the [0001].alpha. oriented columnar grains from the mould wall into the cast interior and (ii) the enrichment of the central part of the cast with aluminium. The first process results in a fully lamellar microstructure where lamellae are preferentially oriented parallel to the cast surface. The second process contributes to the development of the duplex microstructure in the central part of the cast. It is shown that distinct microstructural types in different regions of the cast result in different creep strengths. Specimens taken from inside of the cast and oriented parallel to the cast bar axis exhibited the lowest creep strength while similarly oriented specimens cut from the fully lamellar region near the cast surface were the strongest. The third type of the creep specimens cut out of the central region of the cast and oriented perpendicular to the cast bar axis showed the intermediate creep strength. The observed variations of the creep strength are associated with the preferential orientation of the lamellas and with the fraction of equiaxed .gamma.-grains in the duplex regions of the cast.
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