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CFD simulation of vortex structure in the Francis turbine draft tube at part load operating point - comparison with measurements
Neděla, Jiří ; Urban, Ondřej (referee) ; Štefan, David (advisor)
This master's thesis deals with simulation of vortex structure which is created in the draft tube of Francis turbine, at part load flow conditions. The main objective is to get the most accurate results from the calculations, using the student license of Ansys Fluent 19.1. The results from the calculations are compared with the experiment under the Francis-99 project. Mainlly in terms of dynamic properties of vortex rope – aplitude and frequency of pressure pulsations. Additionaly the time-averaged velocity profiles are compared. I used the test-case provided by NTNU – Norwegian University of Science and Technology under the Francis-99 workshop series.
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Flow control in a hydraulic turbine draft tube
Litera, Jiří ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
Hydraulic energy is one of the most important sources in the world for electricity production. Nowadays the trend is to limit the production of the electricity from fossil fuels and to protect the environment. The main idea is to use more renewable energy sources such as wind and solar energy. Unfortunately, these alternative sources are strongly dependent on current weather conditions, which causes the instability of the electrical grid. Luckily pumped storage and hydraulic power plants provide the solution. However, it requires an extension of the operating range of the hydraulic machines. For that reason, the water turbines now operate over and extended range of regimes, that can be quite far from the best efficiency point. Hence two types of unstable two-phase flows in the Francis turbine draft tube occur: part load overload. This diploma’s thesis is focused on the Francis turbine operating at the part load. During part load conditions the helical vortex rope is being developed in the draft tube, it causes pressure pulsation and it can lead to the hydro-acoustic resonance, which damages the elements of the power plant. The aim is to eliminate the pulsation by jet control of the swirling flow in the draft tube. In the diploma’s thesis, various approaches to jet control of the flow in conical diffuser are tested using the computational fluid dynamics.
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The pumped-storage hydro power plant Dlouhé Stráně
Jurová, Kristýna ; Roub, Radek (advisor) ; Bureš, Luděk (referee)
The Bc. thesis deals with the topic of The Dlouhe Strane Pumped-Storage Hydro Power Station ( termín viz: https://www.cez.cz/en/power-plants-and-environment/hydraulic-power-plants/dlouhe-strane.html, that is being referred as the most the most powerful pumped-storage in the Czech Republic.
The theoretical part of the thesis contains not only basic information about hydro energy, but also the basic classification of water turbines, a description of their work functions and usage. Further, the thesis describes the construction of the three most used water turbines. The work also mentions the basic classification of hydro power plants. The core of this work contains the issue itself of The Dlouhe Strane Pumped-Storage Hydro Power Station. The thesis mentions the difficulties with the construction process in its beginning and also other difficulties, as the construction works of the Station went along.
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Vortex rope for overload operation of Francis turbine
Kozák, Jiří ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
This master's thesis deals with CFD simulation of vortex rope in the elbow draft tube for overload operation of Francis turbine. The main objective of the thesis is to compare results of the CFD simulations of the original elbow draft tube with a derived straight cone draft tube considering volume and the shape of the cavitation region and dynamic flow characteristic. Results of the 3D simulations are also compared with axi-symmetric simulations, which reduce demands for computing time and power.
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Francis turbine runner design
Žák, Radim ; Veselý, Jindřich (referee) ; Haluza, Miloslav (advisor)
The graduation theses are focused on reconstruction of the small hydro-electric power station Harta. Design of detailed runner blading based on the parameters of the given location is part of the reconstruction. Model of the duplex Francis turbine for cast manufacturing is result of the graduation theses. Numerical description of the model was carried out using SolidWorks software.
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Water turbines and them use
Machát, Pavel ; Sloupenský, Zdeněk (referee) ; Himr, Daniel (advisor)
This bachelor´s thesis deals with the problems of water turbines. It contains basic division of water turbines, description of their oparations and possibilities of their utilizations. Further this thesis focuses on description of the three most used turbines i.e. Francis´s, Kaplan´s and Pelton´s turbines. As one component of this work there are also mentioned essential relations required for selection of proper type of turbine in dependency on speed, slope and flow rate.
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