|
| |
|
| |
|
| |
|
|
The turbine regulation of the small hydro-powerplants
Horký, Jiljí ; Dobrovolný, Martin (referee) ; Stareček, Jakub (advisor)
This bachelor thesis deals with the regulation of water turbines in small-hydro power plants. The first chapter presents the basic theory of this issue. In the next following two chapters, the characteristics of individual types of turbines, their construction and construction of control mechanisms are introduced. With the help of velocity triangles is shown, how the flow conditions are changing during the work of control mechanisms and what influence the control has on the hydraulic machine.
|
|
|
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.
|
|
|
Numerical simulation of rotor-stator interaction (RSI) of Francis turbine
Machoň, Matěj ; Skoták, Aleš (referee) ; Štefan, David (advisor)
The master's thesis deals with the numerical simulation of rotor-stator interaction (RSI) of Francis turbine. In the selected operating point of the machine, the pressure amplitudes belonging to RSI frequencies are evaluated in various pressure sensors and compared with available experimental data. Various simplifications of the simulation, namely using Transient Blade Row Modelling, are done and their impact on results is investigated. Lastly the modal analysis with acoustics elements present is performed to obtain the eigenfrequencies and mode shapes of the runner submerged into water to be able to conclude, if the resonance occured.
|
|
|
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.
|
|
|
Feasibility study of the pumped storage power station
Bolek, Marek ; Špano, Miroslav (referee) ; Dráb, Aleš (advisor)
The aim of this bachelor thesis is to create a study that deals with the construction of the machine cavern of the shaft-type pumped-storage power plant containing 4 machine sets of the Reverse Francis Trubine with underground penstocks and short discharge tunnels, located in the area of a quay in Vaňov in the Ústí nad Labem District. The introduction deals with the pumped-storage power plants in general. The following chapter focuses on the assessment of the locality of interest. The final part contains a proposal of a structural-technological design of the machine cavern by means of a technical report, a design of the spiral case and documentation of the structure by means of drawings.
|
|
|
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.
|
|
|
The influence of number and position of stay vanes on characteristic of Francis turbine
Mraček, Pavel ; Skoták, Aleš (referee) ; Haluza, Miloslav (advisor)
The thesis deals with the influence of the number and position of stay vanes on the characteristic of a Francis turbine. The main objective is to find the most hydraulically advantageous configuration by CFD simulations. It was important for this work to use comparable methods, in particular the same turbulence model and computational grid. The output of the thesis is a comparison of hydraulic losses for different configurations of the position of guide vanes and number of stay vanes.
|
guest ::
