|
| |
|
|
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.
|
|
|
Controlled generation of bubbles
Petráček, Michael ; Himr, Daniel (referee) ; Rudolf, Pavel (advisor)
This bachelor’s thesis describes behaviour of bubbles in supersaturated liquid. In the first part is described a mechanism of nucleation bubbles, their growth and motion in liquid. There are the results of experiment with a theoretical calculation compared in the second part.
|
|
|
Vortex breakdown
Lunda, Filip ; Rudolf, Pavel (referee) ; Urban, Ondřej (advisor)
The bachelor thesis deals with the vortex breakdown phenomenon. The first part focuses on a description of the vortex breakdown and its own characteristics. The next part deals with the theoretical description. After that, an enumaration of experimental devices used for observation of vortex breakdown follows. The last chapter contains information about control of this phenomenon.
|
|
| |
|
|
Cavitation erosion testing
Sochorec, Rostislav ; Moravec, Prokop (referee) ; Rudolf, Pavel (advisor)
The thesis is a literature survey of three most common methods of accelerated tests of cavitation erosion. These are cavitation induced by changing flow velocity in relatively conventional high-speed water tunnels, vibratory method which uses ultrasound to produce cavitation, and jets of liquid impacting surface of materials. In order to understand them, there is also a brief general introduction to the issue of cavitation and most important factors which can have effect on cavitation tests results.
|
|
|
Microfluidic circuit
Zeman, Radek ; Zemanová, Lucie (referee) ; Rudolf, Pavel (advisor)
Microfluidics is a science dealing with flow of a very small amounts of fluids and is mainly connected with medicine and biochemistry. One of a main problem, which this science is facing, is a difficult mixing of fluids due to occurrence of laminar flows. This bachelor thesis contains a design of a microfluidic circuit with Staggered herringbone microfluidic mixer and subsequent implementation of the experiment according to the performed design.
|
|
|
Eigenmodes of the swirling flow
Jízdný, Martin ; Pochylý, František (referee) ; Rudolf, Pavel (advisor)
This thesis deals with study of dynamics of the swirling flow. The swirling flow occurs frequently in hydraulic machinery (e.g., vortex rope in draft tube of the hydraulic turbine) and often influences operation of these machines. For this reason, sufficient knowledge regarding this characteristic flow is necessary for subsequent improvement of hydraulic machines. The theoretical part of this thesis contains description of flow instabilities and their manifestations, notably Kármán vortex street and vortex rope. In the next part, two methods are applied to these two transient flows in order to identify their specific dynamic properties. The first method, Fourier transform, enables to find frequencies of transient flow. The second method, proper orthogonal decomposition (POD), enables to identify planar or spatial eigenmodes of a specific swirling flow. Proper orthogonal decomposition is used in this thesis to identify planar eigenmodes of Kármán vortex street and spatial eigenmodes of vortex rope.
|
|
|
Integral sediment sampler
Zouhar, Josef ; Štigler, Jaroslav (referee) ; Rudolf, Pavel (advisor)
This thesis deals with analysis of flow inside integral SPM sampler. Flowing is described for one-phase flow and multi-phase flow (water-solid particles) approaches. Results of computational modeling and experimental modeling are compared. Experimental box was constructed and its construction is noticed. Methods of used computational and experimental modeling are described. Optimal computational model is recommended. The theme of this thesis was chosen in co-operation with Czech Geological Survey whitin the frame of project MŽP „SP/1b7/156/07“.
|
|
|
Flow structure and energy transformation in an elbow draft tube
Štefan, David ; Skoták, Aleš (referee) ; Rudolf, Pavel (advisor)
Draft tube is very important part of hydraulic turbines. Only optimum work together with turbine can bring highest performance of this machine set. Hence it is necessary to deal with character of flow in the draft tube for different operating conditions. Efficiency of the draft tube depends on many phenomena of flow. Observing these phenomena and finding their relation with energetic transformation in the draft tube is a suitable tool to judge quality of draft tube performance. Incorrect design of the draft tube can sometimes cause lower efficiency of whole machine set. The goal of this thesis is finding the main reasons causing draft tube efficiency drop for given operating conditions.
|
guest ::
RSS feed.