National Repository of Grey Literature 36 records found  beginprevious15 - 24nextend  jump to record: Search took 0.00 seconds. 
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.
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 design of swirl turbine for the concrete locality for ČEZ
Šebela, Radek ; Dobšáková, Lenka (referee) ; Haluza, Miloslav (advisor)
This thesis deals with the design of water turbine enabling optimal utilization of hydro-energetic potential of given location (barrage on Úpa river) chosen by ČEZ a.s. company. Moreover, the option of multi-unit layout is discussed. Because of the low-head profile of given location, the technology of swirl turbine in siphon configuration was chosen. Technology of swirl turbine presents new modification of Kaplan turbine with no need of guide vane. Swirl turbine is characterized by its high discharge and high speed. The main part of this thesis is focused on hydraulic design of the turbine.
Installations in the draft tube of the swirl turbine
Kilian, Ondřej ; Rudolf, Pavel (referee) ; Haluza, Miloslav (advisor)
Diploma thesis deals with design and exploration of installation in the draft tube of the swirl turbine. Use of the draft tube is defined in the first part, with illustration of energetical gain and efficiency of draft tube. Further the suitable shape of draft tube is studied by CFD computing. Design, research and evaluation of installation in the draft tube are solved in the main part.
Vortex rope mitigation of Francis turbine draft tube by shape optimization
Oberta, Brian ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
This master's thesis is aimed at the creation of shape optimization algorithm. The subject of optimization is a Francis turbine's draft tube in a sup-optimal operational regime. The objective of the shape optimization is the mitigation of vortex rope. The shape optimization is based on steady two-dimensional CFD simulations with usage of k- turbulency modelling. The results are validated by more advanced unsteady three-dimensional CFD simulations. As a part of shape optimization, this thesis ivestigates the possibilities of a simulation of vortex rope's manifestations with steady two-dimensional CFD models.
Hydraulic solution of the swirl turbine for locality of Rosenauer mill
Pavlíček, Tomáš ; Veselý, Jindřich (referee) ; Haluza, Miloslav (advisor)
This thesis focuses on the design of a swirl turbine for the site of Rosenauer Mill, where the gross hydraulic head HB is 1 m and the flow rate is Q is 1.6 m3/s. The beginning of the work is dedicated to microturbines and explains why a swirl turbine is suitable for this location. The procedure applied for developing the hydraulically active surfaces of the turbine is then presented. Firstly the design of the blades is based on analytical formulas, which are further refined using the CFX Ansys program. The turbine is closely affected by the inlet and draft tube, therefore their design is also included in this thesis. The hydraulic calculations yield the resulting parameters and characteristics of the designed turbine, calculated from the entire assembly using CFD computations. The final section of the work is devoted to the design of main structural components such as the gear, shaft, and bearings. The hydraulic design developed in this thesis serves as the basis for implementing the swirl turbine and constructing a small hydraulic power plant at the Rosenauer Mill.
The runner for the straight-flow turbine for small hydro power Sobotín
Žižka, Jakub ; Veselý, Jindřich (referee) ; Haluza, Miloslav (advisor)
The thesis deals with the problem of optimizing an existing unused turbine for use in a different location than the designed. The goal is to reduce the flow through the turbine by changing the runner geometry while increasing the head, with the least possible decrease in efficiency. The individual modifications of the hydraulic shape are based on the knowledge of the basic relations for the designing of hydrodynamic machines. Numerical fluid mechanics is a tool for validating the effect of individual adjustments. The hydraulic design of the new runner and draft tube of the axial propeller turbine with a fixed guide vanes is performed. Based on the CFD simulation, a universal turbine characteristic with a new hydraulic shape is compiled.
Influence of adjustable installations in the turbine draft tube on the characteristics and pressure pulsations
Šuráň, David ; Stareček, Jakub (referee) ; Haluza, Miloslav (advisor)
This master’s thesis deals with the draft tube and its optimization for various operating conditions. The research investigates the theoretical description and function of the draft tube and explains known methods of suppressing pressure pulsation so far. In the computational part, the author proposes a new method and designs optimal geometry of adjustable installations (ribs) for the draft tube. Finally, the comparison with the default geometry without ribs is performed.
Influence of difuser's opening angle on the dynamic properties of spiral vortex structure
Hazucha, Jan ; Kůrečka, Jan (referee) ; Štefan, David (advisor)
This master’s thesis deals with CFD simulation of spiral vortex structure in the diffuser of swirl generator. The objective of the thesis is to evaluate influence of change in diffuser opening angle on frequency and amplitude of pressure pulsation. All results are compared in charts which shows courses of frequencies and amplitudes along the diffuser. Two different turbulence models and several types of mesh were tested
Feasibility study of the pumped storage power station
Kratina, Jakub ; Duchan, David (referee) ; Dráb, Aleš (advisor)
Pumped storage power stations are an integral part of all power systems. At pre-sent, they represent perhaps the only option to accumulate more surplus electricity. It is also built as a proven regulatory element of the power system. The content of this bachelor thesis is a study of feasibility of the pumped storage power stationt (PVE Podlešín) in the Vaňov area. The introduction deals with the issue of pumped srorage power station. Then the design of a technical solution for the power plant construction follows. The main part of the study is the elaboration of drawing documentation and technical reports.

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