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Slip factor of the hydrodynamic pumps
Duda, Petr ; Archalous, Jakub (referee) ; Klas, Roman (advisor)
Bachelor thesis contains basic information about the hydrodynamic pumps. It describes the specific energy for an infinite number of very thin blade and following corrections to the finite number of blades. Part of this work is dedicated to all-weather resulting in Blade to blade channel and their effect on specific energy pump. There are illustrated by calculations of correction factors of individual authors and finally corrections are made on real three impeller wheels with a comparison of different methods.
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Inlet recirculation of centrifugal pump
Heinz, Pavel ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
This diploma thesis deals with the phenomenon appearing in hydrodynamic pumps at the sub-optimal flow rate. This phenomenon is inlet recirculation, which is an undesirable phenomenon in the suction of the pump. This recirculation causes cavitation, pressure pulsations and may cause clogging of the suction line. The main goal of the diploma thesis is CFD simulation for the recirculation mode, identification of the flow phenomena, and designs of possible measures to suppress inlet recirculation.
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Analysis of the Velocity and Pressure Fields of the Liquid Using Curvilinear Coordinates
Stejskal, Jiří ; Kozubková, Milada (referee) ; Kučera,, Radek (referee) ; Veselý, Jindřich (referee) ; Pochylý, František (advisor)
This work introduces a new method of hydraulic design of a centrifugal pump impeller. This method is based on a geometrical approach employing curvilinear coordinates that are used to formulate both the axisymmetrical flow model in a meridional shape and the final model of flow in a blade cascade taking into account the full 3D shape of the impeller blade. The solution to this model then directly provides the guidelines for shaping the impeller blade in order to suppress the secondary flows, thus increasing the impeller efficiency, which is demonstrated on a real impeller design case. The partial differential equations describing the flow in the blade cascade are numerically solved piecewise on each particular stream surface, which leads to a significant reduction of computational time.
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Low specific speed pump working in turbine mode
Bezdíček, Jiří ; Moravec, Prokop (referee) ; Štefan, David (advisor)
The use of the pump in turbine mode is an evolving area. For this reason, research of less standard pumps from the edges of the specific speed spectrum is suitable for this purpose. This diploma thesis was focused on the influence of splitter blades on the exclusively turbine mode of a low specific speed pump. CFD calculations of the pump were performed, considering the sidewall gaps between the stator and the rotor. CFD served not only to obtain turbine characteristics but also to describe the flow and analysis of other phenomena, such as volumetric efficiency or hydraulic forces.
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Modification of pump for turbine regime
Jahn, Jan ; Veselý, Jindřich (referee) ; Haluza, Miloslav (advisor)
Hydraulic design of a hydrodynamic machine is designed to achieve a high value of energy transformation efficiency. Pumps and turbines have some different typical features in hydraulic design. With the aid of computational fluid dynamics, adjustments of the hydraulic parts of a standard centrifugal pump are assessed with the aim to increase hydraulic efficiency of the pump running as turbine. The impeller, volute casing and added draft tube are discussed.
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Slip factor of the hydrodynamic pumps
Chromek, Lukáš ; Himr, Daniel (referee) ; Klas, Roman (advisor)
This bachelor thesis deals with the initial draft of an impeller wheel, determination of its specific energy that has a pump with infinite number of impeller blades and following correction to real specific energy of an impeller wheel pump with finite number of blades. The correction will be performed using different methods by various authors and some of the methods will also be compared during the calculation of specific energy and discharge head of pump of several real impeller wheels. Then the thesis goes on to deal with some of the effects arising from the flow of fluid in the impeller wheel that often have negative influence on above-mentioned specific energy. At the end of the thesis, there will be brief abstract on problems of the correction, simulation, and analysis of flow in a blade channel using CFD software.
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CFD simulation of centrifugal pump working as a turbine (PaT) - influence of impeller side wall gaps on simulation results
Tomšej, Radek ; Zemanová, Lucie (referee) ; Štefan, David (advisor)
This master‘s thesis deals with a centrifugal pump running in reverse (turbine) mode, often called “pump-as-turbine”. The introduction lists basic principles and information about the direct (pump) and reverse modes. Several methodologies for predicting reverse operating point and efficiency evolution are used and compared with simulation results. Using CFD simulations, results obtained with simplified (excluding impeller side wall gaps) and complete geometry (including impeller side wall gaps) are assessed. Furthermore, the results of impeller trimming are evaluated with an aim to find the maximum power and efficiency. Impeller side wall gaps effect is analyzed in terms of friction torque and power loss.
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Computational modeling of cavitation characteristic curve of radial centrifugal pump
Leischner, Jakub ; Chabannes, Lilian (referee) ; Štefan, David (advisor)
Tato práce se zabývá jedním z nejčastějších problémů spojených s provozem radiální odstředivých čerpadel mimo optimální podmínky - kavitací. Její příčiny a vliv jsou vysvětleny a shrnuty společně s popisem hlavních částí čerpadel a simulačních metod výpočtového modelování proudění. K vyhodnocení vlivů kavitace na provozní parametry čerpadla jsou použita data z experimentálního měření a vytvořeného CFD modelu. Hlavní charakteristiky čerpadla, jako dopravní výška a účinnost, jsou srovnány ve 4 bodech zahrnujících rozmezí od návrhového bodu až po nevhodný provozní režim při poklesu dopravní výšky o více než 3 %. Jako doplněk je z výsledků CFD simulací vyhodnocen objem páry vznikající v oběžném kole a frekvence pulzací působících sil.
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