|
|
Air flow in closed space
Jůza, Štěpán ; Uher, Pavel (referee) ; Rubina, Aleš (advisor)
Masters degree thesis with name “Air flow in closed space” in teoretical part describes air flow. Defined here basic types of flow including the flow in a closed space and the methods for the description of the air flow. The practical part deals with project eva-luation distribution of air conditioning system using CFD model. Next solves a second variant of air distribution and compare the changes that have occurred. The end of the practical part approaching the possibility of using CFD model for creating the quality environment maps and the possibility to create variants of calculating with changing levels of the supply air.
|
|
|
Innovation of the Cooling System of Rotating Electrical Machines using CFD Methods
Sikora, Michal ; Ondrůšek, Čestmír (referee) ; Kotrba,, Vít (referee) ; Sháněl, Martin (referee) ; Kratochvíl, Ctirad (advisor)
This thesis deal with design and implementation of innovative cooling method, intended primarily for medium-power synchronous generators. The main objective of this proposal is to remove the large heat exchanger connected to generator. This heat exchanger unduly increases the space requirements for the machine location. The proposed solution is to use a direct water-cooled stator. It is assumed that the rotor winding will be still cooled by air. Unlike current cooling system, the hot air from the rotor can be cooled in smaller cooler inside the generator. In this work are described methods which can be used for design of water cooling basic parameters, taking required temperatures into account. A small induction motor was selected for practical verification of the proposed cooling concept. This motor was modified into two variants - related to the old cooling of synchronous generators and related to the proposed solution. Both of these variants were measured and compared with each other. Subsequently, CFD models of these two variants were set up. Measured temperatures were used for debugging of models and identification of material properties of components of these machines. The final model of water-cooled variant also makes it possible to simulate the work of motor for higher performance and to determine the overload compared with the old cooling variant. Some knowledge and experience obtained from the small water-cooled induction machine were used in the design of water-cooling for large synchronous generator. In a similar way, CFD models of the old variant of cooling and proposed variant of water- cooling were created. Although these models were not verified by actual measurements on the generators, the results indicated that the application of water-cooling in this type of machine is appropriate and provides many benefits.
|
|
|
Influence of inlet hole position in hydrostatic bearing recess using CFD simulation
Androvič, Dominik ; Svoboda, Petr (referee) ; Michalec, Michal (advisor)
This bachelor thesis deals with the influence of inlet hole position in hydrostatic bearing recess in combination with lubricating film tilting using CFD simulation in ANSYS Fluent software. Before the investigation, encapsulation of hydrostatic bearing, CFD simulation and research of hydrostatic bearings was implemented. For investigation of ours the analytical reference model of an axial hydrostatic bearing based on recommended design parameters was created. The main parameters of interest maximal recess pressure and load capacity of bearing were emerged from analytic solution. Subsequently, the maximal recess pressure and load capacity of the bearing were computed using CFD simulation for selected position of the inlet hole and the lubricating film tilt. The results indicate that the load capacity of the bearing is decreasing with the increasing lubricating film tilt. However, in case of alteration of inlet hole position even combined with selected lubricating film tilts no significant changes in maximal recess pressure or load capacity of the bearing with changing in position of inlet hole has been observed. The obtained results might be used to improve the design of hydrostatic bearings.
|
|
|
Inner geometry optimization of flat-panel photobioreactor
Hlaváč, Ivan ; Babička Fialová, Dominika (referee) ; Rebej, Miroslav (advisor)
This master thesis focus on optimatization of flat-panel photobioreactor. The optimatization was performed using CFD models and Design of experiement. The CFD model used for the optimatizaion was before performing the experiment validated with real experiment data. Hydrodynamic parameters affecting microalgae yield were monitored during CFD calculations. They were: gas holdup, gas velocity, turbulent kinetic energy, dead zone ratio. interfacial area and shear stress.The photobioreactor with a stirrer and with vertical baffles, which were selected based on research, were compared. The higher values of hydrodynamic parameters were reached with a stirrer. Baffels were evaluated as more suitable for microalgae, which are more sensitive to shear stress.
|
|
|
Influence of inlet hole position in hydrostatic bearing recess using CFD simulation
Androvič, Dominik ; Svoboda, Petr (referee) ; Michalec, Michal (advisor)
This bachelor thesis deals with the influence of inlet hole position in hydrostatic bearing recess in combination with lubricating film tilting using CFD simulation in ANSYS Fluent software. Before the investigation, encapsulation of hydrostatic bearing, CFD simulation and research of hydrostatic bearings was implemented. For investigation of ours the analytical reference model of an axial hydrostatic bearing based on recommended design parameters was created. The main parameters of interest maximal recess pressure and load capacity of bearing were emerged from analytic solution. Subsequently, the maximal recess pressure and load capacity of the bearing were computed using CFD simulation for selected position of the inlet hole and the lubricating film tilt. The results indicate that the load capacity of the bearing is decreasing with the increasing lubricating film tilt. However, in case of alteration of inlet hole position even combined with selected lubricating film tilts no significant changes in maximal recess pressure or load capacity of the bearing with changing in position of inlet hole has been observed. The obtained results might be used to improve the design of hydrostatic bearings.
|
|
|
Multiphase Flow of Taylor Bubbles in Rectangular Microchannels.
Regner, Dominik
The aim of this work is to broaden our knowledge of the behavior of Taylor bubbles in a coflowing liquid inside flat microchannels with a high aspect ratio. The primary focus is put on the near-wall region, which is difficult to study both experimentally or numerically. The investigated quantities are the thickness of a liquid film separating the bubble from the microchannel wall, wall shear stress induced by the bubble movement, and the shape and velocity of the translating bubble.
Plný tet:  PDF
|
|
|
Three Dimensional CFD Model of a Single Rising Bubble in Stagnant Liquids.
Crha, Jakub
Two-phase (gas-liquid) flows are fundamental to wide range of chemical industrial processes such as absorption or distillation. Gaseous\nphase is mostly represented by rising bubble swarms through the liquid bulk. Physicochemical properties of the liquid and gaseous phases\ntogether with the bubble diameter and shape largely affect the bubble rise velocity, which defines the residence time of the bubble in the liquidbulk.1. Bubble behaviour can be studied experimentally, theoretically or most recently - using CFD solvers. These solvers are designed\nto numerically solve Navier-Stokes equations.
Plný tet: PDF
|
|
|
Air flow in closed space
Jůza, Štěpán ; Uher, Pavel (referee) ; Rubina, Aleš (advisor)
Masters degree thesis with name “Air flow in closed space” in teoretical part describes air flow. Defined here basic types of flow including the flow in a closed space and the methods for the description of the air flow. The practical part deals with project eva-luation distribution of air conditioning system using CFD model. Next solves a second variant of air distribution and compare the changes that have occurred. The end of the practical part approaching the possibility of using CFD model for creating the quality environment maps and the possibility to create variants of calculating with changing levels of the supply air.
|
|
|
Two phase flow of water and air, flat jet above the plate, jet sloping 75° and 90°
Říha, Zdeněk
The report contains CFD results and description of the two phase flow water and air. Water comes into the computational domain through\nsimplified nozzle which creates water flat jet with spraying angle c. 40o. The flat jet falls on the wall surface where flows along the surface plate in all directions (x,y mainly). The aim of the work is to show how the falling water flows on the wall surface with help of advanced CFD model. Two cases had been solved there with various jets sloping to the surface plate. The first case contains results with configuration of the geometry for the jet sloping 75o and second case contains results with configuration of the geometry for the jet sloping 90o, see enclosures 1 and 2. Given calculation had been done as steady state calculations.
|
|
|
Innovation of the Cooling System of Rotating Electrical Machines using CFD Methods
Sikora, Michal ; Kratochvíl, Ctirad (advisor)
This thesis deal with design and implementation of innovative cooling method, intended primarily for medium-power synchronous generators. The main objective of this proposal is to remove the large heat exchanger connected to generator. This heat exchanger unduly increases the space requirements for the machine location. The proposed solution is to use a direct water-cooled stator. It is assumed that the rotor winding will be still cooled by air. Unlike current cooling system, the hot air from the rotor can be cooled in smaller cooler inside the generator. In this work are described methods which can be used for design of water cooling basic parameters, taking required temperatures into account. A small induction motor was selected for practical verification of the proposed cooling concept. This motor was modified into two variants - related to the old cooling of synchronous generators and related to the proposed solution. Both of these variants were measured and compared with each other. Subsequently, CFD models of these two variants were set up. Measured temperatures were used for debugging of models and identification of material properties of components of these machines. The final model of water-cooled variant also makes it possible to simulate the work of motor for higher performance and to determine the overload compared with the old cooling variant. Some knowledge and experience obtained from the small water-cooled induction machine were used in the design of water-cooling for large synchronous generator. In a similar way, CFD models of the old variant of cooling and proposed variant of water- cooling were created. Although these models were not verified by actual measurements on the generators, the results indicated that the application of water-cooling in this type of machine is appropriate and provides many benefits.
|
guest ::
