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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.
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CFD model of mixture gas flow in the vacuum column 12T-70102, existing state of internals
Říha, Zdeněk
The report contains description of fluid flow for case with existing state of the column 12T -70102. Vapor flow was mainly calculated in the above mentioned geometry. In last iteration the liquid droplet (diameter 0,3mm) were injected into the geometry through the nozzle 12, see enclosure in the report. Introductory section of the enclosuere contains pictures with geometry and boundary conditions description, See figure G1. Then, slice plan follows, see figure G2. Next pictures show distribution of pressure and velocity on given slices. Pictures at the end of the enclosure show path-lines distribution and droplets particle traces distribution in the solved geometry.
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CFD model of mixture gas flow in the vacuum column D-6501, adjusted EVH and tray
Říha, Zdeněk
The report contains CFD results and description of the gas mixture flow in the vacuum column D-6501 with adjusted internals against last calculated case, see [1]. Two rotationally opposite (swirl) input nozzles S1 and S2 (ID 0,835m) create main input of vapour into the vacuum column. There are two enhanced vapour horn (EVH) distributor, for given input nozzle (S1, S2) separately. Enhanced vapour horn makes redistribution of vapour leaded from above mentioned nozzles. There also is next input of vapor given by bottom striping section. The inner diameter of the column is 7,464m and solved domain has height c. 15m. Aim of the calculation is to show distribution of calculated variables (velocity, pressure, density, etc.) on given slices. Mainly, we would like to know if the distribution of velocity is sufficiently uniform at the input into the packing bed SECTION “B”
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CFD model of multiphase flow in the abrasive water jet tool
Říha, Zdeněk
The possibility of using CFD fluid flow modeling in area of tools with abrasive water jet is described in the paper. The correct function of such tool is based on proper setting of multiphase flow of water, air and solid particles in the inner space of the tool. The multiphase fluid flow numerical simulation can provide information which show relation between the geometry and the flow field. Then, this stable CFD model of multiphase flow creates key to design of the tool able to work with higher efficiency.
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