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Last stage steam turbine
Šabacký, Filip ; Brettschneider, Bohuslav (referee) ; Fiedler, Jan (advisor)
This Master’s thesis deals with a pre-calculation of a steam condensation turbine on a blading mid diameter. The governing stage is solved as a A-turbine wheel, impulse blading. Multistage blading is solved as a reacion stage by ca/u method. Further, detailed calculation of last stage with a twisted blade is made. Thesis contains comparision of obtained results with a results provided by contracting company. Final part of thesis deals with a design of sectional shape of a turbine blade.
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Design of orifice plates for steam for high pressure difference
Gajdůšek, Tomáš ; Himr, Daniel (referee) ; Habán, Vladimír (advisor)
The work deals with the design of a system of orifices for high pressure difference. The task of this work is to design a device for controlled discharge of steam-gas mixture from a volume compensator with an overpressure of 12,27 MPa to a tank with an overpressure of 0,02 MPa at a constant mass flow of 40 kg/h. The first part of the thesis contains the theory and also the basic principles of calculations. In the next part of the work, the theoretical properties of flow, such as the speed of sound in wet steam, are determined. This knowledge then serves the main goal of the work, namely to design a system of orifices to release steam-gas mixture from the volume compensator.
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Numerical simulation of transonic flow of wet steam
Nettl, Tomáš ; Dolejší, Vít (advisor) ; Feistauer, Miloslav (referee)
This thesis is concerned on the simulation of wet steam flow using discontinuous Galerkin method. Wet steam flow equations consist of Naviere-Stokes equations for compressible flow and Hill's equations for condensation of water vapor. The first part of this thesis describes the mathematical formulation of wet steam model and the derivation of Hill's equations. The model equations are discretized with the aid of discontinuous Galerkin method and backward difference formula which leads to implicit scheme represented by nonlinear algebraic system. This system is solved using Newton-like method. The derived scheme was implemented in program ADGFEM which is used for solving non-stationary convective-diffusive problems. The numerical results are presented in the last part of this thesis. 1
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Design of orifice plates for steam for high pressure difference
Gajdůšek, Tomáš ; Himr, Daniel (referee) ; Habán, Vladimír (advisor)
The work deals with the design of a system of orifices for high pressure difference. The task of this work is to design a device for controlled discharge of steam-gas mixture from a volume compensator with an overpressure of 12,27 MPa to a tank with an overpressure of 0,02 MPa at a constant mass flow of 40 kg/h. The first part of the thesis contains the theory and also the basic principles of calculations. In the next part of the work, the theoretical properties of flow, such as the speed of sound in wet steam, are determined. This knowledge then serves the main goal of the work, namely to design a system of orifices to release steam-gas mixture from the volume compensator.
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Experimental research of heterogeneous nuclei in expansion chamber
Bartoš, O. ; Hrubý, Jan ; Kolovratník, M.
An expansion chamber has been developed to investigate experimentally homogeneous and heterogeneous nucleation processes in steam. A chamber design allows to measure in the laboratory but also in power plants using the steam withdrawn from the steam turbine. The purpose of the device is to provide a new approach to study the physics of non-equilibrium wet steam formation, which is one of the factors limiting the efficiency and reliability of steam turbines. The expanded steam or a known mixture of steam with a non-condensable gas rapidly expands in the expansion chamber. Due to adiabatic cooling, the temperature drops below the actual dew point. When reaching a sufficiently high supersaturation, droplets are nucleated. By tuning the supersaturation in the so-called nucleation pulse, particles of various size ranges can be activated. This fact is used in the present study to measure the aerosol particles present in the air. Homogeneous nucleation was negligible in this case. The experiment demonstrates the functionality of the device, data acquisition system and data evaluation methods.
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Consistency of empirical corrections of the classical nucleation theory for nucleation in steam with nucleation experiments and molecular simulations
Hrubý, Jan ; Duška, Michal ; Němec, Tomáš ; Kolovratník, M.
We compare experimental nucleation rates for water vapour in various carrier gases, nucleation rates deduced from empirical adjustments of the classical nucleation theory (CNT) earlier developed to reproduce pressure and optical data for condensing steam flows in converging-diverging nozzles and turbine stages, and ucleation rates obtained from molecular simulations. Results of original molecular dynamic simulations for TIP4P/2005 force field in the NVE conditions are provided. New experimental nucleation rate data sets are generated based on empirical CNT corrections by Valha and Nedbal (1980) and by Petr and Kolovratník (2011). Correction of the CNT for non-isothermal nucleation conditions is applied to experimental, simulated and the derived experimental data. The derived experimental\nnucleation rate data follow a similar temperature trend as the nucleation rate data for water vapour in carrier gases at lower temperatures. The ratio of observed nucleation rates to CNT predictions decreases more steeply with temperature than the empirical correction by Wölk et al. (2002). Ratios of nucleation rates computed from molecular simulations to CNT predictions do not show a significant temperature trend.
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Numerical simulation of transonic flow of wet steam
Nettl, Tomáš ; Dolejší, Vít (advisor) ; Feistauer, Miloslav (referee)
This thesis is concerned on the simulation of wet steam flow using discontinuous Galerkin method. Wet steam flow equations consist of Naviere-Stokes equations for compressible flow and Hill's equations for condensation of water vapor. The first part of this thesis describes the mathematical formulation of wet steam model and the derivation of Hill's equations. The model equations are discretized with the aid of discontinuous Galerkin method and backward difference formula which leads to implicit scheme represented by nonlinear algebraic system. This system is solved using Newton-like method. The derived scheme was implemented in program ADGFEM which is used for solving non-stationary convective-diffusive problems. The numerical results are presented in the last part of this thesis. 1
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Last stage steam turbine
Šabacký, Filip ; Brettschneider, Bohuslav (referee) ; Fiedler, Jan (advisor)
This Master’s thesis deals with a pre-calculation of a steam condensation turbine on a blading mid diameter. The governing stage is solved as a A-turbine wheel, impulse blading. Multistage blading is solved as a reacion stage by ca/u method. Further, detailed calculation of last stage with a twisted blade is made. Thesis contains comparision of obtained results with a results provided by contracting company. Final part of thesis deals with a design of sectional shape of a turbine blade.
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Numerické řešení dvoufázového proudění při interakci statoru a rotoru
Halama, Jan ; Fořt, Jaroslav
This work deals with a numerical solution of 2D unsteady compressible flow of mixture of vapor and condensed droplets in axial turbine stage. Governing equations consist of the Euler equations for the mixture and the transport equations for integral parameters of droplet spectra (Hill's approximation). The computational domain is created by several stator and rotor blade passages in order to get simple periodicity condition. The stator and the rotor parts are connected by 'interface cells', proposed originally by Giles. Numerical method is based on the Strang splitting method, convection part is solved by the finite volume cell-vertex method based on the Lax-Wendroff scheme with artificial viscosity term and condensation part is solved by two-stage explicit Runge-Kutta method. The first numerical results are discussed.
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