AN ANALYSIS OF THE LIQUID FILMS BREAK-UP USING THE COMPUTER VISION TECHNIQUE

The aim of this paper is to introduce a novel approach for analysing the droplet formation in a transonic flow. The method suggested in this work is based on the combination of the measured data from the wind tunnel by an optical measurement and image processing. A new wind tunnel was developed for the study of the liquid film atomization at high speed flows similar to ones that can be found in steam turbines. The coarse droplets in steam turbines are formed from the liquid films on the blades and inner casings. The coarse droplets formed on the stator blades don´t follow the bulk flow and collide with the following moving blades. These collisions cause erosion and corrosion processes, which have an unfavourable effect on the reliability and the efficiency of the low pressure stages of steam turbines. The tunnel is equipped with a standard instrumentation for the measurement of the flow properties and for the analysis of the size distribution of the droplets. Two measurement methods were used for the measurement of the size of the droplets, photogrammetry and light scattering. In this paper, the image processing of the captured images is discussed. The images were taken by a camera with a telecentric lens. The paper contains an assessment of three image processing methods used for the measurement of the droplet distribution by the light extinction. Moreover, the formation of the droplets is captured on the trailing edge of the profile in the flow. The results bring a new view on the formation of droplets at high speeds

Discontinuous Galerkin method for the solution of boundary-value problems in non-smooth domains

Tato práce se zabývá analýzou metody konečných prvků a nespojité Galerki- novy metody pro numerické řešení eliptické okrajové úlohy s nelineární Newtono- vou okrajovou podmínkou ve dvourozměrné polygonální oblasti. Slabé řešení ztrácí regularitu v okolí hraničních singularit, které se vyskytují v okolí rohů a kořenů slabého řešení na hranách. Hlavní pozornost se věnuje odhadům chyby. Ukazuje se, že řád konvergence není snížen nelinearitou, pokud je slabé řešení nenulové na větší části hranice. Pokud je slabé řešení nulové na celé hranici, pak nelinearita zpomaluje pouze konvergenci funkčních hodnot, ale ne konvergenci gradientu. Stejné výsledky jsou odvozeny pro přibližná řešení získaná pomocí numerické integrace. Odvozené výsledky jsou potvrzeny numerickými výpočty. 1This thesis is concerned with the analysis of the finite element method and the discontinuous Galerkin method for the numerical solution of an elliptic boundary value problem with a nonlinear Newton boundary condition in a two-dimensional polygonal domain. The weak solution loses regularity in a neighbourhood of boundary singularities, which may be at corners or at roots of the weak solution on edges. The main attention is paid to the study of error estimates. It turns out that the order of convergence is not dampened by the nonlinearity, if the weak solution is nonzero on a large part of the boundary. If the weak solution is zero on the whole boundary, the nonlinearity only slows down the convergence of the function values but not the convergence of the gradient. The same analysis is carried out for approximate solutions obtained with numerical integration. The theoretical results are verified by numerical experiments. 1Katedra numerické matematikyDepartment of Numerical MathematicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Air Conditioning Equipment for In-door Swimming-pool and its Rear Area

Import 29/09/2010Větrání, klimatizace a odvlhčování krytého bazénu : katedra energetiky - 361, Fakulta strojní VŠB – Technická univerzita Ostrava, 2010, Vedoucí: Lichý, M. Diplomová práce se zabývá návrhem větrání, klimatizace a odvlhčováním bazénového komlexu. V práci je zpracován návrh a technické zdůvodnění vzduchotechnického zařízení dle platných norem a vyhlášek. Sociální zařízení větráno a částečně klimatizováno. Bar větrán a klimatizován. Bazénový prostor větrán a odvlhčován. Řešení zahrnuje i úsporu energie zpětným získáváním tepla z odváděného vzduchu. V závěru bylo provedeno orientační vyčíslení investičních nákladů a přiložena je i výkresová dokumentace vzduchotechnického zařízení.Ventilation, air–conditioning system and dehumidifier in In-door Swimming-pool: Department of Power Engineering - 361, Faculty of Mechanical Engineering VŠB – Technical University of Ostrava, 2008, 51 p. Thesis, head: Lichý, M. Thesis deal with proposal ex-venting, air-conditioning plus dehumidification Swimming-poll spaces. In work is processed proposal plus technical warrant air conditioning arrangement according to valid norms plus public notice. Settlement ex-venting plus in part air- conditioned. Bar ex-venting plus air-conditioned. Swimming-pool space ex-venting plus dessication. Solving includes and energy conservation backward obtaining warm from exhaust air. At the close was effected orientation numeration capital expenditure plus enclosed is and design documentation air conditioning arrangement.361 - Katedra energetikyvelmi dobř

Measurement of O2 in the Combustion Chamber of Apulverized Coal Boiler

Operational measurements of the O2 concentration in the combustion chamber of a pulverized coal boiler are not yet common practice. Operators are generally satisfied with measuring the O2 concentration in the second pass of the boiler, usually behind the economizer, where a flue gas sample is extracted for analysis in a classical analyzer. A disadvantage of this approach is that there is a very weak relation between the measured value and the condition in specific locations in the fireplace, e.g. the function of the individual burners and the combustion process as a whole. A new extractionline was developed for measuring the O2 concentration in the combustion chamber. A planar lambda probe is used in this approach. The extraction line is designed to get outputs that can be used directly for diagnosis or management of the combustion in the boiler

MEASUREMENT OF O2 IN COMBUSTION CHAMBER WITH AN ANALYSIS OF THE BURN OUT RATIO

An aim of this experimental research work was to achieve more detailed information about the combustion process in pulverized coal boilers. An O2 analyser was developed and manufactured for the measurement of O2volumetric concentration directly in the combustion chamber. The volumetric concentration of O2 in the combustion chamber is important information about the burn out ratio, quality of combustion and the space distribution of the flame. The uniformity of the flame or the even distribution of the combustion parameters could be a possible way how to move to satisfy new emission limits. Measured parameters of the combustion process could be used for the control system of the boiler. The O2 analyser was manufactured for the permanent measurement with acceptable results. The measurement of the air excess ratio in the combustion chamber shows that for the left and right side of the combustion chamber could be highly non-uniform. For correct interpretation of the air excess ratio measured in the combustion chamber is necessary to know local amount of the unburnedcarbon in the position of the measurement. Therefore a new extraction line with an isokinetic probe was installed in the boiler for an extraction of the particles from the combustion chamber. The extracted sample was analysed in the laboratory and in the position where the combustion process should be terminated was measured from 3-12% of the flammable substance in the analysed sample

AN EXPERIMENTAL STUDY OF THE COARSE DROPLETS FORMATION

The paper introduces the first results from a new steam/air wind tunnel built in order to study the coarse water droplets in steam turbines and their formation. The wind tunnel was designed with the aim to have a testing facility with similar flow conditions for the study of liquid films as found in steam turbines. The tunnel is equipped with common devices for the measurement of the flow and for the analysis of the diameter distribution of the droplets. Two measurements methods were used for the measurement of the droplets size, photogrammetry and light scattering. The liquid film is artificially produced on an airfoil placed in the nozzle and liquid is pumped by a dosing pump on the surface of the airfoil. Coarse droplets formed from the liquid films have a negative effect on the reliability and efficiency of the turbines due to the erosion and corrosion by the droplets impact on the leading edges of the blades

Analysis of the FEM and DGM for an elliptic problem with a nonlinear Newton boundary condition

summary:The paper is concerned with the numerical analysis of an elliptic equation in a polygon with a nonlinear Newton boundary condition, discretized by the finite element or discontinuous Galerkin methods. Using the monotone operator theory, it is possible to prove the existence and uniqueness of the exact weak solution and the approximate solution. The main attention is paid to the study of error estimates. To this end, the regularity of the weak solution is investigated and it is shown that due to the boundary corner points, the solution looses regularity in a vicinity of these points. It comes out that the error estimation depends essentially on the opening angle of the corner points and on the parameter defining the nonlinear behaviour of the Newton boundary condition. Theoretical results are compared with numerical experiments confirming a nonstandard behaviour of error estimates