Labyrinth seal force estimates are important to the prediction of the stability of turbomachinery. The force prediction methods fall into several categories: experiments, bulk flow analysis, and finite volume analysis. Finite volume analysis can be split into two subcategories: self-developed and commercial. In this research, a commercial computational fluid dynamics (CFD) program called ANSYS-CFX was used to predict the forces generated in a labyrinth seal whirling at specified speeds. The results were compared to data from VT-FAST, a bulk flow code, and TASCflow, another commercial CFD program. It was shown that there were discrepancies among the results, and several hypotheses were made as to the reason for these discrepancies. Additionally, ANSYS-CFX was used to study the effect of labyrinth seal eccentricity ratio on the resultant force generated. It was shown that the radial force component within the seal behaved linearly with respect to eccentricity ratio. However, the tangential force component had no distinguishable relationship with the eccentricity ratio. It was hypothesized that the lack of a relationship was caused by the small fluctuations in the inlet swirl. Although the inlet swirl varied very little at each eccentricity ratio, it was shown there was a relationship between the tangential force and inlet swirl. / Master of Science

Zur Verringerung von Schadstoffemissionen werden in Kaminöfen oft Keramikfilter integriert, die Staub und Ruß aus dem Abgas entfernen sollen. Die Filter beeinflussen jedoch die strömungsmechanischen, energetischen und chemischen Vorgänge im Feuerraum. Für die Auslegung und die praktische Anwendung der Filter ist die Kenntnis der Einflussgrößen und deren Umfang nötig. Mit Hilfe von experimentellen und numerischen Untersuchungen wurden die Stoff- und Energietransportvorgänge von zwei Kaminöfen charakterisiert. Zur Bestimmung der Massenabnahme von Holzscheiten kam eine neue, praktisch leicht umsetzbare Methode, basierend auf einer Schockkühlung mit flüssigem Stickstoff, zum Einsatz. Parallel dazu wurde die Massenabnahme der Holzscheite mit Hilfe einer Online-Massenbestimmung mittels Waage aufgezeichnet und ein Verfahren zur Bestimmung der Abbrandkinetik entwickelt. Die Schwierigkeiten der messtechnischen Erfassung und Auswertung der instationären Vorgänge wurden dargestellt und diskutiert. Für die zwei Kaminöfen sind numerische Simulationen mit der Software ANSYS CFX erstellt worden, die weitgehend auf realen Geometrien beruhen. Vergleichende null- und eindimensionale Simulationen mit unterschiedlichen Reaktionsmechanismen und gasförmigen Brennstoffen wurden realisiert und hinsichtlich ihrer Eignung für die Berechnung von Kaminöfen untersucht. Nach erfolgter Validierung wurde ein parametrisches Simulationsmodell eines Kaminofens erstellt. Mit diesem wurde eine Parameterstudie zur Untersuchung der Veränderung der Zielgrößen Heizleistung, Kohlenmonoxid- und Rußkonzentration sowie Gesamt- und Sekundärluftmassenstrom in Abhängigkeit der Parameter durchgeführt.

This project uses CFD analysis to make design choices for a facility to test flow accelerated lead corrosion erosion of steel samples. Two conceptual designs are considered and compared through mechanical and physical criteria. The first design uses steel samples on stationary plates next to rotating discs. The second design has the steel samples on the rotating disc. The first design is considered unfeasible due to high pressure gradients in the system and a high power requirement from the motor. The second design removes the issue of high pressure gradients and can decrease the motor requirements. This design is selected for further analysis and discussion of manufacturing. / Detta projekt använder CFD-analys för att göra designval för en anläggning för att testa flödesaccelererad blykorrosionserosion av stålprover. Två konceptuella konstruktioner beaktas och jämförs genom mekaniska och fysiska kriterier. Den första designen använder stålprover på stationära plattor bredvid roterande skivor. Den andra designen har stålproverna på den roterande skivan. Den första konstruktionen anses vara ogenomförbar på grund av höga tryckgradienter i systemet och ett högt effektbehov från motorn. Den andra designen tar bort problemet med höga tryckgradienter och kan minska motorkraven. Denna design är vald för vidare analys och diskussion om tillverkning.

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-04T20:52:13Z No. of bitstreams: 1 JÉSSICA BARBOSA DA SILVA DO NASCIMENTO - DISSERTAÇÃO (PPGEM) 2017.pdf: 5634263 bytes, checksum: 929da71867fefc79201bbfa0a102a100 (MD5) / Made available in DSpace on 2018-04-04T20:52:13Z (GMT). No. of bitstreams: 1 JÉSSICA BARBOSA DA SILVA DO NASCIMENTO - DISSERTAÇÃO (PPGEM) 2017.pdf: 5634263 bytes, checksum: 929da71867fefc79201bbfa0a102a100 (MD5) Previous issue date: 2017-08-17 / Capes / Os separadores são equipamentos utilizados no processamento primário da indústria do petróleo com o objetivo de separar a mistura multifásica proveniente dos poços produtores. O trabalho avaliou o efeito dos dispositivos internos do vaso separador sobre a dinâmica do escoamento no processo de separação gás/óleo. Foi definido uma modelagem matemática com base na dinâmica de fluidos computacional (CFD) do separador horizontal bifásico. Adotou-se a abordagem Euleriana-Euleriana, considerando o modelo de mistura, disponibilizado no software Ansys CFX 15.0. O domínio consiste em um separador horizontal cilíndrico constituído de uma placa porosa que o divide em duas regiões: a região de separação primária, contendo três dispositivos internos (um defletor e duas chicanas) e a região de decantação. Foi gerada uma malha numérica empregando elementos tetraédricos, para a discretização das equações de conservação de massa, momento linear e de turbulência k padrão usando o método dos volumes finitos. Assumiu-se o escoamento em regimes permanente e transiente, isotérmico, com propriedades dos fluidos constantes e das forças interfaciais foram consideradas apenas as forças de arraste. Os resultados dos campos vetoriais de velocidade, assim como a fração volumétrica das fases indicam que a dinâmica do escoamento é fortemente dependente dos dispositivos internos. Na região de separação primária observou-se um alto nível de mistura causada pela turbulência gerada pelo impacto dos fluidos sobre a placa defletora posicionada imediatamente após a seção de entrada. A placa porosa possibilitou uma redução da turbulência dos fluidos, causada pela resistência do meio poroso ao escoamento. / The separators are equipments used in the primary processing of the petroleum industry to separate the multiphase mixture from the producing wells. The work evaluated the effect of the internal devices of the separator vessel on the flow dynamics in the gas/oil separation process. A mathematical model was defined based on computational fluid dynamics (CFD) of the horizontal two-phase separator. The Eulerian-Eulerian approach was adopted, considering the mixture model, available in Ansys CFX 15.0 software. The domain consists of a horizontal cylindrical separator consisting of a porous plate that divides it in to two regions: the primary separation, containing three internal devices (one deflector plate and two baffles) and the settling region. A numerical grid was generated employing tetrahedral elements, for the discretization of the mass conservation, linear momentum and k standard turbulence equations using the finite volume method. Isothermal flow with constant fluid properties in both steady state and transient regimes were assumed, and, from the interfacial forces, only the drag forces were considered. The velocity vector field results as well as the volumetric fraction of the phases indicate that the flow dynamics are strongly dependent on the internal devices. In the primary separation region, a high-level of mixing was observed due to the turbulence generated by the impact of the fluids on a deflector plate positioned immediately after the inlet section. The porous plate allowed a reduction of the turbulence of the fluids, caused by the resistance of the porous medium to the flow.

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-03-23T18:34:30Z No. of bitstreams: 1 DANIEL CESAR DE MACEDO CAVALCANTE – TESE (PPGEP) 2017.pdf: 5981753 bytes, checksum: 7cb1bc84364b7e8874a0a5bd64ac28f9 (MD5) / Made available in DSpace on 2018-03-23T18:34:30Z (GMT). No. of bitstreams: 1 DANIEL CESAR DE MACEDO CAVALCANTE – TESE (PPGEP) 2017.pdf: 5981753 bytes, checksum: 7cb1bc84364b7e8874a0a5bd64ac28f9 (MD5) Previous issue date: 2017-08-24 / Capes / Os hidrociclones convencionais são equipamentos versáteis, devido a elevada capacidade de processamento, baixo custo de manutenção. Vários são os estudos que visam alterar a estrutura típica do hidrociclone convencional de modo alterar seu desempenho e objetivo. Assim surgiu os hidrociclones filtrantes no qual se diferencia do hidrociclone convencional pela substituição da parede cônica ou cilíndrica por uma membrana porosa. Durante o funcionamento desse separador, além das correntes tradicionalmente observadas (alimentação, underflow e overflow), há uma corrente líquida proveniente do processo de filtração, normalmente denominado filtrado. O presente trabalho propõe estudar hidrociclones filtrantes baseados no trabalho de Façanha (2012), a partir do estudo numérico do processo de separação água/partícula sólida realizado com auxílio do “software” comercial ANSYS CFX® Release 15.0. O modelo matemático usado considera escoamento tridimensional, turbulento, estacionário, baseado na abordagem Euleriana-Euleriana e modelo de turbulência SST “Shear Stress Transport”. Foram avaliados estudos da dinâmica do escoamento, Efeito da porosidade, efeito da permeabilidade e efeito da matriz porosa. Os resultados demonstram que a vazão do filtrado é menor em relação as outras saídas, altera o escoamento no interior do hidrociclone filtrante tanto em relação a porosidade, permeabilidade e efeito da posição do meio filtrante. O aumento da porosidade e permeabilidade alterou a distribuição de pressão, razão do líquido e eficiência total no interior do hidrociclo cilíndrico filtrante. / Conventional hydrocyclones are versatile equipment due to high processing capacity and low maintenance costs. Several studies are aimed at changing the typical structure of conventional hydrocyclone in order to alter its performance and purpose. In this way the hydrocyclones filtering in which it differs from the conventional hydrocyclone by the replacement of the conical or cylindrical wall by a porous membrane. During the operation of this separator, in addition to the traditionally observed currents (feed, underflow and overflow), there is a liquid stream coming from the filtration process, usually called filtrate. The present work proposes to study filtering hydrocyclones based on the work of Façanha (2012), based on the numerical study of the water / solid particle separation process performed with the commercial software ANSYS CFX® Release 15.0. The mathematical model used considers three-dimensional, turbulent, stationary flow, based on the Eulerian-Eulerian approach and SST turbulence model "Shear Stress Transport". Studies of flow dynamics, porosity effect, permeability effect and porous matrix effect were evaluated. The results show that the flow rate of the filtrate is lower in relation to the other outlets, it changes the flow inside the filter hydrocyclone in relation to the porosity, permeability and effect of the position of the filter medium. The increase in porosity and permeability altered the pressure distribution, liquid ratio and total efficiency inside the filter cylindrical hydrocyclones.

Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-26T15:19:43Z No. of bitstreams: 1 BRUNO FERREIRA SILVA -DISSERTAÇÃO (PPGEM) 2016.pdf: 3315035 bytes, checksum: 915092a23718ba159ff32b574a8fb04e (MD5) / Made available in DSpace on 2018-04-26T15:19:43Z (GMT). No. of bitstreams: 1 BRUNO FERREIRA SILVA -DISSERTAÇÃO (PPGEM) 2016.pdf: 3315035 bytes, checksum: 915092a23718ba159ff32b574a8fb04e (MD5) Previous issue date: 2016-02-29 / Capes / Na indústria de petróleo, o transporte de óleos pesados em oleodutos requer altas potências de bombeamento devido a sua alta viscosidade, sendo este um dos inconvenientes na produção de óleos dessa natureza; surge assim a necessidade de desenvolvimento de novas tecnologias que otimize tais processos. Uma técnica economicamente viável e que pode ser usada, é o core anular flow, onde uma camada de água é responsável pela lubrificação do óleo que escoa no centro do duto. Desse modo, o presente trabalho apresenta um estudo energético e hidrodinâmico envolvendo o transporte de óleos pesados e água em dutos de conexões curvadas, através de simulação numérica via software ANSYS CFX® Release 15.0. Foi utilizado um modelo matemático que considera o modelo de mistura para tratar o escoamento bifásico águaóleo pesado, tridimensional, transiente e isotérmico, assumindo regime laminar para fase óleo e turbulento para a fase água adotando o modelo de turbulência k . Uma análise energética envolvendo as bombas também foi realizada. Resultados de campos de pressão, velocidade e fração volumétrica para as duas fases são apresentados e analisados. Verifica-se que o uso da técnica core-flow proporciona uma redução de 95,4% na queda de pressão por fricção comparado ao escoamento monofásico de óleo pesado, e que o desligamento e repartida das bombas de óleo e água afetam a queda de pressão por fricção. / In the oil industry, the transport of heavy oils in pipelines requires high power pumping due to its high viscosity, which is one of the drawbacks in oils production of this nature, thus emerge a need to develop new technologies that optimize such processes. An economically viable technique that can be used is the core annular flow, where a water layer is responsible for oil lubrication flowing in the center of the duct. In this way, this work presents an energy and hydrodinamic study of the heavy oils transportation in curved connections by numerical simulation via software ANSYS CFX® Release 15.0. It used a mathematical model that considers the mixture model to treat heavy oil-water two-phase flow, three-dimensional, transient and isothermal, assuming laminar flow to oil phase and turbulent flow to water phase, using k-ε turbulence model. An energy analysis involving pumps was performed. Results of pressure, velocity and volumetric fraction fields for the two phases are show and analysed. It was verified that the use of core-flow technique has decreased in 95.4% friction pressure drop as compared to monophase heavy oil flow and that stop-and-go from the oil and water pumps affect pressure drop by friction

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.

The aim of this master´s thesis was to model the fan for the induction motor, and then to solve this model using Ansys CFX in the terms of flow, when considering the different speeds of rotation of the rotor. The introduction of this work is dedicated to basic terms and definitions from spheres of fluid flow, cooling of the electrical machines, especially to the cooling of the asynchronous machine. There is also attention paid to losses in this machine. Finally, there is modeled radial fan and an air gap of specified induction machine. By using Ansys CFX the flow, which passes from the fan into the air gap, is analyzed.

The thesis is focused on possibilities of asynchronous motors cooling with use of simulation at ANSYS Workbench program. It is divided into two parts. The first part deals with analyses of cooling medium circulation through ventilator and cooling medium circulation on the motor surface. As a result of the analyses is air speed distribution and air pressure representation. The second part of the thesis includes simulation of motor temperature rise both with cooling and without cooling at Ansys Workbench application together with temperature measurement of real asynchronous motor in the laboratory. For cooling purposes air circulation was used. The goal of my research is comparison of the computing results with the measured results.

With growing awareness and necessity for the world to move towards more sustainable (energy saving) forms of power generation, focus on the commercial use of Organic Rankine Cycle (ORC) turbine systems has subsequently increased in turn. ORC systems with their modular design can thus help in recovering heat, obtained as a byproduct from a variety of industrial processes, and thereby increase their overall system efficiency. As with conventional turbine systems, methods to improve their performance is an avenue that is still being actively researched on today. The various sources of losses in a turbine have thus been looked into, while prioritizing the literature study to factors that result in losses associated with the leakage flow over the blade tip. The purpose of this study is to develop a working methodology to investigate factors that affect the tip leakage loss in a small scale ORC turbine. The model and associated data used for comparison is based on an existing system, whose design has been provided by Againity AB, with the subsequent simulations carried out using Ansys CFX.