Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-11Bitstream added on 2014-06-13T20:58:35Z : No. of bitstreams: 1 mazur_rl_me_guara.pdf: 2192483 bytes, checksum: 24772053abc0675fdf4455448fe4adc3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / As superligas à base de níquel são aplicadas nos mais diversos e complexos sistemas de engenharia, entretanto há poucos dados sobre o comportamento erosivo destas superligas frente ao impacto de particulas sólidas em um fluxo gasoso. A erosão por partícula sólida é um fenômeno complexo e caracteriza-se pela deformação e remoção de material durante o impacto das partículas, gerando elevadas temperaturas. As superligas à base de níquel Nimonic 80 A e Inconel 600, são materiais que possuem ótimas propriedades mecânicas emelevadas temperaturas, por este motivo, as suas características quanto à erosão em temperatura ambiente, serão medidas e analisadas, em vista da perda das propriedades mecânicas dos aços em temperaturas mais altas durante o impacto das partículas. Os ensaios de erosão foram realizados em um dispositivo do tipo jato de impacto ar-areia, onde as partículas erosivas forma introduzidas em um sistema à alta pressão e aceleradas ao longo de um bocal antes de impactar a superfície do material, permitindo simular os principais parâmetros do desgaste erosivo. Os ensaios realizados apresentaram pequenas diferenças para todosângulos de impacto testados (15°, 30°, 60°, 90°), porém os intervalos de confiança se superpõem para quase todos eles apesar da marcante diferença entre as propriedades mecânicas das superligas Nimonic 80 A e Inconel 600, não sendo possível estabelecer alguma correlação com a resistência à erosâo. / The Ni-base superalloys are applied in several and complexest engineering systems, however there are few data about the erosive behaviour of these superalloys regarding the impact of solid particles in a gaseous flow. The solid particle erosion is a complex phenomenon and it is characerized by the deformation and material removal during the impact of the particles generating high temperatures. The Ni-basesuperalloys Nimonic 80 A and Inconel 600, have excellent mechanical properties in high temperature, by this reason, theirs characteristics in erosion at room temperature, will be measured and analyzed, in view of the losses of the mechanical properties of the steels in higher temperatures during the impact of the particles. The erosion tests have been performed in air-sand jet impingement device, where the erosive particles were introduced in a system with high pressure and accelerated along a nozzle before impact the surface of the material, allowing to simulate the main parameters of the erosion wear. The results showed small differences for all impact angles tested (15°, 30°, 60°, 90°), however the reliable intervals have been superimpsed for almost all of them, in spite of the great differences among the mechanical properties of the superalloys Nimonic 80 A and Inconel 600, it was noto possible to establish some correlation with the erosion resistance.

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Orientador: Sérgio João Crnkovic / Resumo: As superligas à base de níquel são aplicadas nos mais diversos e complexos sistemas de engenharia, entretanto há poucos dados sobre o comportamento erosivo destas superligas frente ao impacto de particulas sólidas em um fluxo gasoso. A erosão por partícula sólida é um fenômeno complexo e caracteriza-se pela deformação e remoção de material durante o impacto das partículas, gerando elevadas temperaturas. As superligas à base de níquel "Nimonic 80 A" e Inconel 600", são materiais que possuem ótimas propriedades mecânicas emelevadas temperaturas, por este motivo, as suas características quanto à erosão em temperatura ambiente, serão medidas e analisadas, em vista da perda das propriedades mecânicas dos aços em temperaturas mais altas durante o impacto das partículas. Os ensaios de erosão foram realizados em um dispositivo do tipo jato de impacto ar-areia, onde as partículas erosivas forma introduzidas em um sistema à alta pressão e aceleradas ao longo de um bocal antes de impactar a superfície do material, permitindo simular os principais parâmetros do desgaste erosivo. Os ensaios realizados apresentaram pequenas diferenças para todosângulos de impacto testados (15°, 30°, 60°, 90°), porém os intervalos de confiança se superpõem para quase todos eles apesar da marcante diferença entre as propriedades mecânicas das superligas "Nimonic 80 A" e Inconel 600", não sendo possível estabelecer alguma correlação com a resistência à erosâo. / Abstract: The Ni-base superalloys are applied in several and complexest engineering systems, however there are few data about the erosive behaviour of these superalloys regarding the impact of solid particles in a gaseous flow. The solid particle erosion is a complex phenomenon and it is characerized by the deformation and material removal during the impact of the particles generating high temperatures. The Ni-basesuperalloys "Nimonic 80 A" and Inconel 600", have excellent mechanical properties in high temperature, by this reason, theirs characteristics in erosion at room temperature, will be measured and analyzed, in view of the losses of the mechanical properties of the steels in higher temperatures during the impact of the particles. The erosion tests have been performed in air-sand jet impingement device, where the erosive particles were introduced in a system with high pressure and accelerated along a nozzle before impact the surface of the material, allowing to simulate the main parameters of the erosion wear. The results showed small differences for all impact angles tested (15°, 30°, 60°, 90°), however the reliable intervals have been superimpsed for almost all of them, in spite of the great differences among the mechanical properties of the superalloys "Nimonic 80 A" and "Inconel 600", it was noto possible to establish some correlation with the erosion resistance. / Mestre

Centrifugal separation is a crucial piece of technology, used in a wide range of industries. In cases where solid particles are included in the working medium, erosive wear of componentsinside a centrifugal separator is one of the reasons limiting its service life. In the present work, erosion of some candidate materials of metals, hard metals and polymers were tested to represent the erosive conditions inside a centrifugal separator, and to study the erosion behavior between different material groups. A literature study was conducted to give an overview of the field of erosion, and to evaluate which erosion parameters to consider for testing. A centrifugal erosion test rig was used for the testing, using natural sand, sieved to a size interval of 500 to 700 µm, as erodent, at both 90° and 30° impact angle. Every material was tested at 100 m/s impact velocity, while only metals and polymers were tested at 70 m/s. The erosion rates, volumes of material removed per mass of impinging erodent, were measured and used to rank the candidate materials within each respective material group. Surface analysis of the eroded surfaces were conducted, using SEM, to determine the mechanism of material removal. Relation between erosion resistance, erosion mechanism and material property were investigated.

Transportation of unprocessed multiphase reservoir fluids from deep/ultra deep offshore through a long subsea tieback/pipeline is inevitable. This form of transportation is complex and requires accurate knowledge of critical transport velocity, flow pattern changes, phase velocity, pressure drop, particle drag & lift forces, sand/liquid/gas holdup, flow rate requirement and tieback sizing etc at the early design phase and during operation for process optimisation. This research investigated sand transport characteristics in multiphase, water‐oil‐gas‐sand flows in horizontal, inclined and vertical pipes. Two critical factors that influence the solid particle transport in the case of multiphase flow in pipes were identified; these are the transient phenomena of flow patterns and the characteristic drag & lift coefficients ( D C , L C ). Therefore, the equations for velocity profile were developed for key flow patterns such as dispersed bubble flow, stratified flow, slug flow and annular flow using a combination of analytical equations and numerical simulation tool (CFD). The existing correlations for D C & L C were modified with data acquired from multiphase experiment in order to account for different flow patterns. Minimum Transport Velocity (MTV) models for suspension and rolling were developed by combining the numerically developed particle velocity profile models with semi‐empirical models for solid particle transport. The models took into account the critical parameters that influence particle transport in pipe flow such as flow patterns and particle drag & lift coefficients, thus eliminate inaccuracies currently experienced with similar models in public domain. The predictions of the proposed MTV models for suspension and rolling in dispersed bubble, slug flow and annular flow show maximum average error margin of 12% when compared with experimental data. The improved models were validated using previously reported experimental data and were shown to have better predictions when compared with existing models in public domain. These models have the potential to solve the problems of pipe and equipment sizing, the risk of sand deposition and bed formation, elimination of costs of sand unloading, downtime and generally improve sand management strategies.

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Magistriniame darbe tirtas turbulentinis dvifazis srautas C- 30 ir KDG ciklonuose (įrenginys KD atskirti iš oro srauto) su tangentiniu srauto įtekėjimu problema. Pagrindinis tyrimo objektas – dviejų skirtingų konstrukcijų ciklonų oro valymo įrenginiai nuo KD. Magistrinio darbo tikslas yra ištirti turbulentinio dvifazio srauto judėjimą C-30 ir KDG ciklonuose ir atlikti matematinį modeliavimą. Magistrinį darbą sudaro 106 puslapiai, 3 skyriai, 21 lentelių, 58 paveikslai, bendrosios darbo išvados ir rekomendacijos, literatūros sąrašas. Pirmajame skyriuje analizuota literatūra, išnagrinėta oro tarša KD, pasaulyje ir Lietuvoje naudojamų ciklonų konstrukcijos. Aprašyti KD judėjimo ciklone matematiniai modeliai. Antrajame skyriuje pateiktos tyrimo metodikos: eksperimentiniuose tyrimuose naudotų medžiagų, įrangos bei aparatūros charakteristikos, pateikiamos mėginių ėmimo sąlygos, taikomi KD koncentracijų analizavimo metodai (svorinis ir spektroskopinis) bei skaitinio modeliavimo („Gentra“ ir „IPSA“) metodikos. Trečiajame skyriuje pateikti eksperimentinių tyrimų ir matematinio modeliavimo rezultatai. Eksperimentiniais tyrimais buvo siekiama ištirti C-30 ir KDG ciklonų efektyvumus, nustatyti medienos skiedrų, kūrenamomis kūrykloje išsiskiriančių kietųjų dalelių koncentracijas, kvarcinio smėlio ir kvarcinio smėlio dulkių įeinančio ir išeinančio oro dulkių sraute. Atliktas skaitinis oro srauto judėjimo modeliavimas. Oro srauto judėjimui C-30 ir KDG ciklonuose aprašyti naudotas trimačių... [toliau žr. visą tekstą] / The paper aims to analyse the problem og numerical modeling of two-phase flow in the C- 30 ir CRF cyclone with tangential inlet (equipment for seperation of solid particles from gaseous fluid flow). The main research object is two different structures of cyclone air cleaning equipment used to remove solid particles. The master is aimed to investigate the turbulent two-phase flow in the C-30 and CRF cyclones and describes the numerical modeling The master work consists of an 106 papers, 3 chapters, 21 tables, 58 pictures, general conclusions and recommendations, lists of references. The first chapter is intended for literature review. It investigates air pollution with solid particles, cyclones structures and charges applied worldwide and Lithuania. It also describes the mathematical models of a solid particle flow in cyclone. The second chapter presents the methodologies of research: experimental research of the materials, characteristics of equipment and hardware, present the sampling conditions, used analysis methods of solid particle concentrations (weighted and spectroscopic) and method of numerical modeling (Gentra and IPSA). The third chapter presents results of experimental research and mathematical modeling. In experimental analysis was to investigate efficiency of air cleaning equipment C-30 and CRF cyclones and assess the wood chips, combustion emissions from burning the particles concentrations of quartz sand and quartz sand dust of incoming and outgoing air... [to full text]

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Thermal Barrier Coating systems (TBCs) serve as a key component in gas turbines in aerospace engines, isolating the metallic substrate from severe heat flux of the environment. The durability of TBCs has been considered to be a critical issue to determine the service lifespan of hot section components. Comprehensive studies of failure mechanisms benefit the gas turbine industry to develop TBCs with better material properties and stable microstructures, thus potentially enhancing their durability. To date, many failure mechanism analyses have been conducted based on the understanding of critical residual stress developed under different thermal tests. For the present study, using the Finite Element (FE) method with temperature-process-dependent model parameters, the maximum residual stress is calculated with evolution of the localized/global interfacial roughness profile based on Electron Beam-Physical Vapour Deposition Thermal Barrier Coating system (EB-PVD TBCs). With studies of cracking routes from past research, qualitative failure mechanism analysis is conducted for EB-PVD TBCs. In addition, the estimated energy release rates are compared to reveal the effect of different thermal profiles on the crack driving forces for Atmospheric Plasma Sprayed Thermal Barrier Coating systems (APS-TBCs). Using previously observed cracking routes from different thermal cycling experiments, a quantitative failure mechanism analysis is conducted for APS-TBCs with modified analytical expressions. In addition, literature works revealed that physics and mechanics-based models were proposed to evaluate environment induced damage. For the last part of my research, erosion of EB-PVD TBCs is estimated using a modified solid particle erosion model. A stochastic approach is applied to study the erosion of EB-PVD topcoat (TC) under real engine service conditions. The durability of TBCs is affected by both oxidation-induced degradation and environment-induced damage. The combination of “internal” crack driving forces (generated from residual stresses developed upon different stages of thermal cycles) and “external” erosion damage (from temperature-process dependent brittle/ductile erosion) lead to complexity of evaluating durability under different service conditions.