The highly competitive gas turbine industry has been motivated by consumer demands for higher power-to-weight ratios, increased thermal efficiencies, and reliability while maintaining affordability. In its continual quest, the industry must continually try to raise the turbine inlet temperature, which according to the well-known Brayton cycle is key to higher engine efficiencies. The desire for increased turbine inlet temperatures creates an extremely harsh environment for the combustor liner in addition to the components downstream of the combustor. Shear layers between the dilution jets and the mainstream, as well as combustor liner film-cooling interactions create a complex mean flow field within the combustor, which is not easy to model. A completely uniform temperature and velocity profile at the combustor exit is desirable from the standpoint of reducing the secondary flows in the turbine. However, this seldom occurs due to a lack of thorough mixing within the combustor. Poor mixing results in non-uniformities, such as hot streaks, and allow non-combusted fuel to exit the combustor. This investigation developed a database documenting the thermal and flow characteristics within a combustor simulator representative of the flowfield within a gas turbine aero-engine. Three- and two-component laser Doppler velocimeter measurements were completed to quantify the flow and turbulence fields, while a thermocouple rake was used to quantify the thermal fields. The measured results show very high turbulence levels due to the dilution flow injection. Directly downstream of the dilution jets, an increased thickness in the film-cooling was noted with a fairly non-homogeneous temperature field across the combustor width. A highly turbulent shear layer was found at the leading edge of the dilution jets. Measurements also showed that a relatively extensive recirculation region existed downstream of the dilution jets. Despite the lack of film-cooling injection at the trailing edge of the dilution hole, there existed coolant flow indicative of a horse-shoe vortex wrapping around the jet. As a result of the dilution jet interaction with the mainstream flow, kidney-shaped thermal fields and counter-rotating vortices developed. These vortices serve to enhance combustor mixing. / Master of Science

This study focused on experimentally measuring the performance of a fully cooled, scaled up C3X turbine vane. Experimental measurements focused on investigating row-to-row interactions of coolant jets and the contributions of external film cooling and internal impingement cooling to overall cooling effectiveness. Overall effectiveness was experimentally measured using a thermally scaled, matched Biot number vane model featuring a realistic internal impingement scheme and had normalized surface temperatures that were representative of those found on engine components. A geometrically identical vane was also constructed out of low conductivity polystyrene foam to measure the normalized adiabatic wall temperature, or adiabatic effectiveness of the film cooling configuration. The vanes featured a full coverage film-cooling scheme with a five-row showerhead and 13 total rows of holes containing 149 total coolant holes. This study was the first study to make highly detailed measurements of overall effectiveness on a fully-cooled vane model and expands on previous studies of adiabatic and overall effectiveness on the showerhead and single rows of holes on a matched Biot vane by considering a fully cooled configuration to determine if the results from these previous studies also hold for a fully cooled configuration. Additionally, velocity and thermal fields were measured just upstream of two different suction side rows of holes in order to study the effect of introducing upstream coolant injection. The effects of mainstream turbulence and span-wise location were examined and at the downstream row of holes, the contributions of different rows of holes to the approach flow were compared. This study was the first to measure mean and fluctuating velocity data on the suction side of a turbine vane with upstream coolant injection. Understanding the effects of how upstream injection affects the performance of downstream rows of holes is critical to understanding the film cooling performance on a fully cooled turbine airfoil. / text

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-17T18:35:17Z No. of bitstreams: 1 JOÃO GUSTAVO DA SILVA SANTOS Ó – DISSERTAÇÃO (PPGFísica) 2016.pdf: 3276092 bytes, checksum: f4b6dd7217e33af856588a93c1291306 (MD5) / Made available in DSpace on 2018-10-17T18:35:17Z (GMT). No. of bitstreams: 1 JOÃO GUSTAVO DA SILVA SANTOS Ó – DISSERTAÇÃO (PPGFísica) 2016.pdf: 3276092 bytes, checksum: f4b6dd7217e33af856588a93c1291306 (MD5) Previous issue date: 2016-07 / Capes / Desenvolvemos neste trabalho um estudo teórico da aplicação da dinâmica de campo térmico sobre o modelo de Jaynes-Cummings. De acordo com a abordagem feita por Hashizume no artigo, A new perspective to formulate a dissipative ther mo eld dynamics aplicamos os mesmos conceitos para investigar o processo de relaxação envolvido no modelo de Jaynes-Cummings. Num primeiro momento, fi zemos uma revisão de alguns elementos primordiais para a compreensão de toda a discussão envolvida nessa dissertação. Em seguida, estudamos processos de relaxação em sistemas quânticos simples, para podermos, mais tarde, traçar um paralelo entre os resultados e estabelecer alguma relação com o que foi encontrado. Diante da dinâmica de campo térmico, mas conhecida como TFD (ThermoFieldDynamics), usamos uma abordagem feita por Hashiz um e colaboradores, e investigamos como o processo de relaxação se desenvolve mediante a representação via TFD. / We develop in this work, a the or etical study of the application of theThermo eld dynamics on the model of Jaynes-Cummings. According to the approach taken by Hashizu me in the article, A new perspective to formulate a dissipative thermo eld dynamics", we use the same concepts to investigate the relaxation process involved in model Jaynes-Cummings. In the rst moment, we did are view of some key elements to comprenção all the discussion involved in this dissertation. Then, we study relaxation processes in simple quantum systems, for we could later draw a parallel between the results and establish some relationship to what was found. Front the thermal eld dynamics, butknownas TFD, we use an approach made by Hashizu me and colaborators, and we investigated how the relaxation process it developed through there presentation via TFD.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-08-18T12:28:54Z No. of bitstreams: 1 francieledeoliveirapimentel.pdf: 21371696 bytes, checksum: 9023a65af1ac898680a97f2fd00f4bc2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-24T12:01:11Z (GMT) No. of bitstreams: 1 francieledeoliveirapimentel.pdf: 21371696 bytes, checksum: 9023a65af1ac898680a97f2fd00f4bc2 (MD5) / Made available in DSpace on 2017-08-24T12:01:11Z (GMT). No. of bitstreams: 1 francieledeoliveirapimentel.pdf: 21371696 bytes, checksum: 9023a65af1ac898680a97f2fd00f4bc2 (MD5) Previous issue date: 2017-04-07 / A preocupação com os chamados impactos ambientais urbanos fomentou um maior interesse nas pesquisas, principalmente aquelas voltadas para as análises climáticas, na escala urbana. A cidade por consequência de seu processo de organização e estruturação desenvolveu um clima totalmente particular, o clima urbano, isso é possível através da retirada da vegetação original e a inserção dos chamados equipamentos urbanos, como por exemplo, as vias impermeabilizadas, as construções, a verticalização, além da circulação de pessoas e veículos que irão contribuir para maior aquecimento da atmosfera local. Os materiais presentes no meio urbano vão apresentar diferentes valores de albedo, emissividade, absortividade e irradiação e consequentemente, estes condicionarão diferentes valores de temperatura de superfície e que influenciarão na temperatura do ar. O presente estudo tem por objetivo analisar o comportamento do clima urbano na cidade de Juiz de Fora- MG, onde foram trabalhadas 35 regiões urbanas, localizadas ao longo do curso do Rio Paraibuna. O estudo busca através da aplicação de um modelo geoespacial, interligar variáveis que possuem uma conexão direta com a temperatura de superfície e indireta com a temperatura do ar. Este conjunto de dados permitiu alcançar uma maior compreensão, viabilizou a espacialização e consequentemente uma visualização de como se distribuem as áreas e suas diferentes capacidades de criarem distintos campos térmicos na cidade.Além disso, para fins de validação do modelo, foi feita uma correlação estatística entre o modelo matemático proposto e a temperatura de superfície obtida na faixa do infravermelho termal. O modelo utilizado provou possuir consistência para ser adaptado a fim de ser replicado em diferentes cidades com especificidades térmicas além de ser viável a integração de outras informações e dados. / Concern about so-called urban environmental impacts has fostered greater interest in research, especially those focused on climate analysis, on the urban scale. The city as a result of its process of organization and structuring has developed a totally particular climate, the urban climate, this is possible through the removal of the original vegetation and the insertion of so-called urban equipment, such as waterproofed roads, constructions, verticalization, besides the circulation of people and vehicles that will contribute to greater warming of the local atmosphere. The materials present in the urban environment will present different values of albedo, emissivity, absorptivity and irradiation and consequently, these will condition different values of surface temperature and that will influence the air temperature. The present study aims to analyze the behavior of the urban climate in the city of Juiz de Fora- MG, where 35 urban areas were located along the course of the Paraibuna River. The study searches through the application of a geospatial model, interconnecting variables that have a direct coexistence with the surface temperature and indirect with the air temperature. This dataset allowed to reach a greater understanding, made possible the spatialization and consequently a visualization of how the areas are distributed and their different capacities to create different thermal fields in the city. In addition, for purposes of validation of the model, a statistical correlation was made between the proposed mathematical model and the surface temperature obtained in the thermal infrared range. The model used proved to have consistency to be adapted in order to be replicated in different cities with thermal specificities besides being feasible the integration of other information and data.

The efficiency of natural gas turbines is directly linked to the turbine inlet temperature, or the combustor exit temperature. Further increasing the turbine inlet temperature damages the turbine components and limits their durability. Advances in turbine vane cooling schemes protect the turbine components. This thesis studies the conjugate effects of internal cooling, film cooling and thermal barrier coatings (TBC) on turbine vane metal temperatures. Two-dimensional thermal profiles were experimentally measured downstream of a single row of film cooling holes on both an adiabatic and a matched Biot number model turbine vane. The measurements were taken as a comparison to computational simulations of the same model and flow conditions. To improve computational models of the evolution of a film cooling jet as it propagates downstream, the thermal field above the vane, not just the footprint on the vane surface must be analyzed. This study expands these data to include 2-D thermal fields above the vane at 0, 5 and 10 hole diameters downstream of the film cooling holes. In each case the computational jets remained colder than the experimental jets because they did not disperse into the mainstream as quickly. Finally, in comparing results above adiabatic and matched Biot number models, these thermal field measurements allow for an accurate analysis of whether or not the adiabatic wall temperature was a reasonable estimate of the driving temperature for heat transfer. In some cases the adiabatic wall temperature did give a good indication of the driving temperature for heat transfer while in other cases it did not. Previous tests simulating the effects of TBC on an internally and film cooled model turbine vane showed that the insulating effects of TBC dominate over variations in film cooling geometry and blowing ratio. In this study overall and external effectiveness were measured using a matched Biot number model vane simulating a TBC of thickness 0.6d, where d is the film cooing hole diameter. This new model was a 35% reduction in thermal resistance from previous tests. Overall effectiveness measurements were taken for an internal cooling only configuration, as well as for three rows of showerhead holes with a single row of holes on the pressure side of the vane. This pressure side row of holes was tested both as round holes and as round holes embedded in a realistic trench with a depth of 0.6 hole diameters. Even in the case of this thinner TBC, the insulating effects dominate over film cooling. In addition, using measurements of the convective heat transfer coefficient above the vane surface, and the thermal conductivities of the vane wall and simulated TBC material, a prediction technique of the overall effectiveness with TBC was evaluated. / text

Les travaux présentés dans cette thèse s'inscrivent un contexte d'amélioration de la productivité des pièces en TA6V. La maîtrise de l'usinage de cet alliage constitue un enjeu majeur pour les sous-traitants comme l'entreprise SOFOP qui doivent suivre les montées en cadence des principaux programmes aéronautiques. La première partie, basée sur un état de l'art académique, s'attache à identifier différents critères d'usinabilité du matériau au travers de plusieurs échelles. Dans un second temps, la démarche du Couple Outil-Matière (COM) est mise en œuvre sur deux outils utilisés par l'industriel afin de déterminer un espace de fonctionnement des conditions opératoires garantissant une amélioration de la productivité. La confrontation entre les résultats de la campagne expérimentale du COM et de l'application en contexte industriel a permis de souligner le fort impact de la stratégie d'usinage sur la durée de vie de l'outil de coupe. L'influence sur les mécanismes d'usure de la vitesse de coupe, souvent utilisée comme paramètre d'ajustement de la durée de vie en production, ainsi que de l'engagement radial de l'outil inhérent au parcours a été investiguée au travers d'un dispositif expérimental spécialement équipé d'une caméra thermique. Les liens entre les champs de températures et l'usure de l'outil de coupe ont ensuite été établis par des analyses MEB et EDX. L'étude phénoménologique ne permettant pas de pondérer l'impact des parcours d'usinage sur la durée de vie de l'outil de coupe, une approche statistique a alors été adoptée. Basée sur la récolte de la puissance de coupe en usinage, les corrélations établies entre les caractéristiques des signaux et la durée de vie de l'outil ont abouti à la proposition d'une modélisation expérimentale, fiabilisée vers de deux applications industrielles : une méthode de prédiction en amont de la production et une approche de surveillance de l'étatd'usure de l'outil en usinage / The work presented in this thesis aims at improving productivity when manufacturing TA6V parts. Knowledge and control of the milling process for this titanium alloy are a key challenge particularly for medium size companies like SOFOP who try to answer the increasing aeronautical parts market demand. The first section is focused on machinability criteria which are discussed through several scales. Then, following the couple tool-material method, working zones of two tools are determined in order to achieve productivity improvements. This results, obtained through laboratory tests have been faced with their industrial application and showed the strong links between milling paths and tool life. Influence of cutting speed and radial engagement has been investigated with a specifically developed experimental bench, equipped with a thermal camera. Indeed, the rst parameter is often considered as an adjustment variable for tool life during the validation phase and the other one is deeply linked with tool path. Temperature fields and tool wear have been correlated thanks to SEM and EDX images. Given the fact that the phenomenological study is not able to weight the impact of the tool path on tool life, a statistical approach hase been adopted. Based on cutting power signal collection, correlations have been established between signal features and tool life and led to the proposal of a verified experimental model allowing to consider two industrial applications : a tool life prediction method during the industrialization phase and an online tool life monitoring approach

Ziel der Arbeit war die Entwicklung des Elektronenstrahl-Mehrspot/Mehrprozess-Schweißens für Gusseisen/Gusseisen- und Gusseisen/Stahl-Verbindungen ohne Schweißzusatzstoffe. Im Vergleich zum Einbad-Schweißen entsteht beim Mehrbad-Schweißen eine porenarme Schweißnaht, gleichzeitig senkt sich die Schweißnahthärte geringfügig ab. Dabei kann die Kaltrissbildung in der Schweißnaht für arteigene Gusseisen-Verbindungen nicht unterdrückt werden. Für Mischverbindungen ist der Strahlversatz der bestimmende Schweißparameter beim Mehrbad-Schweißen. Über diesen kann sowohl die chemische Zusammensetzung der Schweißnaht eingestellt als auch ohne Vorwärmen eine kaltrissfreie Schweißnaht für Gusseisen/Stahl-Verbindungen erzeugt werden. Für die prozessintegrierte Wärmebehandlung der Fügezone wurde ein neues EB-Thermofeld entwickelt. Durch den Thermofeldeinsatz konnte die Aufhärtung in der Schmelz- und Wärmeeinflusszone signifikant reduziert werden und die mechanischen Eigenschaften der Schweißverbindungen wurden deutlich verbessert.

Ziel der Arbeit war die Entwicklung des Elektronenstrahl-Mehrspot/Mehrprozess-Schweißens für Gusseisen/Gusseisen- und Gusseisen/Stahl-Verbindungen ohne Schweißzusatzstoffe. Im Vergleich zum Einbad-Schweißen entsteht beim Mehrbad-Schweißen eine porenarme Schweißnaht, gleichzeitig senkt sich die Schweißnahthärte geringfügig ab. Dabei kann die Kaltrissbildung in der Schweißnaht für arteigene Gusseisen-Verbindungen nicht unterdrückt werden. Für Mischverbindungen ist der Strahlversatz der bestimmende Schweißparameter beim Mehrbad-Schweißen. Über diesen kann sowohl die chemische Zusammensetzung der Schweißnaht eingestellt als auch ohne Vorwärmen eine kaltrissfreie Schweißnaht für Gusseisen/Stahl-Verbindungen erzeugt werden. Für die prozessintegrierte Wärmebehandlung der Fügezone wurde ein neues EB-Thermofeld entwickelt. Durch den Thermofeldeinsatz konnte die Aufhärtung in der Schmelz- und Wärmeeinflusszone signifikant reduziert werden und die mechanischen Eigenschaften der Schweißverbindungen wurden deutlich verbessert.