Dissertations / Theses on the topic 'Turbine, CFD, LES, Combustor-turbine interaction'
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Legrenzi, Paolo. "A coupled CFD approach for combustor-turbine interaction." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/26436.
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The current approach in the industry to numerically investigate the flow in a gas turbine considers each component, such as combustor and turbine, as a stand-alone part, involving no or very minor interactions with other parts, mainly applied through static boundary conditions. Efficient and very specialised CFD codes have been developed in the past to address the different flow characteristic occurring in the different regions of the engine. In order to meet the future requirements in terms of fuel consumption and pollutants emissions, an integrated approach capable of capturing all the possible interactions between different components is necessary. An efficient and accurate way to achieve integrated simulations is to couple already existing specialised codes in a zonal type of coupling. In this Thesis work a methodology to couple an incompressible/low-Mach number pressure-based combustion code with a compressible density-based turbomachinery code for industrial application has been developed. In particular two different couplings have been implemented: the first, based on the exchange of existing boundary conditions through files, comes as a completely separated tools from the original codes, of which no modifications are required, and it is applied to steady state simulations; the second instead, based on the exchange of boundary conditions and body forces through message passing, requires some modifications of the source codes and it is applied to both steady and unsteady cases. A simple analysis shows that not all the primitive variables can be made continuous at the coupling interface between the two codes and a compromise was found that allows minor discontinuity in some of the variables while achieving mass flow conservation and continuity of the temperature profiles. The coupling methodology has been applied to a simplified but realistic industrial case, consisting of a RQL (Rich Burn - Quick quench - Lean burn) combustor coupled with the first stage of the HP turbine. The analysis of the steady case has shown that the combustor field is affected as far as 150% axial chord lengths upstream of the blades leading edge, affecting RTDF and OTDF at the interfaces. In the turbine stage significant differences in both efficiency and degree of reaction were found in the coupled cases with respect to standard standalone simulations using radial inlet profiles. The analysis of the unsteady simulation has instead shown the hot streaks behaviour across the turbine, that are only partially mitigated by the stator blades and, due to segregation effect of hot and cold gases, migrate towards the pressure side of the rotor blades.
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Stitzel, Sarah M. "Flow Field Computations of Combustor-Turbine Interactions in a Gas Turbine Engine." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/30992.
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The current demands for higher performance in gas turbine engines can be reached by raising combustion temperatures to increase thermal efficiency. Hot combustion temperatures create a harsh environment which leads to the consideration of the durability of the combustor and turbine sections. Improvements in durability can be achieved through understanding the interactions between the combustor and turbine. The flow field at a combustor exit shows non-uniformities in pressure, temperature, and velocity in the pitch and radial directions. This inlet profile to the turbine can have a considerable effect on the development of the secondary flows through the vane passage.
This thesis presents a computational study of the flow field generated in a non-reacting gas turbine combustor and how that flow field convects through the downstream stator vane. Specifically, the effect that the combustor flow field had on the secondary flow pattern in the turbine was studied. Data from a modern gas turbine engine manufacturer was used to design a realistic, low speed, large scale combustor test section. This thesis presents the results of computational simulations done in parallel with experimental simulations of the combustor flow field.
In comparisons of computational predictions with experimental data, reasonable agreement of the mean flow and general trends were found for the case without dilution jets. The computational predictions of the combustor flow with dilution jets indicated that the turbulence models under-predicted jet mixing. The combustor exit profiles showed non-uniformities both radially and circumferentially, which were strongly dependent on dilution and cooling slot injection. The development of the secondary flow field in the turbine was highly dependent on the incoming total pressure profile. For a case with a uniform inlet pressure in the near-wall region no leading edge vortex was formed. The endwall heat transfer was found to also depend strongly on the secondary flow field, and therefore on the incoming pressure profile from the combustor.Master of Science
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Jöcker, Markus. "Numerical Investigation of the Aerodynamic Vibration Excitation of High-Pressure Turbine Rotors." Doctoral thesis, KTH, Energy Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3416.
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The design parameters axial gap and stator count of highpressure turbine stages are evaluated numerically towards theirinfluence on the unsteady aerodynamic excitation of rotorblades. Of particular interest is if and how unsteadyaerodynamic considerations in the design could reduce the riskofhigh cycle fatigue (HCF) failures of the turbine rotor.
A well-documented 2D/Q3D non-linear unsteady code (UNSFLO)is chosen to perform the stage flow analyses. The evaluatedresults are interpreted as aerodynamic excitation mechanisms onstream sheets neglecting 3D effects. Mesh studies andvalidations against measurements and 3D computations provideconfidence in the unsteady results. Three test cases areanalysed. First, a typical aero-engine high pressure turbinestage is studied at subsonic and transonic flow conditions,with four axial gaps (37% - 52% of cax,rotor) and two statorconfigurations (43 and 70 NGV). Operating conditions areaccording to the resonant conditions of the blades used inaccompanied experiments. Second, a subsonic high pressureturbine intended to drive the turbopump of a rocket engine isinvestigated. Four axial gap variations (10% - 29% ofcax,rotor) and three stator geometry variations are analysed toextend and generalise the findings made on the first study.Third, a transonic low pressure turbine rotor, known as theInternational Standard Configuration 11, has been modelled tocompute the unsteady flow due to blade vibration and comparedto available experimental data.
Excitation mechanisms due to shock, potential waves andwakes are described and related to the work found in the openliterature. The strength of shock excitation leads to increasedpressure excitation levels by a factor 2 to 3 compared tosubsonic cases. Potential excitations are of a typical wavetype in all cases, differences in the propagation direction ofthe waves and the wave reflection pattern in the rotor passagelead to modifications in the time and space resolved unsteadypressures on the blade surface. The significant influence ofoperating conditions, axial gap and stator size on the wavepropagation is discussed on chosen cases. The wake influence onthe rotorblade unsteady pressure is small in the presentevaluations, which is explicitly demonstrated on the turbopumpturbine by a parametric study of wake and potentialexcitations. A reduction in stator size (towards R≈1)reduces the potential excitation part so that wake andpotential excitation approach in their magnitude.
Potentials to reduce the risk of HCF excitation in transonicflow are the decrease of stator exit Mach number and themodification of temporal relations between shock and potentialexcitation events. A similar temporal tuning of wake excitationto shock excitation appears not efficient because of the smallwake excitation contribution. The increase of axial gap doesnot necessarily decrease the shock excitation strength neitherdoes the decrease of vane size because the shock excitation mayremain strong even behind a smaller stator. The evaluation ofthe aerodynamic excitation towards a HCF risk reduction shouldonly be done with regard to the excited mode shape, asdemonstrated with parametric studies of the mode shapeinfluence on excitability.
Keywords:Aeroelasticity, Aerodynamics, Stator-RotorInteraction, Excitation Mechanism, Unsteady Flow Computation,Forced Response, High Cycle Fatigue, Turbomachinery,Gas-Turbine, High-Pressure Turbine, Turbopump, CFD, Design
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Koupper, Charlie. "Unsteady multi-component simulations dedicated to the impact of the combustion chamber on the turbine of aeronautical gas turbines." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14187/1/koupper_partie_1_sur_2.pdf.
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De nos jours, seules les turbines à gaz sont à même de propulser les larges aéronefs (avions ou hélicoptères). Depuis les premiers prototypes construits dans les années 40, l’efficacité et la puissance de ces moteurs n’ont cessé de s’améliorer. Chaque composant atteint de tels niveaux de performance que seules une rupture technologique ou un investissement conséquent peuvent permettre de repousser les limites d’efficacité d’une turbine à gaz. Une solution alternative peut être trouvée en constatant qu’un moteur est un système intégré complexe dans lequel tous les composants interagissent entre eux, affectant les performances de chaque module en comparaison de leur fonctionnement isolé. Avec la compacité croissante des turbines à gaz, ces interactions entre modules du moteur sont clairement renforcées et leur étude constitue une potentielle source de gain en termes de performance globale du moteur. Dans ce contexte, l’interface du moteur la plus critique est aujourd’hui la connexion entre la chambre de combustion et la turbine, qui présente les niveaux de pression, température et contraintes les plus élevés du moteur. L’objectif de cette thèse est d’améliorer la caractérisation actuelle de l’interface chambre- turbine afin de juger les méthodes de développement de cette interface et de concourir à l’amélioration des performances de la turbine et sa durée de vie. Pour ainsi faire, un nouveau simulateur de chambre non réactif, représentatif des architectures de chambres pauvres récentes, est développé dans le contexte du projet européen FACTOR (FP7). L’écoulement dans le module est analysé d’une part via le recours massif aux Simulations aux Grandes Echelles (LES), et d’autre part par une caractérisation expérimentale sur une version trisecteur du module, installée à l’Université de Florence (Italie). En tirant profit des complémentarités entre approche numérique et expérimentale, une base de données exhaustive est construite pour qualifier les simulations avancées et caractériser les quantités physiques à l’interface entre la chambre et la turbine. Des diagnostics avancés et des procédures de validation s’appuyant sur les riches données temporelles sont proposés dans l’objectif d’améliorer les processus de design de l’interface chambre-turbine. Par exemple, il est montré qu’il est parfois possible et nécessaire d’aller au-delà d’une simple analyse des moyennes et variances pour qualifier les prédictions à cette interface. Pour approfondir l’étude de l’interaction chambre-turbine, des simulations LES comprenant à la fois le simulateur de chambre et une paire de stators de la turbine haute pression sont réalisées. Ces prédictions purement numériques mettent en évidence l’effet potentiel induit par la présence des stators ainsi que l’influence du calage angulaire par rapport aux injecteurs. Ce dernier ensemble de simulations souligne la difficulté de proprement appréhender l’interface chambre-turbine, mais confirme qu’il peut être simulé par une approche LES à l’avenir.
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Feilhauer, Michal. "Řešení dynamické odezvy vodohospodářských konstrukcí v interakci s kapalinou." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-355595.
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Behaviour prediction of hydraulic steel structures with the view to surrounding influences in various design dispositions is a fundamental condition for operational reliability assessment of the analyzed construction. Reliable characteristics of construction behaviour defined by the specification of its movement within changes caused by time and environmental influences is of great importance. In currently used engineering mechanics formulation it concerns setting the response of the defined construction or its part to the given time variable mechanic load. Required response values, which are necessary for evaluation terminal dispositions of capacity and usability of the construction, are trans-location and tension, or values thence derived. Calculation is basic means for response prediction of construction. The thesis presented deals with complex multi-physical behaviour problems of water supply constructions in fluid structure interaction. There are presented various approaches to calculations of static and dynamic qualities of constructions. These approaches are divided into so called “direct method”, which is based on direct connection between two physical fields and the calculation is performed by the method of final elements, and so called “indirect method” , which is based on connection of two physical fields by means of various interfaces, which are described in this thesis. In case of indirect method, the calculation of running liquid is performed by the method of final volumes and the construction calculation is performed by the method of final elements. Within the scope of this thesis, static and dynamic responses of water supply constructions have been solved with the use of the above mentioned approaches. The results of the calculations in the scope of this thesis have been compared with the findings of performed experiments. The final part of the thesis describes the results and generalized findings gathered from the tasks by various approaches.
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Papadogiannis, Dimitrios. "Coupled Large Eddy Simulations of combustion chamber-turbine interactions." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14169/1/Papadogiannis_partie_1_sur_3.pdf.
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Modern gas turbines are characterized by compact designs that enhance the interactions between its different components. Combustion chamber-turbine interactions, in particular, are critical as they may alter the aerothermal flow field of the turbine which can drastically impact the engine life duration. Current state-of-the-art treats these two components in a decoupled way and does not take into account their interactions. This dissertation proposes a coupled approach based on the high-fidelity Large Eddy Simulation (LES) formalism that can take into account all the potential paths of interactions between components. In the first part of this work, an overset grid method is proposed to treat rotor/stator configurations in a rigorous fashion that is compatible with the LES solver AVBP. This interface treatment is shown not to impact the characteristics of the numerical schemes on a series of academic test cases of varying complexity. The approach is then validated on a realistic high-pressure turbine stage. The results are compared against experimental measurements and the influence of different modeling and simulation parameters is evaluated. The second part of this work is dedicated to the prediction of combustion chamber-turbine interactions using the developed methodologies. The first type of interactions evaluated is the indirect combustion noise generation across a high-pressure turbine stage. This noise arises when combustor-generated temperature heterogeneities are accelerated in the turbine. To simplify the simulations the heterogeneities are modeled by sinusoidal temperature fluctuations injected in the turbine through the boundary conditions. The noise generation mechanisms are revealed by such LES and the indirect combustion noise is measured and compared to an analytical theory and 2D predictions. The second application is a fully-coupled combustor-turbine simulation that investigates the interactions between the two components from an aerothermal point of view. The rich flow characteristics at the turbine inlet, issued by the unsteady combustion in the chamber, are analyzed along with the migration of the temperature heterogeneities. A standalone turbine simulation serves as a benchmark to compare the impact of the fully coupled approach.
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Johnson, Benjamin Michael Carver. "Computational Fluid Dynamics (CFD) modelling of renewable energy turbine wake interactions." Thesis, University of Central Lancashire, 2015. http://clok.uclan.ac.uk/12120/.
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This thesis presents Computational Fluid Dynamics (CFD) simulations of renewable turbines akin to those used for wind, hydro, and tidal applications. The models developed took the form of actuator discs with the solution of incompressible Reynolds-Averaged Navier-Stokes equations with the k-ω SST turbulence models. Simulations were initially conducted of a single turbine in water and air and then two axially aligned turbines to study the flow field interactions. These models were compared with previous theoretical, experimental and numerical data evident in the literature. Generally, good agreement was found between these models and other analogous data sources in terms of velocity profiles in the far wake. The actuator disc method was underpinned using the transient actuator line method, which showed good agreement from a quantitative and qualitative viewpoint. However, it required significant additional computational time when compared to the actuator disc method. Each of the models were developed and solved using complimentary commercially available CFD codes, ANSYS-CFX and ANSYS-Fluent. For this type of study, a critical evaluation of these codes was in all probability performed for the first time, where it is shown that for the studies investigated in this thesis ANSYS-CFX performed better than ANSYS-Fluent with respect to the computational effort (i.e. time and lines of code).
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De, Carvalho Duarte Leandro. "Conception et optimisation d'un système hydrolien à aile oscillante passive." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD038.
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Dans un scénario de transition énergétique où la production et les grands réseaux de distribution d’électricité sont remis en cause, le potentiel de production au niveau des écoulements à faible vitesse est important et reste encore peu exploité. Cette thèse étudie un concept novateur d’hydrolienne permettant de répondre en partie à cette problématique : le système hydrolien à aile oscillante passive. Bioinspiré de la nage d’animaux aquatiques, ce dispositif de récupération de l’énergie cinétique des courants consiste en une aile décrivant des mouvements périodiques de pilonnement et de tangage, entièrement induits par les interactions fluide-structure. Une première partie du travail a porté sur la construction d’un modèle numérique permettant de reproduire fidèlement le comportement du système. Un prototype d’aile oscillante passive à échelle réduite a ensuite été conçu et testé dans un canal hydraulique. Grâce à une technique de réglage dynamique des paramètres structuraux, le système a pu être étudié expérimentalement sur une large gamme de paramètres mécaniques et hydrauliques. L’étude des performances énergétiques du prototype a permis d’identifier des conditions de fonctionnement optimales. Dans ces conditions, des rendements hydrauliques supérieurs à 30% ont été obtenus. Les résultats de ce travail de thèse permettent d’envisager maintenant l’installation d’un système hydrolien à aile oscillante passive en milieu naturel. En effet, les configurations optimales identifiées à l’échelle réduite peuvent s’étendre naturellement à des conditions hydrauliques réellesGiven the current energy transition conjuncture, where the electricity production and the electricity grid are challenged, the hydraulic potential of low current sites is relevant and remains under-exploited. In such context, this thesis studies a novel concept of an energy harvester device: the fully passive flapping foil turbine. Bioinspired from aquatic animals swimming technique, this hydrokinetic energy harvester consists of an oscillating foil describing periodic heaving and pitching motions, entirely induced by fluid-structure interactions. The first part of this thesis deals with the development of a numerical model for accurately simulating the harvester behavior. Then, a reduced scale prototype of the fully passive flapping foil has been designed and tested in a water channel. Thanks to an original dynamic tuning strategy of the structural parameters, experiments have been conducted for a wide range of configurations of the harvester. The investigation of the harvesting performances of the prototype helped identifying several optimized parameters sets. In such cases, hydraulic efficiencies as high as 30% have been reached. The main results of this thesis allow to consider a full scale fully passive flapping foil harvester in realistic conditions. As a matter of fact, the optimized cases identified for the reduced scale prototype can be naturally extended to real operating conditions
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Eriksson, Ola. "Numerical Computations of Wakes Behind Wind Farms." Licentiate thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255859.
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More and larger wind farms are planned offshore. As the most suitable build sites are limited wind farms will be constructed near to each other in so called wind farm clusters. Behind the wind turbines in these farms there is a disrupted flow of air called a wake that is characterized by reduced wind speed and increased turbulence. These individual turbine wakes combine to form a farm wake that can travel a long distance. In wind farm clusters farm to farm interaction will occur, i.e. the long distance wake from one wind farm will impact the wind conditions for other farms in the surrounding area. The thesis contains numerical studies of these long distance wakes. In this study Large Eddy Simulations (LES) using an Actuator Disc method (ACD) are used. A prescribed boundary layer is used where the wind shear is introduced using body forces. The turbulence, based on the Mann model, is introduced as fluctuating body forces upstream of the farm. A neutral atmosphere is assumed. The applied method has earlier been used for studies of wake effects inside farms but not for the longer distances needed for farm to farm interaction. Numerical studies are performed to get better knowledge about the use of this model for long distance wakes. The first study compares the simulation results with measurements behind an existing farm. Three parameter studies are thereafter setup to analyze how to best use the model. The first parameter study examines numerical and physical parameters in the model. The second one looks at the extension of the domain and turbulence as well as the characteristics of the flow far downstream. The third one gathers information on the downstream development of turbulence with different combinations of wind shear and turbulence level. The impact of placing the turbines at different distances from the turbulence plane is also studied. Finally a second study of an existing wind farm is performed and compared with a mesoscale model. The model is shown to be relevant also for studies of long distance wakes. Combining LES with a mesoscale model can be of interest.
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Klapdor, Eva Verena [Verfasser], Johannes [Akademischer Betreuer] Janicka, and Heinz-Peter [Akademischer Betreuer] Schiffer. "Simulation of Combustor-Turbine Interaction in a Jet Engine / Eva Verena Klapdor. Betreuer: Johannes Janicka ; Heinz-Peter Schiffer." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2011. http://d-nb.info/1105562603/34.
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Blunt, Rory Alexander Fabian. "A Study of the Effects of Turning Angle on Particle Deposition in Gas Turbine Combustor Liner Effusion Cooling Holes." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460735904.
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Kedukodi, Sandeep. "Numerical Analysis of Flow and Heat Transfer through a Lean Premixed Swirl Stabilized Combustor Nozzle." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77393.
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While the gas turbine research community is continuously pursuing development of higher cyclic efficiency designs by increasing the combustor firing temperatures and thermally resistant turbine vane / blade materials, a simultaneous effort to reduce the emission levels of high temperature driven thermal NOX also needs to be addressed. Lean premixed combustion has been found as one of the solutions to these objectives. However, since less amount of air is available for backside cooling of liner walls, it becomes very important to characterize the convective heat transfer that occurs on the inside wall of the combustor liners. These studies were explored using laboratory scale experiments as well as numerical approaches for several inlet flow conditions under both non-reacting and reacting flows. These studies may be expected to provide valuable insights for the industrial design communities towards identifying thermal hot spot locations as well as in quantifying the heat transfer magnitude, thus aiding in effective designs of the liner walls.
Lean premixed gas turbine combustor flows involve strongly coupled interactions between several aspects of physics such as the degree of swirl imparted by the inlet fuel nozzle, premixing of the fuel and incoming air, lean premixed combustion within the combustor domain, the interaction of swirling flow with combustion driven heat release resulting in flow dilation, the resulting pressure fluctuations leading to thermo-acoustic instabilities there by creating a feedback loop with incoming reactants resulting in flow instabilities leading to flame lift off, flame extinction etc. Hence understanding combustion driven swirling flow in combustors continues to be a topic of intense research.
In the present study, numerical predictions of swirl driven combustor flows were analyzed for a specific swirl number of an industrial fuel nozzle (swirler) using a commercial computational fluid dynamics tool and compared against in-house experimental data. The latter data was obtained from a newly developed test rig at Applied Propulsion and Power Laboratory (APPL) at Virginia Tech. The simulations were performed and investigated for several flow Reynolds numbers under non-reacting condition using various two equation turbulence models as well as a scale resolving model. The work was also extended to reacting flow modeling (using a partially premixed model) for a specific Reynolds number. These efforts were carried out in order investigate the flow behavior and also characterize convective heat transfer along the combustor wall (liner). Additionally, several parametric studies were performed towards investigating the effect of combustor geometry on swirling flow and liner hear transfer; and also to investigate the effect of inlet swirl on the jet impingement location along the liner wall under both non-reacting as well as reacting conditions.
The numerical results show detailed comparison against experiments for swirling flow profiles within the combustor under reacting conditions indicating a good reliability of steady state modeling approaches for reacting conditions; however, the limitations of steady state RANS turbulence models were observed for non-reacting swirling flow conditions, where the flow profiles deviate from experimental observations in the central recirculation region. Also, the numerical comparison of liner wall heat transfer characteristics against experiments showed a sensitivity to Reynolds numbers. These studies offer to provide preliminary insights of RANS predictions based on commercial CFD tools in predicting swirling, non-reacting and reacting flow and heat transfer. They can be extended to reacting flow heat transfer studies in future and also may be upgraded to unsteady LES predictions to complement future experimental observations conducted at the in-house test facility.Ph. D.
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Kao, Yi-Huan. "Experimental Investigation of Aerodynamics and Combustion Properties of a Multiple-Swirler Array." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881553.
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Greifenstein, Max [Verfasser], Andreas [Akademischer Betreuer] Dreizler, and Simone [Akademischer Betreuer] Hochgreb. "Experimental investigations of flame-cooling air interaction in an effusion cooled pressurized single sector model gas turbine combustor / Max Greifenstein ; Andreas Dreizler, Simone Hochgreb." Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/1237816939/34.
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Nachtane, Mourad. "Énergies marines renouvelables et étude des performances des matériaux composites : cas d'une hydrolienne." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0010.
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Les énergies marines renouvelables (EMR) apparaissent aujourd’hui comme une formidable opportunité et un véritable choix écologique et industriel pour répondre à la demande croissante de l’énergie et pour lutter contre le réchauffement climatique. Au cours de cette thèse, on se propose d’étudier l’un de ces types qui s’appelle l’énergie hydrolienne qui présente un immense potentiel dans le bouquet énergétique mondial. une nouvelle forme de pale d’une hydrolienne à axe horizontale a été développé par l’optimisation d’un hydrofoil existant en utilisant la méthode BEM (Blade Element Momentum) afin d’améliorer ses performances hydrodynamiques. La deuxième partie a été consacrée à étudier les performances mécaniques des matériaux composites comme composants structurels des pales d’hydrolienne et de la tuyère. Ces structures sont sujettes à de nombreux types de chargements, tels que les impacts de corps externes, la fatigue due à la variation des courants, mais également à diverses agressions liées à l’environnement marin telles que la variation de la température et l’humidité qui peuvent induire du vieillissement et de la corrosion. Une compréhension approfondie du comportement à long terme de ces parties mobiles est donc essentielle afin de doter les bureaux d’études, confrontés au dimensionnement des structures d’énergies marines, d’outils leur permettant de faire le choix des matériaux (couplefibre/matrice), architectures fibreuses (nappe, tissus), séquence d’empilement des stratifiées minimisant la sensibilité aux chargements appliqués des structures travaillantes. L’objectif final de cette thèse est le développement d’outils et de méthodologies tant numériques qu’expérimentales capables de simuler l’impact du courant et du comportement de ces systèmes de façon couplée ce qui constitue un enjeu majeur de dimensionnement. En effet le but est d’identifier les voies d’optimisation qui permettront d’aller sur la phase commerciale avec un gain de LCOE (Levelized Cost of Energy) substantielRecently, Renewable Marine Energies (RME) has emerged as a tremendous opportunity for a real ecological and industrial choice to meet the growing demands for energy and also to fight global warming. The study conducted in this thesis is with in this framework of research and is focused on the investigation of one of the most promising categories of RMEs which is tidal current turbine. A new hydrofoil for the turbine was designed using BEM (Blade Element Momentum) methods and CFD (Computational Fluid Dynamics) calculations with improved hydrodynamic efficiency. Furthermore, a series of numerical studies were conducted to investigate and examine the damage behavior of composite materials under critical loadings by developing DLOAD and VUMAT routines. This numerical study assisted in understanding the problems of structural lightening, resistance to fatigue and impact loading, and other degradation phenomena of themechanical properties of a composite turbine in severe marine environments and solving the needs of the manufactures. Moreover, study about the dynamic behavior of a composite/composite bonded assembly was also conducted because joint assembly plays a vital role in reducing the mass of the structure which is of extreme relevance in the field of marine and offshore structures. Another important obstacle regarding the application of composite and bonded structures in marine was the control of hygro-mechanical coupling. Therefore in this context, additional campaign of tests was carried out on bonded composite specimens by studying the hygrothermal effect on their dynamic behavior at different deformation rates using Hopkinson bar method. This hybrid study of hygro-thermal effect of the dynamic properties of the bonded composites will aid in optimization of the structures and to move into the commercial phase with a substantial gain in LCOE (Levelized Cost of Energy) in future
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VAGNOLI, STEFANO. "Assessment of Advanced Numerical Methods for the Aero-Thermal Investigation of Combustor-Turbine Interactions." Doctoral thesis, 2016. http://hdl.handle.net/2158/1041923.
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The individual components of modern gas turbines are optimized to such a level that any noticeable improvement of the global performance can only be the result of a significant technological effort. In this sense, one of the main strategies to increase the efficiency of new generation engines lies in the investigation of more complex but more accurate design methodologies.
In particular, the different modules of a gas turbine are historically designed separately, despite the fact that a turbomachine is a fully integrated system where all components interact with each other.
In the turbomachinery community there is a growing interest in including the interfaces between different components into the design process, as it would enable to design compressors, combustors and turbines in an integrated manner by taking into account the real operating conditions of the machine.
The interface between combustion chamber and high pressure turbine is considered as the most critical one, as it directly affects the maximum temperature reached by the thermodynamic cycle. The flow field at the combustor-turbine interface is characterized by very high turbulence levels, swirl and temperature distortions, and the CFD methods currently used to design high pressure turbine (HPT) blades lack of validation for such an aggressive environment.
The aim of the present work is to develop new numerical methodologies and to analyze the accuracy of the existing ones when applied to multi-component simulations in turbomachinery. The attention is mainly focused on the interaction between combustor and turbine, as it represents the most critical interface for a modern gas turbines.
To take into account the mutual interaction between combustion chamber and HPT, in the first part of this thesis three CFD methodologies are developed to solve the flow field of the two components in an integrated framework. The procedures are validated on test cases of increasing complexity and successfully applied to a configuration representing a modern combustion chamber coupled to a nozzle guide vane.
In the second part, the advantages and limitations of RANS and LES applied to the study of the hot streak migration in HPTs are discussed. In this sense, a LES tool for the external aerodynamics of turbine blades is developed and validated, with the aim to be applied in the future to the investigation of the combustor-turbine interaction. The accuracy of LES is
then exploited to validate less time-consuming RANS models in predicting the hot streak migration in a turbine stage.
The current investigations indicate that integrated multi-component studiesare necessary to reproduce the actual operating conditions of the different components, as the complex interaction between hot streaks, swirl, turbulence and potential effect of the NGV cannot be reproduced without resolving the combustor and turbine at the same time. Moreover, the extreme
turbulence level at the combustor-turbine interface must be modeled with care, since it plays a major role in the migration and diffusion of the hot
streak in turbine.
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Fitzpatrick, John Nathan. "Coupled thermal-fluid analysis with flowpath-cavity interaction in a gas turbine engine." Thesis, 2013. http://hdl.handle.net/1805/4441.
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Indiana University-Purdue University Indianapolis (IUPUI)This study seeks to improve the understanding of inlet conditions of a large rotor-stator cavity in a turbofan engine, often referred to as the drive cone cavity (DCC). The inlet flow is better understood through a higher fidelity computational fluid dynamics (CFD) modeling of the inlet to the cavity, and a coupled finite element (FE) thermal to CFD fluid analysis of the cavity in order to accurately predict engine component temperatures. Accurately predicting temperature distribution in the cavity is important because temperatures directly affect the material properties including Young's modulus, yield strength, fatigue strength, creep properties. All of these properties directly affect the life of critical engine components. In addition, temperatures cause thermal expansion which changes clearances and in turn affects engine efficiency. The DCC is fed from the last stage of the high pressure compressor. One of its primary functions is to purge the air over the rotor wall to prevent it from overheating. Aero-thermal conditions within the DCC cavity are particularly challenging to predict due to the complex air flow and high heat transfer in the rotating component. Thus, in order to accurately predict metal temperatures a two-way coupled CFD-FE analysis is needed. Historically, when the cavity airflow is modeled for engine design purposes, the inlet condition has been over-simplified for the CFD analysis which impacts the results, particularly in the region around the compressor disc rim. The inlet is typically simplified by circumferentially averaging the velocity field at the inlet to the cavity which removes the effect of pressure wakes from the upstream rotor blades. The way in which these non-axisymmetric flow characteristics affect metal temperatures is not well understood. In addition, a constant air temperature scaled from a previous analysis is used as the simplified cavity inlet air temperature. Therefore, the objectives of this study are: (a) model the DCC cavity with a more physically representative inlet condition while coupling the solid thermal analysis and compressible air flow analysis that includes the fluid velocity, pressure, and temperature fields; (b) run a coupled analysis whose boundary conditions come from computational models, rather than thermocouple data; (c) validate the model using available experimental data; and (d) based on the validation, determine if the model can be used to predict air inlet and metal temperatures for new engine geometries. Verification with experimental results showed that the coupled analysis with the 3D no-bolt CFD model with predictive boundary conditions, over-predicted the HP6 offtake temperature by 16k. The maximum error was an over-prediction of 50k while the average error was 17k. The predictive model with 3D bolts also predicted cavity temperatures with an average error of 17k. For the two CFD models with predicted boundary conditions, the case without bolts performed better than the case with bolts. This is due to the flow errors caused by placing stationary bolts in a rotating reference frame. Therefore it is recommended that this type of analysis only be attempted for drive cone cavities with no bolts or shielded bolts.
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CASTORRINI, ALESSIO. "Development of CAE tools for fluid-structure interaction and erosion in turbomachinery virtual prototyping." Doctoral thesis, 2017. http://hdl.handle.net/11573/940503.
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The work presented in this thesis is based on the development of advanced computer aided engineering tools dedicated to multi-physics coupled problems. Starting from the state of the art of numerical tools used in virtual prototyping and testing of turbomachinery systems, we found two interesting and actual possible developments focused on the improved implementation of fluid-structure interaction
and material wearing solvers. For both the topics we will present a brief overview with the contextualization on the industrial and research state of the art, the detailed description of mathematical models (Chapter 2), discretized (FEM) stabilized formulations, time integration schemes and coupling algorithms used in the implementation (Chapter 3). The second part of the thesis (Chapter 4-7) will
report some application of the developed tools on some latest challenges in turbomachinery field as rain erosion and load control in wind turbines and non-linear
aeroelasticity in large axial fans.
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Klapdor, Eva Verena. "Simulation of Combustor-Turbine Interaction in a Jet Engine." Phd thesis, 2011. https://tuprints.ulb.tu-darmstadt.de/2628/1/Dissertation_Klapdor.pdf.
Full textAbstract:
In the present work, “Simulation of Combustor-Turbine Interaction in a Jet Engine”, the theory and the simulation of combustor-turbine interaction in a jet engine are presented.
The objective of this thesis was the extension of a given incompressible CFD-code for the calculation of the compressible, reactive flow inside the combustor and the adjacent stator of a jet engine. The extended solver shall be used to investigate possible interaction between combustor and turbine of a jet engine.
The following two main topics were addressed:
The given incompressible solver PRECISE-UNSTRUCTURED, which is used by the combustor group of Rolls-Royce Deutschland, uses a SIMPLE procedure for the solution of the Navier-Stokes equations. This algorithm was extended with an all-Mach number formulation for the calculation of compressible flow. The implementation was verified and validated with several test cases. Comparison to analytical and experimental references showed good agreement. Simulations of a real first stator of a Rolls-Royce Deutschland jet engine were performed to demonstrate the ability of the code to calculate flow in complex geometries.
The combustion model PPDF-FGM (presumed probability density function-flamelet generated manifold) was to be used for the simulation of combustion. This model uses a stochastic mixture fraction and progress variable approach to account for chemistry-turbulence interaction. It was already available in the given code.
But the model was originally developed under the assumption of incompressible flow. Therefore, its coupling with the SIMPLE algorithm needed to be changed. A respective coupling mechanism was developed and implemented. The limiting cases, incompressible combustion and non-reactive compressible flow, were used to verify the implementation. The results using the coupled algorithm were as expected.
Finally, the developed code was used to perform an integrated simulation of a combustor and the first stator of a jet engine in one integral simulation. A second simulation without a stator was used to identify influences due to the stator on the flow in the rear part of the combustor.
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CAPPELLETTI, ALESSANDRO. "On the study of hydrogen fueling in premixed gas turbine combustor chamber." Doctoral thesis, 2013. http://hdl.handle.net/2158/794611.
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Camp, Joshua Lane. "Massively-Parallel Spectral Element Large Eddy Simulation of a Ring-Type Gas Turbine Combustor." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9404.
Full textAbstract:
The average and fluctuating components in a model ring-type gas turbine combustor are characterized using a Large Eddy Simulation at a Reynolds number of 11,000, based on the bulk velocity and the mean channel height. A spatial filter is applied to the incompressible Navier-Stokes equations, and a high pass filtered Smagorinsky model is used to model the sub-grid scales. Two cases are studied: one with only the swirler inlet active, and one with a single row of dilution jets activated, operating at a momentum flux ratio J of 100. The goal of both of these studies is to validate the capabilities of the solver NEK5000 to resolve important flow features inherent to gas turbine combustors by comparing qualitatively to the work of Jakirlic. Both cases show strong evidence of the Precessing Vortex Core, an essential flow feature in gas turbine combustors. Each case captures other important flow characteristics, such as corner eddies, and in general predicts bulk flow movements well. However, the simulations performed quite poorly in terms of predicting turbulence shear stress quantities. Difficulties in properly emulating the turbulent velocity entering the combustor for the swirl, as well as mesh quality concerns, may have skewed the results. Overall, though small length scale quantities were not accurately captured, the large scale quantities were, and this stress test on the HPF LES model will be built upon in future work that looks at more complex combustors.
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INSINNA, MASSIMILIANO. "Investigation of the Aero-Thermal Aspects of Combustor/Turbine Interaction in Gas Turbines." Doctoral thesis, 2015. http://hdl.handle.net/2158/986426.
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Taso, Jhy-Ming, and 曹志明. "Prediction on The Interaction of Swirl Flow and Jet In a Gas Turbine-Combustor." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/58283033385393404423.
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Santos, Daniela Filipa Martins. "Combustion of CH4, H2, and CH4 -H2 Mixtures in a Gas Turbine Can Combustor." Master's thesis, 2014. http://hdl.handle.net/10400.6/6451.
Full textAbstract:
The fact that there is an increase in the price of fossil fuels, and that environmental changes are occurring due to pollutant emissions, makes it imperative to find alternative fuels that are less polluting and cheaper.
Gas turbines have been particularly developed as aviation engines, but nowadays they can find applicability in many areas and the fact that they have multiple fuel applications, makes them a very important subject of study.
The main objective of this dissertation is to evaluate through a CFD analysis on FLUENT the performance of the combustion in a gas turbine can combustor, fed with methane, hydrogen and methane-hydrogen mixtures taking a particular interest in the pollutants emissions.
In the end a fuel optimization was carried on to evaluate the average mass fraction of the pollutants CO, CO2 and NOx at the exit of the can combustor, and also a brief evaluation of the static temperature and pressure, and velocity magnitude in the several CFD simulations was executed.O facto do preço dos combustíveis fósseis estar cada vez mais elevado, e de estarem a ocorrer mudanças ambientais devido à emissão de poluentes por parte destes combustíveis torna imperativo encontrar combustíveis alternativos mais baratos e menos poluentes. As turbinas de gás têm sido particularmente desenvolvidas como motores de aeronaves, no entanto nos dias que correm elas podem encontrar aplicabilidade nas mais diversas áreas, e aliando a isto o facto das turbinas de gás possuírem diferentes aplicabilidades de combustíveis faz delas um importante tema de estudo. Sendo assim o principal objectivo desta dissertação é avaliar através de uma análise CFD no FLUENT o desempenho da combustão num ?can combustor? de uma turbina de gás, quando alimentado com metano, hidrogénio e misturas de metano-hidrogénio, tendo especial interesse na emissão de poluentes. Posto isto foi realizada uma optimização do combustível por forma a avaliar os valores médios da fracção mássica dos poluentes CO, CO2 e NOx à saída do "can combustor", e de notar que uma breve análise à temperatura estática, à pressão estática e à magnitude da velocidade das várias simulações foi também executada.
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Cubeda, Simone. "Impacts of gas-turbine combustors outlet flow on the aero-thermal performance of film-cooled first stage nozzles." Doctoral thesis, 2020. http://hdl.handle.net/2158/1197567.
Full textAbstract:
Modern aero-engine and industrial gas turbines typically employ lean-type combustors, which are capable of limiting pollutant emissions thanks to premixed flames, while sustaining high turbine inlet temperatures that increase the single-cycle thermal efficiency. In such technology gas-turbine first stage nozzles are characterised by a highly-swirled and temperature-distorted inlet flow field. However, due to several sources of uncertainty during the design phase, wide safety margins are commonly adopted, which can have a direct impact on the engine performance and efficiency.
Therefore, with the aim of increasing the knowledge on combustor-turbine interaction and improving standard design practices, two non-reactive test rigs were assembled at the University of Florence, Italy. The rigs, both accommodating three lean-premix swirlers within a combustion chamber and a first stage film-cooled nozzles cascade, were operated in similitude conditions to mimic an aero-engine and an industrial gas turbine arrangements. The rigs were designed to reproduce the real engine periodic flow field on the central sector, allowing also to perform measurements far enough from the lateral walls. The periodicity condition was enforced by the installation of circular ducts at the injectors outlet section as to preserve the non-reactive swirling flow down to the nozzles inlet plane.
For the aero-engine simulator rig and as part of two previous PhD works, of which the present is a continuation, an extensive test campaign was conducted. The flow field within the combustion chamber was investigated via particle-image velocimetry (PIV) and the combustor-turbine interface section was experimentally characterised in terms of velocity, pressure and turbulence fields by means of a five-hole pressure plus thermocouple probe and hot-wire anemometers, mounted on an automatic traverse system. To study the evolution of the combustor outlet flow through the nozzles and its interaction with the film-cooling flow, such measurements have been also replicated slightly downstream of the airfoils' trailing edge. Lastly, the film-cooling adiabatic effectiveness distribution over the airfoils was evaluated via coolant concentration measurements based on pressure sensitive paints (PSP) application. As far as the industrial turbine rig is concerned, the same type of measurements were carried out except for PIV.
Within such experimental scenario, the core of the present work is related to numerical analyses. In fact, since the design of industrial high-pressure turbines historically relies on 1D, circumferentially-averaged profiles of pressure, velocity and temperature at the combustor/turbine interface in conjunction with Reynolds-averaged Navier-Stokes (RANS) models, this thesis describes how measurements can be leveraged to improve numerical modelling procedures. Within such context, hybrid scale resolving techniques, such as Scale-Adaptive Simulation (SAS), can suit the purpose, whilst containing computational costs, as also shown in the literature. Furthermore, the investigation of the two components within the same integrated simulation enables the transport of unsteady fluctuations from the combustor down to the first stage nozzles, which can make the difference in the presence of film cooling.
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LIN, YU-HUI, and 林育暉. "Application of ANSYS CFX in Wind Turbine fluid-structure interaction Simulation." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/99917313165364828549.
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碩士中華大學
機械工程學系
105
In recent years with the country's active development of renewable energy and development and research, and wind power is a kind of renewable energy, but also the world is committed to the development of renewable energy. Taiwan's western coastal and outer islands have considerable wind resources, the average annual wind speed of up to 5 ~ 6 m/s above the density of 250 w/m2, showing that China has a wind turbine development of shallow power. In this study, the structural analysis software ANSYS was used to analyze the structural mechanics behavior of the 660 kW Vestas V47 trilobalic horizontal shaft fan at the wind speed (15 m/s). In the study, Workbench under ANSYS was used to analyze the fluid-structure coupling, that is, the computational fluid dynamics software CFX and ANSYS structural mechanics software were combined with each other. And according to the relationship between different pitch angle, tilt angle and wind speed, different terrain corresponds to the ground roughness coefficient α. In addition to the general external flow field, the portion of the flow field region establishes a circular rotational domain flow field in the blade rotor section, since the setting of the blade portion during the calculation of the fluid analysis is to rotate, The wind speed is based on the wind velocity distribution method of IEC61400-1. The formula is Vinlet = Vhub (Z / Hhub) α, and the response of the blade to the fluid-solid coupling is discussed. The results are analyzed. Part of the speed in the first model has the maximum value, YZ plane under the maximum value will appear in the third model, the rotation field pressure field and YZ plane pressure field maximum is appear in the third model, Structural stress maximum value In addition to the first model is present on the left side of the blade, the other two models are present on the right side of the blade, and the maximum value appears on the first model. This study hopes to study the distribution of the flow field, the distribution of the pressure field and the stress distribution of the structure, and then the noise problem is discussed.
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MAZZEI, LORENZO. "A 3D coupled approach for the thermal design of aero-engine combustor liners." Doctoral thesis, 2015. http://hdl.handle.net/2158/993808.
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The recent limitations imposed by ICAO-CAEP towards a drastic reduction of NOx emissions is driving the development of modern aeroengines towards the implementation of lean burn concept. The increased amount of air dedicated to the combustion process (up to 70%) involves several technological issues, including a signicant reduction of coolant available for the thermal management of combustor liners. This, from a design perspective, involves the continuous research for effective cooling schemes, such as effusion cooling, and the necessity of more accurate methodologies for the estimation of metal temperature, so as to properly assess the expected duration of hot gas path components.
The flame stabilization through swirler characterized by large effective area leads to extended recirculating zones, which interact considerably with the liner cooling system. As highlighted in the first part of this dissertation, the impact on the near-wall flow field makes any consideration based on a correlative approach untrustworthy, demanding for more reliable evaluations through CFD analysis. Unfortunately, the application of effusion cooling entails a huge computational effort due to the high number of film cooling holes involved, therefore many approaches have been proposed in literature with the aim of modelling the coolant injection through mass sources.
This work presents SAFE (Source based effusion model), a methodology for the CFD simulation of the entire combustor, which is based on the local coolant injection through point sources and a calculation of mass flow rate according to local flow conditions. A further step in reduction in the computational effort is represented by a different methodology, called Therm3D, which involves the simulation of the flame tube, whereas the solution of the remaining part of the combustor is fulfilled through the modelling of an equivalent flow network, which provides for the estimation of flow split and cold side heat loads.
Ultimately, this work introduces innovative approaches for the CFD investigation of effusion cooled combustor, with a special focus on the metal temperature prediction. A model for the film cooling injection is proposed to overcome the issues related to the necessity of meshing the perforation, nevertheless several improvable aspects have been highlighted, pointing the way for further enhancements.
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Greifenstein, Max. "Experimental investigations of flame-cooling air interaction in an effusion cooled pressurized single sector model gas turbine combustor." Phd thesis, 2021. https://tuprints.ulb.tu-darmstadt.de/19205/2/greifenstein_dissertation_210726_urn_uri.pdf.
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Within this thesis, the mutual interaction between the flame and cooling air within an effusion cooled single sector model gas turbine combustor is investigated at elevated pressure.
Although effusion cooling has been widely studied in the last decades with respect to heat transfer and total film cooling effectiveness, fundamental aspects of the interaction mechanisms with the reacting main flow are not yet well understood.
Typically, experimental investigations are conducted either by reducing the complexity by placing an effusion cooling plate in a test section downstream of a hot gas source, which allows a good experimental accessibility and well controlled boundary conditions, or by reducing the complexity on the diagnostics side, e.g. by using sampling probe measurements at the exhaust of a close-to-reality test rig.
The first approach does not facilitate investigations of the interaction mechanisms between the reacting main flow and effusion cooling air, as they are spatially separated.
The second approach on the other hand includes all mechanisms, but measurements are not conducted spatially resolved within the test section.
Within this work, an effusion cooling plate is mounted within a generic test rig which features a swirl-stabilized turbulent flame at elevated inlet temperature and pressure to fully capture the influence of unsteady heat release, convection, radiation and chemical reactions in the vicinity of the liner.
Quantitative and semi-quantitative advanced laser diagnostics with high temporal and spatial resolution are employed to identify sensitivities of flame-cooling air interaction with respect to important boundary conditions that affect the flow and temperature field and cooling performance.
Mixing between the reacting main flow and effusion cooling air is investigated by a combination of quantitative planar laser-induced fluorescence of the hydroxyl radical (OH) and nitric oxide, seeded to the effusion cooling air.
This data allows to identify the relative occurrence of mixing processes before, during and after reaction.
Furthermore, measurements of the thermochemical state, as represented by the carbon monoxide (CO) mole fraction and the gas phase temperature, were conducted using combined quantitative CO laser induced fluorescence (LIF) and ro-vibrational coherent anti-Stokes Raman spectroscopy with nitrogen as a resonant species.
Simultaneous LIF measurements of OH, CO and formaldehyde (CH2O) were executed to investigate the sensitivity of CO production and oxidation near reaction zones to the boundary conditions.
The acquired data shows that interaction processes between the flame and cooling air locally influence the structure of the premixed flame across the preheating zone, main reaction zone and the exhaust.
Spatially, these interaction processes are not limited to the area close to the effusion cooled liner but extend into the primary zone by recirculation.
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Lenzi, Tommaso. "EXPERIMENTAL CHARACTERIZATION OF THE UNSTEADY INTERACTION BETWEEN EFFUSION COOLING AND SWIRLING FLOWS IN A GAS TURBINE COMBUSTOR MODEL." Doctoral thesis, 2021. http://hdl.handle.net/2158/1238640.
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The analysis of the interaction between the swirling and cooling flows, promoted by the liner film cooling system, is a fundamental task for the design of turbine combustion chambers since it influences different aspects such as emissions and cooling capability. The requirements for improving the modern gas turbine combustors are: swirler injectors for flame stabiliza- tion, increasingly higher temperature and pressure values, and an increased amount of air dedicated to the combustion process. All these aspects make the design of even more efficient cooling systems, and the correct estimation of liners heat load, a hard task. Experimental works in the literature have addressed the problem with dedicated test rigs using steady-state measure- ment techniques to analyze the interaction between swirling main flow and effusion cooling flow. However, the fluid dynamic mechanisms, which govern turbulent mixing between main and coolant, are the flow field instabilities. In particular high turbulence oscillations, eddies, and tangential velocity com- ponents induced by the swirling flow deeply affect the behavior of effusion cooling jets demanding for dedicated unsteady flow field (near-wall coolant sub-layer) and adiabatic effectiveness experimental analysis. For this reason the present research activity is aimed at an unsteady characterization of the turbulent interaction between effusion cooling and swirling flows in a gas turbine combustor model. The experimental setup of this work consists of a non-reactive single-sector linear combustor test rig scaled up with respect to engine dimensions to increase spatial resolution and reduce the frequencies of the unsteadiness. The test section was equipped with an effusion plate with standard inclined cylindrical holes to simulate the liner cooling system. The degree of swirl for a swirling flow is usually characterized by the swirl number, Sn, defined as the ratio of the tangential momentum flux to axial momentum flux. To assess the impact of such parameter on the near-wall effusion behavior, a set of three different axial swirlers with swirl number equal to Sn = 0.6 - 0.8 - 1.0 were designed and tested in the experimental apparatus. The tests were also carried out by varying the feeding pressure drop of the effusion plate to evaluate the effect of this parameter.
During the first phase of the research, the rig was instrumented with a 2D Time-Resolved Particle Image Velocimetry system, focussing on different field of views. An analysis of the main flow field by varying the Sn was first performed in terms of average velocity, Root Mean Square, and turbulence related quantities like kinetic energy spectra and length scale information. In a second step, the analysis was focussed on the near-wall regions: the impact of Sn on the coolant jets was quantified in terms of vorticity analysis and jet oscillation, highlighting a strong effect of the swirl number on film behav- ior. Subsequently, film effectiveness was acquired using the Fast Response Pressure Sensitive Paint technique; the scale of the model and the acquisi- tion frequency allowed to track the effusion jets unsteadiness. With both the measurement techniques, the collected results show the importance of using an unsteady analysis to perform an in-depth characterization of the mixing phenomena between the main flow and the coolant, which in significantly affected by the Sn value.
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Bertini, Davide. "High-fidelity prediction of metal temperature in gas turbine combustors using a loosely coupled multiphysics approach." Doctoral thesis, 2019. http://hdl.handle.net/2158/1155985.
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Aeroengine industry is being largely affected by the mid- and long-term targets of civil aviation, that is searching for increasingly efficient low-emission engines and new opportunities as in the segment of small aircraft. The dynamically evolving market requires prompt solutions for the combustor that cannot be easily provided by experiments because of technical issues and expensive campaigns. On the other hand, the progressive developments in the field of massively parallel computing is making Computational Fluid Dynamics the most effective tool for a deep insight of combustion chambers. Indeed, high-fidelity investigations on this component is a multiphysics problem requiring to model the interactions between turbulence, combustion, radiation and heat transfer. Thermal design is a key task in the development loop of novel combustors, being stressed by lower coolant availability and higher power density. For this purpose, CFD-based models are required to properly account for the 3-D heat load distribution. Nevertheless, the limits of standard RANS approaches in accurately modelling highly-turbulent reacting flow is well-known and nowadays scale-resolving methods, as Large-Eddy Simulation (LES), Detached Eddy Simulation (DES) and Scale Adaptive Simulation (SAS), are the most promising ones; the latter, in particular, is emerged as a valid trade-off for industrial applications.
In the present work a multiphysics tool, called U-THERM3D, is proposed as potential approach for the prediction of metal temperature in the context of scale-resolving simulations. The tool is validated on predictable solutions and applied to two burners, the DLR model aero-engine combustor and the LEMCOTEC combustor. The former is a laboratory sooting flame simulated using LES and the focus is on the tool capabilities in modelling the involved interacting phenomena. The latter is an effusion cooled lean-burn aeroengine combustor investigated from different perspectives using SAS to predict exit profile temperature, emissions and metal temperature.
To the author's knowledge no works can be found in literature on multiphysics simulations of lean burn combustors relying on Scale Adaptive Simulation. For this reason the present work aims to be a reference for high-fidelity final design as well as a starting point for future activities.
The results in both the burners are compared against steady THERM3D simulations and experiments emphasizing the detrimental effects of the swirling flow on the wall temperature, that acts increasing the heat transfer coefficient and reducing the film cooling coverage.
The improved prediction of metal temperature obtained by U-THERM3D shows the potential of this tool as a framework for the high-fidelity design of gas turbine combustors. Obviously, the accuracy of the coupled simulation can benefit from the improvement in the different involved models and further research efforts should be focused on this task.
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Bacci, Tommaso. "Experimental investigation on a high pressure NGV cascade in the presence of a representative lean burn aero-engine combustor outflow." Doctoral thesis, 2018. http://hdl.handle.net/2158/1128260.
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Experimental Investigation of the effects of a modern lean burn combustor outflow on the performance of a film-cooled NGV cascade. Evaluation of chamber flow field, NGV inlet/outlet aerothermal field, turbulence decay and adiabatic effectiveness on the NGV profiles