Dissertations / Theses on the topic 'Gas turbine combustion chambers'
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Kister, Guillaume. "Ceramic-matrix composites for gas turbine applications." Thesis, University of Bath, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299850.
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Cavaliere, Davide Egidio. "Blow-off in gas turbine combustors." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/265575.
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This thesis describes an experimental investigation of the flame structure close to the extinction and the blow-off events of non-premixed and spray flames stabilized on an axisymmetric bluff body in a confined swirl configuration. The comparison of flames of different canonical types in the same basic aerodynamic field allows insights on the relative blow-off behaviour. The first part of the thesis describes several velocity measurements in non-reacting and reacting flows. The main usefulness of this data is to provide the aerodynamic flow pattern and some discussion on the velocity field and the related recirculation zones. The velocity and turbulence information obtained are particularly useful for providing data, which is crucial for validation of computational models. The second part describes an experimental investigation of non-premixed stable flames very close to the blow-off condition. The measurements included visualisation of the blow-off transient with 5 kHz OH* chemiluminescence, which allowed a quantification of the average duration of the blow-off transient. OH-PLIF images at 5 kHz for flames far from and close to extinction showed that the non-premixed flame intermittently lifts-off the bluff body, with increasing probability as the fuel velocity increases. The flame sheet shows evidence of localised extinctions, which are more pronounced as approaching blow-off. The measurements include blow-off limits and their attempted correlation. It was found that a correlation based on a Damkohler number does a reasonable job at collapsing the dataset. The final part examines the blow-off behaviour of swirling spray flames for two different fuels: n-heptane and n-decane. The measurements include blow-off limits and their att~mpted correlation, visualisation of the blow-off transient with 5 kHz OH* chemiluminescence, and the quantification of the average duration of the blow-off transient. It was found that the average duration of the blow-off event is in order of the tens of ms for both spray flames (10-16 ms). The blow-off event is therefore a relatively slow process for the spray ~ames using n-heptane and decane fuels. This suggests that control measures, such as fast fuel injection, coupled with appropriate detection, such as with chemiluminescence monitoring, may have a reasonable chance of success in keeping the flame alight very close to the blow-off limit. These results, together with those obtained for the non-premixed gaseous case form a wide body of experimental data available for the validation of turbulent flame models. The quantification of some properties during the blow-off transient can assist studies of extinction based on large-eddy simulation that have a promise of capturing combustion transients.
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Bainbridge, William David Quillen. "The numerical similation of oscillations in gas turbine combustion chambers." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648428.
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Fortunato, Valentina. "Development and testing of combustion chambers for residential micro gas turbine applications." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/256708.
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Nowadays, in the field of energy production, particular attention must be paid to improving efficiency, reducing pollutants and fuel flexibility. To reach those goals, cogenerative systems represent an appealing solution. One of the most promising cogenerative systems available nowadays is the micro turbine, which provides reasonable electrical efficiency of about 30%, multi-fuel capability, low emission levels and heat recovery potential, and need minimum maintenance. Among the several options, micro gas turbines (mGT) are particularly interesting. Beside theuse of natural gas, other fuels like landfill gas, ethanol, industrial waste off-gases and other bio-based gases can be used. Moreover, it is possible to further improve the efficiencies and reduce the emissions for mGTs by paying particular attention at the design of the combustion chamber. To this goal, flameless combustion could be an interesting solution. Flameless combustion is able to provide high combustion efficiency with low NOx and soot emissions. The increasing interest in flameless combustion is motivated by its large fuel flexibility, representing a promising technology for low-calorific value fuels, high-calorific industrial wastes as well as in presence of hydrogen. Moreover, flameless combustion is very stableand noiseless, so it is suited for gas turbine applications where conventional operations may lead to significant thermo-acoustic instabilities (“humming”) and stresses. Flameless combustion needs the reactants to be preheated above their self-ignition temperature and enough inert combustion products to be entrained in the reaction region, in order to dilute the flame. As a result, the temperature field is more uniform than in traditional combustion systems, and it does not show high temperature peaks. Hence, NOx formation is suppressed as well as soot formation,due to the lean conditions, low temperatures and the large CO2 concentration in the exhausts.mGTs operating in flameless combustion regime represent a promising technology for the combined production of heat and power with increased efficiency, reduced pollutants emission and high fuel flexibility. The objective of the present Thesis is the design of a combustion chamber for amGT for residential applications. The design is performed employing CFD-tools. Thus, it is necessary to develop a reliable numerical model to use in the design process. Therefore, the first step of the Thesis consists in a series of validation studies, with the goal of selecting the most appropriate and reliable models to describe flameless combustion. The validation will be carried on three differenttest cases, which have different nominal powers and employ different gaseous fuels. The second part of the Thesis focuses on the design and optimization of the combustion chamber. Finally, the third part shows the experimental investigation of the aforementioned chamber.The study of those three cases shows that, to correctly predict the behavior of those systems, it is necessary to take into account both mixing and chemical kinetics. The best results have been obtained with the Eddy Dissipation Concept model, coupled with detailed kinetic schemes. As far as the NOx emissions are concerned, it is fundamental to include all the formation routes, i.e. thermal, prompt, via N2O and NNH route, to estimate properly the NOx production in flameless conditions.The aforementioned models have been used for the design and optimization of a combustion chamber for a mGT operating in flameless combustion regime. Both the design and the optimization have been carried out by means of CFD simulations and both are goal-oriented, meaning that they are carried out with the purpose of improving one or more performance indicators of the chamber, such as pollutants emissions, efficiency or pressure losses. The configuration that satisfies the criteria on the performance indicators has been built and investigated experimentally. The combustion chamber is stable and performs well in terms of emissions for a wide range of air inlet temperature and air-fuel equivalence ratio, lambda, values. Except for the condition closer to the stoichiometric one, both CO and NOx emissions are extremely low for all !and air inlet temperatures. Thechamber performs the best at its nominal operating condition, i.e. lambda = 3.5 and air inlet temperature 730 °C, In this case CO is 0 ppm and NOx is 5.6 ppm. The numerical model employed to describe the combustor performs quite well, except for the CO prediction, for all the conditions investigated. The final step of the present work is the application of a different kind of fuel, namely biogas. First the feasibility of such application has been evaluated using CFD calculations, and then the experimental evidence has been discussed. Due to a calibration error on the gas flow meter, it has not been possible to investigate the conditions of the design point (lambda = 3.5). Three other conditions have been examined,characterized by lower values of !closer to the stoichiometric conditions. Despite the relatively high values of NOx emissions due to the lower air excess and to the consequently higher temperatures, the combustion chamber has proven to be fuel flexible. Both ignition and stable combustion can be achieved also when biogas is burnt. Numerical simulations have also been performed; the results are in good agreement with the experimental evidence.Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
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Ku, Shiuh-Huei. "An investigation of the gas fired pulsating combustor." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/13062.
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Farrell, Brian Henry. "An experimental and theoretical investigation into simple, low cost combustion chambers for small gas turbines." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335334.
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Neumeier, Yedidia. "Frequency domain analysis of a gas fired mechanically valved pulse combustor." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/13354.
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Robinson, Alexander. "Development and testing of hydrogen fuelled combustion chambers for the possible use in an ultra micro gas turbine." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209706.
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The growing need of mobile power sources with high energy density and the robustness to operate also in the harshest environmental surroundings lead to the idea of downscaling gas turbines to ì-scale. Classified as PowerMEMS devices, a couple of design attempts have emerged in the last decade. One of these attempts was the Belgian “PowerMEMS” design started back in 2003 and aiming towards a ì-scale gas turbine rated at 1 kW of electrical power output.This PhD thesis presents the scientific evaluation and development history of different combustion chamber designs based upon the “PowerMEMS” design parameters. With hydrogen as chosen fuel, the non-premixed diffusive “micromix” concept was selected as combustion principle. Originally designed for full scale gas turbine applications in two different variants, consequently the microcombustor development had to start with the downscaling of these two principles towards ì-scale. Both principles have the advantage to be inherently safe against flashback, due to the non-premixed concept, which is an important issue even in this small scale application when burning hydrogen. By means of water analogy and CFD simulations the hydrogen injection system and the chamber geometry could be validated and optimized. Besides the specific design topics that emerged during the downscaling process of the chosen combustion concepts, the general difficulties of microcombustor design like e.g. high power density, low Reynolds numbers, short residence time, and manufacturing restrictions had to be tackled as well.
As full scale experimental test campaigns are still mandatory in the field of combustion research, extensive experimental testing of the different prototypes was performed. All test campaigns were conducted with a newly designed test rig in a combustion lab modified for microcombustion investigations, allowing testing of miniaturized combustors according to full engine requirements with regard to mass flow, inlet temperature, and chamber pressure. The main results regarding efficiency, equivalence ratio, and combustion temperature were obtained by evaluating the measured exhaust gas composition. Together with the performed ignition and extinction trials, the evaluation and analysis of the obtained test results leads to a full characterization of each tested prototype and delivered vital information about the possible operating regime in a later UMGT application. In addition to the stability and efficiency characteristics, another critical parameter in combustor research, the NOx emissions, was investigated and analyzed for the different combustor prototypes.
As an advancement of the initial downscaled micromix prototypes, the following microcombustor prototype was not only a combustion demonstrator any more, but already aimed for easy module integration into the real UMGT. With a further optimized combustion efficiency, it also featured an innovative recuperative cooling of the chamber walls and thus allowing an cost effective all stainless steel design.
Finally, a statement about the pros and cons of the different micromix combustion concepts and their correspondent combustor designs towards a possible ì-scale application could be given.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Mohanraj, Rajendran. "Modeling of combustion instabilities and their active control in a gas fueled combustor." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/12089.
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Lieuwen, Tim C. "Investigation of combustion instability mechanisms in premixed gas turbines." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20300.
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Hummel, Tobias [Verfasser]. "Modeling and Analysis of High-Frequency Thermoacoustic Oscillations in Gas Turbine Combustion Chambers / Tobias Hummel." München : Verlag Dr. Hut, 2019. http://d-nb.info/118151424X/34.
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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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Barringer, Michael David. "Design and Benchmarking of a Combustor Simulator Relevant to Gas Turbine Engines." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35519.
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An experimental facility was designed and benchmarked that could simulate the non-uniformities in the flow and thermal fields exiting real gas-turbine combustors. The design of the combustor simulator required analyses of the flow paths within a real combustor in a gas turbine engine. Modifications were made to an existing wind tunnel facility to allow for the installation of the combustor simulator. The overall performance of the simulator was then benchmarked through measurements of velocity, pressure, temperature, and turbulence using a straight exit test section to provide a baseline set of data. Comparisons of the measured quantities were made between two test cases that included a flow field with and without dilution flow.One of the major findings from this study was that the total pressure profiles exiting the combustor simulator in the near-wall region were different from a turbulent boundary layer. This is significant since many studies consider a turbulent boundary layer as the inlet condition to the turbine. Turbulent integral length scales were found to scale well with the dilution hole diameters and no dominant frequencies were observed in the streamwise velocity energy spectra. Dilution flow resulted in an increase in turbulence levels and mixing causing a reduction in the variation of total pressure and velocity. Adiabatic effectiveness levels were significantly reduced for the case with dilution flow in both the near combustor exit region and along the axial length of the straight exit test section.Master of Science
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Lee, John C. Y. "Reduction of NOx emission for lean prevaporized-premixed combustors /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7035.
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Yaqub, Sarmad. "Experimental investigation of flame dynamics in an industrial gas turbine combustion chamber." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488996.
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The experimental investigation of the combustion dynamics in a full scale industrial gas turbine combustor has been conducted. The successful capture of different combustion observables; including chemiluminescence emissions from C2* and CH* radicals, acoustic pressure oscillations emanating from the combustor, sound pressure level, fuel pressure oscillations before entry to the combustor, differential pressure oscillations across orifice plates for fuel flow measurement has yielded a huge database.
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Birmaher, Shai. "A method for aircraft afterburner combustion without flameholders." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28081.
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Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Chair: Zinn, Ben; Committee Member: Fuller, Thomas; Committee Member: Gaeta, Rick; Committee Member: Jagoda, Jeff; Committee Member: Neumeier, Yedidia
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Wolf, Pierre. "Large Eddy Simulation of thermoacoustic instabilities in annular combustion chambers." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0111.
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La conception des turbines à gaz est aujourd'hui contrainte par des normes d'émissions de plus en plus draconiennes, couplées à l'urgente nécessité d'économiser les ressources en carburant fossile. Les choix technologiques adoptés pour répondre à ces exigences entraînent parfois l'apparition d'instabilités de combustion. Dans les chambres de combustion annulaires, ces instabilités prennent souvent la forme de modes azimutaux. Prédire ces modes reste un défi à l'heure actuelle et impose de considérer la totalité de la géométrie annulaire, ce qui n'est rendu possible, dans le domaine de la simulation numérique en mécanique des fluides, que par l'avènement très récent des supercalculateurs massivement parallèles. Dans ce travail de thèse, les modes azimutaux pouvant apparaître dans les chambres de combustion annulaires sont abordés avec plusieurs approches: un modèle analytique 1D, un solveur acoustique de Helmholtz 3D et enfin des Simulations aux Grandes Echelles. Combiner ces méthodes permet une meilleure compréhension de la structure de ces modes et peut amener à considérer des solutions innovantes pour concevoir des chambres inconditionnellement stablesIncreasingly stringent regulations and the need to tackle rising fuel prices have placed great emphasis on the design of aeronautical gas turbines. This drive towards innovation has resulted sometimes in new concepts being prone to combustion instabilities. Combustion instabilities arise from the coupling of acoustics and combustion. In the particular field of annular combustion chambers, these instabilities often take the form of azimuthal modes. To predict these modes, one must consider the full combustion chamber, which, in the numerical simulation domain, remained out of reach until very recently and the development of massively parallel computers. In this work, azimuthal modes that may develop in annular combustors are studied with different numerical approaches: a low order model, a 3D Helmholtz solver and Large Eddy Simulations. Combining these methods allows a better understanding of the structure of the instabilities and may provide guidelines to build intrinsically stable combustion chambers
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Bobba, Mohan Krishna. "Flame stabilization and mixing characteristics in a stagnation point reverse flow combustor." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26502.
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Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2008.Committee Chair: Seitzman, Jerry; Committee Member: Filatyev, Sergei; Committee Member: Jagoda, Jechiel; Committee Member: Lieuwen, Timothy; Committee Member: Shelton, Samuel; Committee Member: Zinn, Ben. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Reichling, Gilles [Verfasser], and Manfred [Akademischer Betreuer] Aigner. "Development of numerical methods for the calculation of thermo-acoustic interactions in gas turbine combustion chambers / Gilles Reichling. Betreuer: Manfred Aigner." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2015. http://d-nb.info/1072073056/34.
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Cosic, Bernhard [Verfasser], Christian Oliver [Akademischer Betreuer] Paschereit, and Nicolas [Akademischer Betreuer] Noiray. "Nonlinear thermoacoustic stability analysis of gas turbine combustion chambers / Bernhard Cosic. Gutachter: Christian Oliver Paschereit ; Nicolas Noiray. Betreuer: Christian Oliver Paschereit." Berlin : Technische Universität Berlin, 2015. http://d-nb.info/1067388281/34.
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Crawford, Jackie H. III. "Factors that limit control effectiveness in self-excited noise driven combustors." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43647.
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A full Strouhal number thermo-acoustic model is purposed for the feedback control of self excited noise driven combustors. The inclusion of time delays in the volumetric heat release perturbation models create unique behavioral characteristics which are not properly reproduced within current low Strouhal number thermo acoustic models. New analysis tools using probability density functions are introduced which enable exact expressions for the statistics of a time delayed system. Additionally, preexisting tools from applied mathematics and control theory for spectral analysis of time delay systems are introduced to the combustion community. These new analysis tools can be used to extend sensitivity function analysis used in control theory to explain limits to control effectiveness in self-excited combustors. The control effectiveness of self-excited combustors with actuator constraints are found to be most sensitive to the location of non-minimum phase zeros. Modeling the non-minimum phase zeros correctly require accurate volumetric heat release perturbation models. Designs that removes non-minimum phase zeros are more likely to have poles in the right hand complex plane. As a result, unstable combustors are inherently more responsive to feedback control.
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Acharya, Vishal Srinivas. "Dynamics of premixed flames in non-axisymmetric disturbance fields." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50213.
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With strict environmental regulations, gas turbine emissions have been heavily constrained. This requires operating conditions wherein thermo-acoustic flame instabilities are prevalent. During this process the combustor acoustics and combustion heat release fluctuations are coupled and can cause severe structural damage to engine components, reduced operability, and inefficiency that eventually increase emissions. In order to develop an engine without these problems, there needs to be a better understanding of the physics behind the coupling mechanisms of this instability. Among the several coupling mechanisms, the “velocity coupling” process is the main focus of this thesis.
The majority of literature has treated axisymmetric disturbance fields which are typical of longitudinal acoustic forcing and axisymmetric excitation of ring vortices. Two important non-axisymmetric disturbances are: (1) transverse acoustics, in the case of circumferential modes of a multi-nozzle annular combustor and (2) helical flow disturbances, seen in the case of swirling flow hydrodynamic instabilities. With significantly less analytical treatment of this non-axisymmetric problem, a general framework is developed for three-dimensional swirl-stabilized flame response to non-axisymmetric disturbances. The dynamics are tracked using a level-set based G-equation applicable to infinitely thin flame sheets. For specific assumptions in a linear framework, general solution characteristics are obtained. The results are presented separately for axisymmetric and non-axisymmetric mean flames.
The unsteady heat release process leads to an unsteady volume generation at the flame front due to the expansion of gases. This unsteady volume generation leads to sound generation by the flame as a distributed monopole source. A sound generation model is developed where ambient pressure fluctuations are generated by this distributed fluctuating heat release source on the flame surface. The flame response framework is used to provide this local heat release source input. This study has been specifically performed for the helical flow disturbance cases to illustrate the effects different modes have on the generated sound. Results show that the effects on global heat release and sound generation are significantly different.
Finally, the prediction from the analytical models is compared with experimental data. First, a two-dimensional bluff-body stabilized flame experiment is used to obtain measurements of both the flow and flame position in time. This enables a local flame response comparison since the data are spatially resolved along the flame. Next, a three-dimensional swirl-stabilized lifted flame experiment is considered. The measured flow data is used as input to the G-equation model and the global flame response is predicted. This is then compared with the corresponding value obtained using global CH* chemilumenescence measurements.
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Wang, Hongjuan. "Simulation of fuel injectors excited by synthetic microjets." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/11862.
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Fortier-Topping, Hugo. "Conception d'une chambre de combustion pour la microturbine à gaz SRGT-2." Mémoire, Université de Sherbrooke, 2014. http://hdl.handle.net/11143/5417.
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Dans un contexte mondial où les ressources énergétiques commencent à se faire rares, beaucoup de recherches se font sur l’amélioration de l’efficacité thermique et de la densité de puissance des sources d’énergie existantes. Ainsi, un projet de développement d’une microturbine à gaz avec une architecture de nouveau genre permettant d’augmenter la densité de puissance tout en réduisant les coûts a vu le jour.
La recherche proposée dans le présent document se concentre sur la conception et la caractérisation d’une chambre de combustion et d’un banc d’essai pour la turbine SRGT-2.
Une chambre de combustion à écoulement inverse est conçue et caractérisée expérimentalement. Un modèle 0D de la chambre est tout d’abord fait. Par la suite, une optimisation numérique est faite jusqu’à l’atteinte des objectifs de conception. Finalement, la chambre de combustion est testée durant 30 secondes avec de l’hydrogène comme carburant. Une température de sortie de la chambre de combustion de 1000 K a été maintenue avec une efficacité de combustion de plus de 85%.
Le banc d’essai conçu pour le projet de recherche utilise un démarreur électropneumatique permettant d’accélérer le prototype jusqu’à 102 000 RPM. Le module fluide est la partie du banc d’essai qui contient les différentes parties de la turbine SRGT-2 comme le rotor, les stators et la chambre de combustion. Le module est instrumenté dans le but d’obtenir une caractérisation complète de la turbine. Sa configuration modulaire permet aussi de caractériser chacune des composantes individuellement en changeant certaines sections.
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Gibson, R. E. N. "The design of a catalytic combustion chamber for a gas turbine using woodgas as a fuel." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426730.
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Pinto, Daniel Vieira. "Análise comparativa do desempenho de turbocompressores veiculares com câmara de combustão tubular na microgeração de energia." reponame:Repositório Institucional da UCS, 2017. https://repositorio.ucs.br/handle/11338/3253.
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Esta dissertação de mestrado apresenta o desenvolvimento de um trabalho que tem como objetivos avaliar a composição de turbocompressores veiculares para microgeração de energia e desenvolver um modelo de câmara de combustão tubular para equipar microturbinas a gás derivadas de turbocompressores. No desenvolvimento do trabalho, utilizando o software Cycle-Tempo, foi feita a avaliação de possíveis configurações de microturbinas a gás derivadas de turbocompressores, no que diz respeito ao número de eixos e dispositivos de aumento de eficiência térmica (intercooler, recuperador de calor e reaquecedor). No total foram simuladas, dez diferentes configurações, sendo que as análises foram feitas diretamente nos parâmetros de eficiência térmica dos conjuntos avaliando-se a relação entre a energia aportada pelo combustível e a energia entregue num gerador elétrico hipotético. Na sequência são definidos os turbocompressores para compor uma determinada configuração de microturbina a gás e, para tanto, utilizaram-se os mapas de desempenho dos turbocompressores de um fabricante. A partir dos parâmetros de operação dos equipamentos foi desenvolvido um modelo tridimensional de câmara de combustão em software de CAD. O modelo passou por cinco etapas de simulações em Dinâmica dos Fluidos Computacional (Computational Fluid Dynamics - CFD). As primeiras três etapas serviram para desenvolver e aprimorar o modelo tridimensional de câmara de combustão e, por limitações do software, não envolveram combustão. Utilizando condições de contorno operacionais, foram avaliados: o perfil de velocidades ao longo da câmara de combustão, a perda de pressão, a intensidade da turbulência, a homogeneização entre os reagentes ar e combustível e a divisão do fluxo mássico em cada seção da câmara de combustão. A partir do modelo tridimensional foi desenvolvido um protótipo da câmara de combustão, construído a partir de tubos comerciais de PVC. O protótipo foi avaliado experimentalmente com escoamento do ar a temperatura ambiente, utilizando o acoplamento em série entre um ventilador centrífugo e um soprador. No experimento foi avaliada a divisão de fluxo mássico de ar em cada seção da câmara de combustão e a perda de pressão. As simulações CFD foram refeitas na quarta etapa, onde as condições de contorno foram os parâmetros de fluxo mássico, pressão e temperatura, obtidos experimentalmente. Com isto, pode ser feita a comparação direta entre os resultados obtidos experimentalmente e os resultados das simulações CFD. Concluindo o trabalho foi realizada a quinta etapa, onde foi inserida uma fonte de calor simulando o aporte de energia da combustão, permitindo a avaliação da temperatura na câmara de combustão. As simulações CFD indicaram resultados semelhantes ao que é previsto em bibliografia, no que diz respeito à divisão do fluxo mássico, perda de pressão e à distribuição de velocidades. Já as avaliações experimentais apresentaram incerteza de medição elevada para a divisão de fluxo mássico. Quanto à perda de pressão o método experimental mostrou-se adequado.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2017-10-25T17:02:08Z No. of bitstreams: 1 Dissertacao Daniel Vieira Pinto.pdf: 7889874 bytes, checksum: a3dd417da94a3175c511cb73b3577fd2 (MD5)
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This master's work presents the development of a work that has the objective of evaluating the composition of vehicular turbochargers for microgeneration of energy and to develop a tubular combustion chamber model to equip gas microturbines derived from turbochargers. In the development of the work, using the software Cycle-Tempo, it is made the evaluation of possible configurations of gas micro turbines derived from turbochargers, with respect to the number of axes and devices of increasing thermal efficiency (intercoolers, heat recover e reheater). In total, ten different configurations were simulated, and the analyzes were done directly in the thermal efficiency parameters of the sets, evaluating the relation between the energy contributed by the fuel and the energy delivered in a hypothetical electric generator. Turbochargers are then defined to form a particular gas micro turbine configuration and, being used the turbocharger performance maps from a manufacturer. From the operating parameters of the equipment, a three-dimensional combustion chamber model was developed in CAD software. The model went through five stages of simulations in Computational Fluid Dynamics (CFD). The first three steps served to develop and improve the three-dimensional model of combustion chamber and, due to software limitations, did not involve combustion. Using operational contour conditions, the velocity profile along the combustion chamber, the pressure loss, the turbulence intensity, the homogenization between the air and fuel reactants and the division of the mass flow in each section of the combustion chamber were evaluated. From the three-dimensional model was developed a prototype of the combustion chamber, built from commercial PVC pipes. The prototype was evaluated experimentally with air flow at room temperature using the coupling in series between a centrifugal fan and a blower. In the experiment the air mass flow division in each section of the combustion chamber and the loss of pressure were evaluated. The CFD simulations were redone in the fourth stage, where the boundary conditions were the parameters of mass flow, pressure and temperature, obtained experimentally. Thus, a direct comparison between the results obtained experimentally and the results of CFD simulations can be made. At the end of the work the fifth step was performed, where a heat source was inserted simulating the energy input of the combustion, allowing the temperature evaluation in the combustion chamber. The CFD simulations indicated results similar to those predicted in the literature, regarding the division of mass flow, pressure loss and velocity distribution. However, the experimental evaluations presented high measurement uncertainty for the mass flow division. Regarding pressure loss, the experimental method proved to be adequate.
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Šíblová, Kamila. "Návrh spalovací turbíny pro osobní automobil." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230622.
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This diploma thesis deals about the combustion turbine, design, processing and utilization. This work can be divided into three parts. The first part focuses on the theoretical knowledge gained in the field of gas turbines and their applications. The second part addresses the design of combustion turbine and its integral part. The third section describes the expected characteristics of combustion turbines. The work also includes the annex, which includes the technical documentation.
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Zhang, Qingguo. "Lean blowoff characteristics of swirling H2/CO/CH4 Flames." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22641.
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This thesis describes an experimental investigation of lean blowoff for H2/CO/CH4 mixtures in a swirling combustor. This investigation consisted of three thrusts. The first thrust focused on correlations of the lean blowoff limits of H2/CO/CH4 mixtures under different test conditions. It was found that a classical Damköhler number approach with a diffusion correction could correlate blowoff sensitivities to fuel composition over a range of conditions.
The second part of this thesis describes the qualitative flame dynamics near blowoff by systematically characterizing the blowoff phenomenology as a function of hydrogen level in the fuel. These near blowoff dynamics are very complex, and are influenced by both fluid mechanics and chemical kinetics; in particular, the role of thermal expansion across the flame and extinction strain rate were suggested to be critical in describing these influences.
The third part of this thesis quantitatively analyzed strain characteristics in the vicinity of the attachment point of stable and near blowoff flames. Surprisingly, it was found that in this shear layer stabilized flame, flow deceleration is the key contributor to flame strain, with flow shear playing a relatively negligible role. Near the premixer exit, due to strong flow deceleration, the flame is negatively strained i.e., compressed. Moving downstream, the strain rate increases towards zero and then becomes positive, where flames are stretched. As the flame moves toward blowoff, holes begin to form in the flame sheet, with a progressively higher probability of occurrence as one moves downstream. It is suggested that new holes form with a more uniform probability, but that this behavior reflects the convection of flame holes downstream by the flow.
It has been shown in prior studies, and affirmed in this work, that flames approach blowoff by first passing through a transient phase manifested by local extinction events and the appearance of holes on the flame. A key conclusion of this work is that the onset of this boundary occurs at a nearly constant extinction strain rate. As such, it is suggested that Damköhler number scalings do not describe blowoff itself, but rather the occurrence of this first stage of blowoff. Given the correspondence between this first stage and the actual blowoff event, this explains the success of classical Damköhler number scalings in describing blowoff, such as shown in the first thrust of this thesis. The physics process associated with the actual blowoff event is still unclear and remains a key task for future work.
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Rubensdörffer, Frank G. "Numerical and Experimental Investigations of Design Parameters Defining Gas Turbine Nozzle Guide Vane Endwall Heat Transfer." Doctoral thesis, KTH, Energiteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3884.
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The primary requirements for a modern industrial gas turbine consist of a continuous trend of an increasing efficiency combined with very low emissions in a robust, cost-effective manner. To fulfil these tasks a high turbine inlet temperature together with advanced dry low NOX combustion chambers are employed. These dry low NOX combustion chambers generate a rather flat temperature profile compared to previous generation gas turbines, which have a rather parabolic temperature profile before the nozzle guide vane. This means that the nozzle guide vane endwall heat load for modern gas turbines is much higher compared to previous generation gas turbines. Therefore the prediction of the nozzle guide vane flow field and endwall heat transfer is crucial for the engineering task of the design layout of the vane endwall cooling system. The present study is directed towards establishing new in-depth aerodynamic and endwall heat transfer knowledge for an advanced nozzle guide vane of a modern industrial gas turbine. To reach this objective the physical processes and effects which cause the different flow fields and the endwall heat transfer pattern in a baseline configuration, a combustion chamber variant, a heat shield variant without and with additional cooling air and a cavity variant without and with additional cooling air have been investigated. The variants, which differ from the simplified baseline configuration, apply design elements which are commonly used in real modern gas turbines. This research area is crucial for the nozzle guide vane endwall heat transfer, especially for the advanced design of the nozzle guide vane of a modern industrial gas turbine and has so far hardly been investigated in the open literature. For the experimental aerodynamic and endwall heat transfer research of the baseline configuration of the advanced nozzle guide vane geometry a new low pressure, low temperature test facility has been developed, designed and constructed, since no experimental heat transfer data exist in the open literature for this type of vane configuration. The new test rig consists of a linear cascade with the baseline configuration of the advanced nozzle guide vane geometry with four upscaled airfoils and three flow passages. For the aerodynamic tests the two middle airfoils and the hub and the tip endwall are instrumented with pressure taps to monitor the Mach number distribution. For the heat transfer tests the temperature distribution on the hub endwall is measured via thermography. The analysis of these measurements, including comparisons to research in the open literature shows that the new test rig generates accurate and reproducible results which give confidence that it is a reliable tool for the experimental aerodynamic and heat transfer research on the advanced nozzle guide vane of a modern industrial gas turbine. Previous own research work together with the numerical analysis performed in another part of the project as well as conclusions from a detailed literature study lead to the conclusion that advanced Navier-Stokes CFD tools with the v2-f turbulence model are most suitable for the calculation of the flow field and the endwall heat transfer of turbine vanes and blades. Therefore this numerical tool, validated against different vane and blade geometries and for different flow conditions, has been chosen for the numerical aerodynamic and endwall heat transfer research of the advanced nozzle guide vane of a modern industrial gas turbine. The evaluation of the numerical and experimental investigations of the baseline configuration of the advanced design of a nozzle guide vane shows the flow field of an advanced mid-loaded airfoil design with the features to reduce total airfoil losses. For the hub endwall of the baseline configuration of the advanced design of a nozzle guide vane the flow characteristics and heat transfer features of the classical vane endwall secondary flow model can be detected with a very weak intensity and geometric extension compared to the studies of less advanced vane geometries in the open literature. A detailed analysis of the numerical simulations and the experimental data showed very good qualitative and quantitative agreement for the three-dimensional flow field and the endwall heat transfer. These findings, together with the evaluations obtained from the open literature, lead to the conclusions that selected CFD software Fluent together with the applied v2-f turbulence model exhibits a high level of general applicability and is not tuned to a special vane or blade geometry. Therefore the CFD code Fluent with the v2-f turbulence model has been selected for the research of the influence of the several geometric variants of the baseline configuration on the flow field and the hub endwall heat transfer of the advanced nozzle guide vane of a modern industrial gas turbine. Most of the vane endwall heat transfer research in the open literature has been carried out only for baseline configurations of the flow path between combustion chamber and nozzle guide vane. Such a simplified geometry consists of a long, planar undisturbed approach length upstream of the nozzle guide vane. The design of real modern industrial gas turbines however requires often significant variations from this baseline configuration consisting of air-cooled heat shields and purged cavities between the combustion chamber and the nozzle guide vane. A detailed evaluation of the flow field and the endwall heat transfer shows major differences between the baseline and the heat shield configuration. The heat shield in front of the airfoil of the nozzle guide vane influences the secondary flow field and the endwall heat transfer pattern strongly. Additional cooling air, released under the heat shield has a distinctive influence as well. Also the cavity between the combustion chamber and the nozzle guide vane affects the secondary flow field and the endwall heat transfer pattern. Here the influence of additional cavity cooling air is more decisive. The results of the detailed studies of the geometric variants are applied to formulate guidelines for an optimized design of the flow path between the combustion chamber and the nozzle guide vane and the nozzle guide vane endwall cooling configuration of next-generation industrial gas turbines.QC 20100917
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Natarajan, Jayaprakash. "Experimental and numerical investigation of laminar flame speeds of H₂/CO/CO₂/N₂ mixtures." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22685.
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Coal derived synthetic gas (syngas) fuel is a promising solution for today s increasing demand for clean and reliable power. Syngas fuels are primarily mixtures of H2 and CO, often with large amounts of diluents such as N2, CO2, and H2O. The specific composition depends upon the fuel source and gasification technique. This requires gas turbine designers to develop fuel flexible combustors capable of operating with high conversion efficiency while maintaining low emissions for a wide range of syngas fuel mixtures. Design tools often used in combustor development require data on various fundamental gas combustion properties. For example, laminar flame speed is often an input as it has a significant impact upon the size and static stability of the combustor. Moreover it serves as a good validation parameter for leading kinetic models used for detailed combustion simulations.
Thus the primary objective of this thesis is measurement of laminar flame speeds of syngas fuel mixtures at conditions relevant to ground-power gas turbines. To accomplish this goal, two flame speed measurement approaches were developed: a Bunsen flame approach modified to use the reaction zone area in order to reduce the influence of flame curvature on the measured flame speed and a stagnation flame approach employing a rounded bluff body. The modified Bunsen flame approach was validated against stretch-corrected approaches over a range of fuels and test conditions; the agreement is very good (less than 10% difference). Using the two measurement approaches, extensive flame speed information were obtained for lean syngas mixtures at a range of conditions: 1) 5 to 100% H2 in the H2/CO fuel mixture; 2) 300-700 K preheat temperature; 3) 1 to 15 atm pressure, and 4) 0-70% dilution with CO2 or N2.
The second objective of this thesis is to use the flame speed data to validate leading kinetic mechanisms for syngas combustion. Comparisons of the experimental flame speeds to those predicted using detailed numerical simulations of strained and unstrained laminar flames indicate that all the current kinetic mechanisms tend to over predict the increase in flame speed with preheat temperature for medium and high H2 content fuel mixtures. A sensitivity analysis that includes reported uncertainties in rate constants reveals that the errors in the rate constants of the reactions involving HO2 seem to be the most likely cause for the observed higher preheat temperature dependence of the flame speeds. To enhance the accuracy of the current models, a more detailed sensitivity analysis based on temperature dependent reaction rate parameters should be considered as the problem seems to be in the intermediate temperature range (~800-1200 K).
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Ahmad, N. T. "Swirl stabilised gas turbine combustion." Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356423.
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Andrews, G. E. "Gas turbine combustion with low emissions." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329381.
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Söderberg, Jakob. "CAE of Gas Turbine Combustor Chamber : Improving workflow in product lifecycle management systems." Thesis, Linköpings universitet, Maskinkonstruktion, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-168687.
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This thesis seeks to improve the workflow in the product development process when using the Product Lifecycle Management (PLM) system PLM2020, incorporated at Siemens Energy. Focus is on three problem cases that emerge when working with Computer Aided Engineering (CAE) data during the development process. Apart from solving these problems, a current situation analysis was conducted, and possible solutions of these problems were investigated on how they affect the lead time in the product development process. The problems consist of exploration of an unused function and solving of two problematic situations that can occur while using PLM2020 during development work. A case study was established to investigate the problems, using participatory observations and interviews. The interviews established the current situation of Siemens work methodology to handle these situations and how PLM2020 is used. During the observations, the problems were attempted to be solved using an arbitrary Computer Aided Design (CAD) model while exploring different functions in a sandbox environment. During the interviews, it was discovered that there exist different ways of working in PLM2020 and that some approaches nullifies the benefits of using a PLM system. The participatory observations revealed that that there exist functions in the PLM system that solves the problems encountered. A set of proposed solutions are presented to Siemens
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Chleboun, Peter Victor. "Mathematical modelling relevant to gas turbine combustion." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343286.
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Uyanwaththa, Asela R. "CFD modelling of gas turbine combustion processes." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/34686.
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Stationary gas turbines manufacturers and operators are under constant scrutiny to both reduce environmentally harmful emissions and obtain efficient combustion. Numerical simulations have become an integral part of the development and optimisation of gas turbine combustors. In this thesis work, the gas turbine combustion process is analysed in two parts, a study on air-fuel mixing and turbulent combustion. For computational fluid dynamic analysis work the open-source CFD code OpenFOAM and STAR-CCM+ are used. A fuel jet injected to cross-flowing air flow is simplified air-fuel mixing arrangement, and this problem is analysed numerically in the first part of the thesis using both Reynolds Averaged Navier Stokes (RANS) method and Large Eddy Simulation (LES) methods. Several turbulence models are compared against experimental data in this work, and the complex turbulent vortex structures their effect on mixing field prediction is observed. Furthermore, the numerical methods are extended to study twin jets in cross-flow interaction which is relevant in predicting air-fuel mixing with arrays of fuel injection nozzles. LES methods showed good results by resolving the complex turbulent structures, and the interaction of two jets is also visualised. In this work, all three turbulent combustion regimes non-premixed, premixed, partially premixed are modelled using different combustion models. Hydrogen blended fuels have drawn particular interest recently due to enhanced flame stabilisation, reduced CO2 emissions, and is an alternative method to store energy from renewable energy sources. Therefore, the well known Sydney swirl flame which uses CH4: H2 blended fuel mixture is modelled using the steady laminar flamelet model. This flame has been found challenging to model numerically by previous researchers, and in this work, this problem has been addressed with improved combustion modelling approach with tabulated chemistry. Recognizing that the current and future gas turbine combustors operate on a mixed combustion regime during its full operational cycle, combustion simulations of premixed/partially premixed flames are also performed in this thesis work. Dynamical artificially thickened flame model is implemented in OpenFOAM and validated using propagating and stationary premixed flames. Flamelet Generated Manifold (FGM) methods are used in the modelling of turbulent stratified flames which is a relatively new field of under investigation, and both experimental and numerical analysis is required to understand the physics. The recent experiments of the Cambridge stratified burner are studied using the FGM method in this thesis work, and good agreement is obtained for mixing field and temperature field predictions.
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Engelbrecht, Geoffrey E. "Modelling of premixed combustion in a gas turbine." Thesis, Cranfield University, 1998. http://hdl.handle.net/1826/3987.
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Three steady state combustion models, two turbulence models and a model for tK'6
prediction of NO., were implemented and investigated on a simple backward facing
step experiment as well as an experimental lean prevaporised premixed (LPP)
combustor. The three combustion models included the simple Eddy Break-up model
as well as a presumed probability density function (pdf) model and a form of the BML
crossing frequency flamelet model. These models were adapted to consider a
variable mixture fraction to account for a non-homogeneous fuel air mixture. The
two turbulence models used were the k-e and second moment models.
Despite being unable to capture the flame front spreading in the case of the
backward facing step, these predictions provided insight into the performance and
implementation of the models. All three of the combustion models, after appropriate
tuning, worked well for the LPP test combustor. This illustrates that such time
averaged models are useful for flows which do not contain large transient coherent
structures, such as that of the LPP test combustor and most practical engine
combustors designed today. The second moment closure turbulence model was
found to have the greatest impact on the flame front through the flow field predictions
rather than through counter gradient diffusion. The Eddy Break-up and BML
crossing frequency models both performed very well, qualitatively predicting the
correct trends. The additional consideration of flame front straining in the BML
crossing frequency model did not appear to significantly influence the flame front.
This is because the type of model adopted to predict this effect had a relatively
uniform influence everywhere in the flow. The presumed pdf model also performed
well and was additionally found to self ignite without the existence of hot products
when the inlet temperature was high enough. The NO., model faired well for a simple
experimental geometry. However, it considerably over predicted the NO., formed
within the LIPP test combustor, which was most probably due to poor boundary
conditions. Despite this overprediction, the results give insight into how to improve
the NQ, emissions for the experimental combustor.
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MacCallum, N. R. L. "Studies in gas turbine performance and in combustion." Thesis, University of Glasgow, 2000. http://theses.gla.ac.uk/5335/.
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Eccles, Neil C. "Structured grid generation for gas turbine combustion systems." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/7348.
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Commercial pressures to reduce time-scales encourage innovation in the design and analysis cycle of gas turbine combustion systems. The migration of Computational Fluid Dynamics (CFD) from the purview of the specialist into a routine analysis tool is crucial to achieve these reductions and forms the focus of this research. Two significant challenges were identified: reducing the time-scale for creating and solving a CFD prediction and reducing the level of expertise required to perform a prediction. The commercial pressure for the rapid production of CFD predictions, coupled with the desire to reduce the risk associated with adopting a new technology led, following a review of available techniques, to the identification of structured grids as the current optimum methodology. It was decided that the task of geometry definition would be entirely performed within commercial Computer Aided Design (CAD) systems. A critical success factor for this research was the adoption of solid models for the geometry representation. Solids ensure consistency, and accuracy, whilst eliminating the need for the designer to undertake difficult, and time consuming, geometry repair operations. The versatility of parametric CAD systems were investigated on the complex geometry of a combustion system and found to be useful in reducing the overhead in altering the geometry for a CFD prediction. Accurate and robust transfer between CAD and CFD systems was achieved by the use of direct translators. Restricting the geometry definition to solid models allowed a novel two stage grid generator to be developed. In stage one an initial algebraic grid is created. This reduces user interaction to a minimum, by the employment of a series of logical rules based on the solid model to fill in any missing grid boundary condition data. In stage two the quality of the grid is improved by redistributing nodes using elliptical partial differential equations. A unique approach of improving grid quality by simultaneously smoothing both internal and surface grids was implemented. The smoothing operation was responsible for quality, and therefore reduced the level of grid generation expertise required. The successful validation of this research was demonstrated using several test cases including a CFD prediction of a complete combustion system.
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Abdul, Aziz M. M. "Liquid fuelled jet shear layer gas turbine combustion." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233835.
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Zhang, K. "Turbulent combustion simulation in realistic gas-turbine combustors." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/17689/.
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The work presented in this thesis addresses issues involving the accurate and efficient numerical modelling of turbulence combustion with an emphasis on an industrially representative Tay model combustor. This combustor retained all essential features of a modern aero-engine rich burn combustor and thus the turbulence combustion within this combustor is much more complicated than those observed in the combustor-like burners typically considered in laboratory experiments. A comparative study of two combustion models based on a non-premixed assumption or a partially premixed assumption using the previously proposed models Zimont Turbulent Flame Speed Closure (ZTFSC) and Extended Coherent Flamelet Method (ECFM)) is presented in a first step. Comprehensive chemical reactions containing 244 reactions and 50 species are taken into account using a tabulated detailed chemistry approach and an assumed shape PDF to account for turbulence effects. The purpose of this study is to validate and compare the effectiveness of these models in predicting complex combustion and to improve upon for the defects observed in previous predictions of the same combustor. It is concluded that the use of models invoking the partially premixed combustion assumption can provide much more accurate results than models using a non-premixed combustion assumption especially in the primary zone of the combustor where turbulence combustion interaction is strong. In addition, certain shortcomings of steady RANS type models are identified as a result of strong unsteady effects and their inability to resolve the turbulence spectrum. Following this, two URANS models and the scale resolving simulation (SRS) approach such as a shear stress transport, K-omega, scale adaptive simulation (SSTKWSAS) combined with the partially premixed method identified in the first step are employed in a second step to further improve the accuracy achieved and to provide evidence and guidance in terms of the trade-off between accuracy and computational cost for complex turbulent combustion simulations. The second generation SRS model (SSTKWSAS) is applied to the complicated flow environment of a realistic combustor for the first time. The present work highlights the superiority of the combination of the SSTKWSAS approach and a partially premixed combustion model in terms of both accuracy and efficiency for predicting such combustion problems.
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Al-Kabie, Hisham Salman. "Radial swirlers for low emissions gas turbine combustion." Thesis, University of Leeds, 1989. http://etheses.whiterose.ac.uk/21157/.
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Radial swirler were investigated for gas turbine combustor applications. with low NOx emissions as the main aim of the project. The flow regime of the combustor which was imposed by the radial swirler flow was shown by flow visualisation to feature a conical shaped swirling shear layer boundary and a comer recirculation zone. The flow patterns was independent of the swirl-vane angle but was a function of the swirler passage depth. A minimum swirler expansion ratio of 1.8 was required to achieve an adequate combustion efficiency. A high efficiency was not achieved in the weak region until there was a significant outer expansion and associated recirculation zone. However, there was a little influence of the expansion ratio on the weak extinction limit. Various non-conventional fuel injection methods such as swirler vane passage. radial central and wall injection were used with gaseous propane and natural gas and liquid kerosene and gasoil. Passage injection was undertaken to exploit the twin benefits of peripheral fuel injection and partial fuel and air mixing upstream of the swirlers outlet. Generally, most of the mixing between fuel/air took place in the shear layer. However, there was a major influence of the method of fuel injection on the NOx emissions. Low NOx emissions were achieved with the radial central injection, but ultra-low NOx emissions, comparable with the premixed situation, were achieved for passage and wall injection. This was due to the dependency of the local shear layer mixing near the swirler exit on the fuel placement as shown by the radial gas analysis traverse results in the plane just downstream of the radial swirler. Staged air and fuel combustion was investigated using lean-lean combustion concept. Low NOx emissions compatible with a high combustion efficiency was demonstrated with stable switching from pilot to main stage combustion. Finally, a double radial swirler with a high air flow was investigated using co and counter swirl and demonstrated ultra low NOx with a good stability with central injection into counter rotating swirler. These systems were shown to have the potential for dry solution to the industrial gas turbine NOx emissions regulations with a very high combustion efficiency.
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Bednář, František. "Analýza možností akumulační tepelné elektrárny v podmínkách ČR." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231650.
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This diploma’s thesis analyzes the possibility of accumulation of thermal power plants in the Czech Republic. The thesis is divided into several parts. The first part describes the different types of storage power plants, the historical development of power storage for compressed air and the appropriateness of their location. The second part is devoted to the design of storage power plant for compressed air in South Moravia. In the next chapter, a calculation is made of all equipment storage power plant, including turbo-compressor, combustion chamber, combustion turbines, the volume of storage tanks and two heat exchangers. The last part is the economic analysis of the return on investment of such a project.
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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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Johansson, Magnus. "Catalytic combustion of gasified biomass for gas turbine applications." Doctoral thesis, KTH, Chemical Engineering and Technology, 1998. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2701.
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Catalytic combustion is an ultra-low emission technology forgas turbines. In parallel to the ongoing development andcommercialization of catalytic combustors fired by naturalgas,an increasing interest is aimed towards renewables, such asgasified biomass. Gasified biomass is a low-heating value (LHV)fuel, rich in hydrogen and carbon monoxide, with apotentiallyhigh level of ammonia. Consequently, specialconsiderations must be taken in the development of catalyticgas turbine combustors with gasified biomass as fuel.The first part of the present thesis reports onfundamental phenomena related to catalyticcombustion ofgasified biomass for gas turbine applications. Successfuldevelopment of the catalyst involves knowledge of both gasturbine technology and gasification of biomass.Therefore, basicconsiderations applied to integration of gasification and gasturbinetechnology are discussed. Moreover, formation ofnitrogen oxide emissions in combustion isdiscussed and asummary of the appended papers is given. Finally, recentdevelopments incatalytic combustion in gas turbines arereviewed in Paper I in the present thesis.
The second part of the present thesis, Papers II-VIII,concerns preparation and testing ofpotential combustioncatalysts. The objectives of this work have been focused onpreparationmethods and development of thermally stable andactive hexaaluminate-based catalysts (Papers II, IV-VII),ignition of the LHV-gas (Papers III-VII), conversion offuel-bound nitrogen(Papers III, V-VI) and deactivation bythermal treatment and sulphur poisoning (PapersVI-VII).Moreover, enhancing catalytic activity for totaloxidation of methane through doping ofceria has been studied(Paper VIII). The experimental investigation included activitytesting inbench-scale monolithic, single-channel annular andfixed bed reactors, and characterisationsuch as BET, XRD, SEM,EDX, XPS and SIMS.
In conclusion, lanthanum hexaaluminate impregnated with lowloading of palladiumignites the LHV-fuel at temperaturesbetween 200-250°C. At even lower palladium loading highconversion rates of carbon monoxide and hydrogen were stillobtained, while methaneconversion decreased substantially.Thermal stability and sulphur resistance of thepalladiumcatalyst exceeds those of similar platinum andtransition metal catalysts, with respect toignition of carbonmonoxide and hydrogen. Modification of the hexaaluminate phase,i.e. byion-substitution with manganese or iron, increasescatalytic activity and stability of the crystalphase, althoughsurface areas were equal to or smaller than those forunsubstituted samples.The conversion of ammonia to nitrogenoxides or molecular nitrogen (N2) was influenced by the inlettemperature and the catalyst composition. A high selectivity toN2 was observed in certain temperature regimes; higher overcatalysts based on manganese than on palladium
KEYWORDS:Catalytic combustion, gasified biomass, gasturbines, low-heating value, methanefuel-nitrogen,hexaaluminate, Pd, Pt, base metals, CeO2, deactivation, sulphurpoisoning,
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Prashanth, Prakash. "Post-combustion emissions control for aero-gas turbine engines." Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/122402.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-50).
Aviation NO[subscript x] emissions have an impact on air quality and climate change, where the latter is magnified due to the higher sensitivity of the upper troposphere and lower stratosphere. In the aviation industry, efforts to increase the efficiency of propulsion systems are giving rise to higher overall pressure ratios which results in higher NO[subscript x] emissions due to increased combustion temperatures. This thesis identifies that the trend towards smaller engine cores (gas generators) that are power dense and contribute little to the thrust output presents new opportunities for emissions control that were previously unthinkable when the core exhaust stream contributed significant thrust. This thesis proposes and assesses selective catalytic reduction (SCR), which is a post-combustion emissions control method used in ground-based sources such as power generation and heavy-duty diesel engines, for use in aero-gas turbines.
The SCR system increases aircraft weight and introduces a pressure drop in the core stream. The effects of these are evaluated using representative engine cycle models provided by a major aero-gas turbine manufacturer. This thesis finds that employing an ammonia-based SCR can achieve close to 95% reduction in NO[subscript x] emissions for ~0.4% increase in block fuel burn. The large size of the catalyst needs to be housed in the body of the aircraft and hence would be suitable for future designs where the engine core is also within the fuselage, such as would be possible with turbo-electric or hybrid-electric designs. The performance of the post-combustion emissions control is shown to improve for smaller core engines in new aircraft in the NASA N+3 time-line (2030-2035), suggesting the potential to further decrease the cost of the ~95% NO[subscript x] reduction to below ~0.4% fuel burn.
Using a global chemistry and transport model (GEOS-Chem) this thesis estimates that using ultra-low sulfur (<15 ppm fuel sulfur content) in tandem with post-combustion emissions control results in a ~92% reduction in annual average population exposure to PM₂.₅ and a ~95% reduction in population exposure to ozone. This averts approximately 93% of the air pollution impact of aviation.
by Prakash Prashanth.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Ndiaye, Aïssatou. "Uncertainty Quantification of Thermo-acousticinstabilities in gas turbine combustors." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS062/document.
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Les instabilités thermo-acoustiques résultent de l'interaction entre les oscillations de pression acoustique et les fluctuations du taux de dégagement de chaleur de la flamme. Ces instabilités de combustion sont particulièrement préoccupantes en raison de leur fréquence dans les turbines à gaz modernes et à faible émission. Leurs principaux effets indésirables sont une réduction du temps de fonctionnement du moteur en raison des oscillations de grandes amplitudes ainsi que de fortes vibrations à l'intérieur de la chambre de combustion. La simulation numérique est maintenant devenue une approche clé pour comprendre et prédire ces instabilités dans la phase de conception industrielle. Cependant, la prédiction de ce phénomène reste difficile en raison de sa complexité; cela se confirme lorsque les paramètres physiques du processus de modélisation sont incertains, ce qui est pratiquement toujours le cas pour des systèmes réels.Introduire la quantification des incertitudes pour la thermo-acoustique est le seul moyen d'étudier et de contrôler la stabilité des chambres de combustion qui fonctionnent dans des conditions réalistes; c'est l'objectif de cette thèse.Dans un premier temps, une chambre de combustion académique (avec un seul injecteur et une seule flamme) ainsi que deux chambres de moteurs d'hélicoptère (avec N injecteurs et des flammes) sont étudiés. Les calculs basés sur un solveur de Helmholtz et un outil quasi-analytique de bas ordre fournissent des estimations appropriées de la fréquence et des structures modales pour chaque géométrie. L'analyse suggère que la réponse de la flamme aux perturbations acoustiques joue un rôle prédominant dans la dynamique de la chambre de combustion. Ainsi, la prise en compte des incertitudes liées à la représentation de la flamme apparaît comme une étape nécessaire vers une analyse robuste de la stabilité du système.Dans un second temps, la notion de facteur de risque, c'est-à-dire la probabilité pour un mode thermo-acoustique d'être instable, est introduite afin de fournir une description plus générale du système que la classification classique et binaire (stable / instable). Les approches de modélisation de Monte Carlo et de modèle de substitution sont associées pour effectuer une analyse de quantification d'incertitudes de la chambre de combustion académique avec deux paramètres incertains (amplitude et temps de réponse de la flamme). On montre que l'utilisation de modèles de substitution algébriques réduit drastiquement le nombre de calculs initiales, donc la charge de calcul, tout en fournissant des estimations précises du facteur de risque modal. Pour traiter les problèmes multidimensionnel tels que les deux moteurs d'hélicoptère, une stratégie visant à réduire le nombre de paramètres incertains est introduite. La méthode <> combinée à une approche de changement de variables a permis d'identifier trois directions dominantes (au lieu des N paramètres incertains initiaux) qui suffisent à décrire la dynamique des deux systèmes industriels. Dès lors que ces paramètres dominants sont associés à des modèles de substitution appropriés, cela permet de réaliser efficacement une analyse de quantification des incertitudes de systèmes thermo-acoustiques complexes.Finalement, on examine la perspective d'utiliser la méthode adjointe pour analyser la sensibilité des systèmes thermo-acoustiques représentés par des solveurs 3D de Helmholtz. Les résultats obtenus sur des cas tests 2D et 3D sont prometteurs et suggèrent d'explorer davantage le potentiel de cette méthode dans le cas de problèmes thermo-acoustiques encore plus complexesThermoacoustic instabilities result from the interaction between acoustic pressure oscillations and flame heat release rate fluctuations. These combustion instabilities are of particular concern due to their frequent occurrence in modern, low emission gas turbine engines. Their major undesirable consequence is a reduced time of operation due to large amplitude oscillations of the flame position and structural vibrations within the combustor. Computational Fluid Dynamics (CFD) has now become one a key approach to understand and predict these instabilities at industrial readiness level. Still, predicting this phenomenon remains difficult due to modelling and computational challenges; this is even more true when physical parameters of the modelling process are uncertain, which is always the case in practical situations. Introducing Uncertainty Quantification for thermoacoustics is the only way to study and control the stability of gas turbine combustors operated under realistic conditions; this is the objective of this work.First, a laboratory-scale combustor (with only one injector and flame) as well as two industrial helicopter engines (with N injectors and flames) are investigated. Calculations based on a Helmholtz solver and quasi analytical low order tool provide suitable estimates of the frequency and modal structures for each geometry. The analysis suggests that the flame response to acoustic perturbations plays the predominant role in the dynamics of the combustor. Accounting for the uncertainties of the flame representation is thus identified as a key step towards a robust stability analysis.Second, the notion of Risk Factor, that is to say the probability for a particular thermoacoustic mode to be unstable, is introduced in order to provide a more general description of the system than the classical binary (stable/unstable) classification. Monte Carlo and surrogate modelling approaches are then combined to perform an uncertainty quantification analysis of the laboratory-scale combustor with two uncertain parameters (amplitude and time delay of the flame response). It is shown that the use of algebraic surrogate models reduces drastically the number of state computations, thus the computational load, while providing accurate estimates of the modal risk factor. To deal with the curse of dimensionality, a strategy to reduce the number of uncertain parameters is further introduced in order to properly handle the two industrial helicopter engines. The active subspace algorithm used together with a change of variables allows identifying three dominant directions (instead of N initial uncertain parameters) which are sufficient to describe the dynamics of the industrial systems. Combined with appropriate surrogate models construction, this allows to conduct computationally efficient uncertainty quantification analysis of complex thermoacoustic systems.Third, the perspective of using adjoint method for the sensitivity analysis of thermoacoustic systems represented by 3D Helmholtz solvers is examined. The results obtained for 2D and 3D test cases are promising and suggest to further explore the potential of this method on even more complex thermoacoustic problems
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Rice, Matthew Jason. "Simulation of Isothermal Combustion in Gas Turbines." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9723.
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Current improvements in gas turbine engine performance have arisen primarily due to increases in turbine inlet temperature and compressor pressure ratios. However, a maximum possible turbine inlet temperature exits in the form of the adiabatic combustion temperature of the fuel. In addition, thermal limits of turbine blade materials also places an upper bound on turbine inlet temperatures. Thus, the current strategy for improving gas turbine efficiency is inherently limited. Introduction of a new gas turbine, based on an alternative work cycle utilizing isothermal combustion (i.e. combustion within the turbine) affords significant opportunities for improving engine output and/or efficiency. However, implementation of such a scheme presents a number of technological challenges such as holding a flame in high-speed flow. The current research is aimed at determining whether such a combustion scheme is feasible using computational methods. The geometry, a simple 2-D cascade utilizes surface injection within the stator or rotor boundary layers (including the rotor pressure side recirculation zone (a natural flame holder).
Computational methods utilized both steady and time accurate calculations with transitional flow as well as laminar and turbulent combustion and species transport. It has been determined that burning within a turbine is possible given a variety of injection schemes using "typical" foil geometries under "typical" operating conditions. Specifically, results indicate that combustion is self-igniting and, hence, self-sustaining given the high temperatures and pressures within a high pressure turbine passage. Deterioration of aerodynamic performance is not pronounced regardless of injection scheme. However, increased thermal loading in the form of higher adiabatic surface temperatures or heat transfer is significant given the injection and burning of the fuel within the boundary layer. This increase in thermal loading is, however, minimized when injection takes place in or near a recirculation zone. The effect of injection location on pattern factors indicates that suction side injection minimizes temperature variation downstream of the injection surface (for rotor injection only). In addition, the most uniform temperature profile (in the flow direction) is achieved by injection fuel and combustion nearest to the source of work extraction. Namely, injection at the rotor produces the most "isothermal" temperature distribution. Finally, a pseudo direct simulation of an isothermal machine is conducted by combining simulation data and assumed processes. The results indicate that isothermal combustion results in an increase in turbine specific work and efficiency over the equivalent Brayton cycle.Master of Science
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Manners, A. P. "The calculation of the flows in gas turbine combustion systems." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/8397.
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Manners, A. P. "The calculation of the flows in gas turbine combustion systems." Online version, 1988. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.366981.
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Honegger, Ueli. "Gas turbine combustion modeling for a Parametric Emissions Monitoring System." Thesis, Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/371.
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