Dissertations / Theses on the topic 'High pressure spray combustion'

La simulation des écoulements diphasiques rencontrés dans les moteurs à combustion interne (MCI) est de grande importance pour la prédiction de la performance des moteurs et des émissions polluantes. L’injection directe du carburant liquide à l’intérieur de la chambre de combustion génère loin de l’injecteur un brouillard de gouttes polydisperses, communément appelé spray. Du point de vue de la modélisation, l’émergence des méthodes Eulériennes pour la description du spray est considérée prometteuse par la communauté scientifique. De plus, la prise en compte de la distribution en taille des gouttes par les approches Eulériennes, de manière peu coûteuse en temps de calcul, n’est plus considérée comme un verrou depuis le développement de la méthode Eulerian Multi Size Moment (EMSM). Afin d’envisager la simulation de configurations réalistes de MCI, ce travail de thèse propose de modéliser les interactions turbulentes two-way entre le spray polydisperse évaporant et la phase gazeuse environnante par la méthode EMSM. Dans le contexte du formalisme Arbitrary Lagrangian Eulerian (ALE) dédiée au traitement du maillage mobile, les termes sources présents dans le modèle diphasique sont traités séparément des autres contributions. Le système d’équations est fermé à l’aide d’une technique de reconstruction par maximisation d’entropie (ME), originellement introduite pour EMSM. Une nouvelle stratégie de résolution a été développée pour garantir la stabilité numérique aux échelles de temps très rapides introduites par les transferts de masse, quantité de mouvement et énergie, tout en respectant la condition de réalisabilité associée à la préservation de l’espace des moments d’ordre ´élevé. A l’aide des simulations académiques, la stabilité et la précision de la méthode ont été étudiées aussi bien pour des lois d’évaporation constantes que dépendantes du temps. Tous ces développements ont été intégrés dans le code industriel IFP-C3D dédié aux écoulements compressibles et réactifs. Dans le contexte de la simulation en 2-D de l’injection directe, les résultats se sont avérés très encourageants comme en témoignent les comparaisons qualitatives et quantitatives de la méthode Eulerienne à la simulation Lagrangienne de référence des gouttes. De plus, les simulations en 3-D effectuées dans une configuration typique de chambre de combustion et des conditions d’injection réalistes ont donné lieu à des résultats qualitativement très satisfaisants. Afin de prendre en compte la modélisation de la turbulence, une extension moyennée, au sens de Reynolds, des équations du modèle diphasique two-way est dérivée, un soin particulier étant apporté aux fermetures des corrélations turbulentes. La répartition de l’énergie dans le spray ainsi que les interactions turbulentes entre les phases ont été étudiées dans des cas tests homogènes. Ces derniers donnent un aperçu intéressant sur la physique sous-jacente dans les MCI. Cette nouvelle approche RANS diphasique est maintenant prête à être employée pour les simulations d’application de MCI
The ability to simulate two-phase flows is of crucial importance for the prediction of internal combustion engine (ICE) performance and pollutant emissions. The direct injection of the liquid fuel inside the combustion chamber generates a cloud of polydisperse droplets, called spray, far downstream of the injector. From the modeling point of view, the emergence of Eulerian techniques for the spray description is considered promising by the scientific community. Moreover, the bottleneck issue for Eulerian methods of capturing the droplet size distribution with a reasonable computational cost, has been successfully tackled through the development of Eulerian Multi Size Moment (EMSM) method. Towards realistic ICE applications, the present PhD work addresses the modeling of two-way turbulent interactions between the polydisperse spray and its surrounding gas-phase through EMSM method. Following to the moving mesh formalism ArbitraryLagrangian Eulerian (ALE), the source terms arising in the two-phase model have been treated separately from other contributions. The equation system is closed through the maximum entropy (ME) reconstruction technique originally introduced for EMSM. A new resolution strategy is developed in order to guarantee the numerical stability under veryfast time scales related to mass, momentum and energy transfers, while preserving the realizability condition associated to the set of high order moments. From the academic point of view, both the accuracy and the stability have been deeply investigated under both constant and time dependent evaporation laws. All these developments have beenintegrated in the industrial software IFP-C3D dedicated to compressible reactive flows. In the context of 2-D injection simulations, very encouraging quantitative and qualitative results have been obtained as compared to the reference Lagrangian simulation of droplets. Moreover, simulations conducted under a typical 3-D configuration of a combustion chamber and realistic injection conditions have given rise to fruitful achievements. Within the framework of industrial turbulence modeling, a Reynolds averaged (RA) extension of the two-way coupling equations is derived, providing appropriate closures for turbulent correlations. The correct energy partitions inside the spray and turbulent interactions between phases have been demonstrated through homogeneous test-cases. The latter cases gave also some significant insights on underlying physics in ICE. This new RA approach is now ready for ICE application simulations

Afin de réduire la consommation spécifique et les émissions de CO₂ des moteurs aéronautiques, les industriels cherchent à augmenter la pression maximale dans le cycle thermodynamique de Brayton. Cette augmentation de pression entraîne un fort impact sur la structure de la flamme (épaisseur, vitesse, cinétique chimique) mais également sur les émissions de polluants, tels que les NOx. Les émissions de NOx peuvent être limitées en adoptant des technologies innovantes comme les chambres de combustion low-NOx. De même, la haute pression dans la chambre impacte également les propriétés radiatives des gaz brûlés, qui sont importantes pour les diagnostics optiques utilisés pour caractériser la flamme. Un nouveau système d’injection de type pauvre prémélangé (LP pour Lean-Premixed) pour brûleurs aéronautiques a été étudié expérimentalement au laboratoire CORIA à Rouen avec des diagnostics optiques avancés. Dans le cadre de ces travaux, des simulations aux grandes échelles de ce système ont été réalisées pour un point de fonctionnement de référence à 8.33bar et 669.3K. L’impact des caractéristiques de l’atomisation sur la flamme est évalué par une étude paramétrique. Une analyse du temps d’évaporation caractéristique et de son influence sur la flamme a été effectuée. Cette étude paramétrique montre que la qualité de l’atomisation influence fortement la topologie de la flamme et la distribution du combustible dans la chambre de combustion. Les résultats numériques sont ensuite comparés aux données expérimentales afin d’apporter des précisions sur la topologie de la flamme. De plus, un modèle à deux niveaux capable de simuler la Fluorescence Induite par Laser (LIF) a été développé. Le but de ce modèle est de pouvoir comparer des images brutes obtenues expérimentalement avec les résultats numériques. À cet effet, l’interaction faisceau laser / gaz brûlés est modélisée pour quantifier les phénomènes d’absorption et de “quenching”, qui sont importants pour obtenir des mesures quantitatives à partir du signal de fluorescence. Avec ce modèle, les simulations permettent d’évaluer les propriétés radiatives des gaz brûlés le long du parcours de la nappe laser
To reduce the specific consumption and CO2 emissions of aircraft engines, manufacturers are seeking to increase the maximum pressure in Brayton’s thermodynamic cycle. This pressure increase has a strong impact on the flame structure (thickness, speed, chemical kinetics) but also on pollutant emissions. High pressure leads to an increase in NOx emissions, which can be reduced by the adoption of low-NOx technologies. It also impacts the radiative properties of the burnt gases. These burnt gases are important since they are used in optical diagnostics to characterize the flame. A new Lean-Premixed (LP) injection system for aeronautical burners was experimentally investigated with advanced optical diagnostics at CORIA laboratory in Rouen. This work aims to perform Large-Eddy Simulations of this injector at a reference operating point at 8.33 bar and669.3K. The spray features impact on the flame is assessed by a specific parametric study. An analysis of the characteristic evaporation time and its influence on the flame is carried out. This parametric study shows that the quality of atomization strongly influences the flame topology and fuel distribution in the combustion chamber. The numerical results are then compared with the experimental data. In addition, a two-level model capable of simulating Laser Induced Fluorescence (LIF) has been developed. The purpose of this model is to be able to compare raw images obtained experimentally with numerical results. To this purpose, the interaction between the laser sheet and the burnt gases is modeled to quantify the absorption and quenching phenomena, which are important to obtain quantitative measurements from a fluorescence signal. With this model, simulations are used to evaluate the radiative properties of the burnt gases along the laser sheet path

[EN] The potential of diesel engines in terms of robustness, efficiency and energy density has made them widely used as power generators and propulsion systems. Specifically, fuel atomization, vaporization and air-fuel mixing, have a fundamental effect on the combustion process, and consequently, a direct impact on pollutant formation, fuel consumption and noise emission. Since the combustion chamber has a limited space respect to the spray penetration, wall impingement is considered to be a common event in direct injection diesel engines, having a relevant influence in the spray evolution and its interaction with both surrounding air and solid walls. This makes of spray-wall interaction an important factor for the combustion process that is still hardly understood. At cold-start conditions, the low in-chamber pressures and temperatures promote the deposition of fuel in the piston wall, which leads to a boost in the formation of unburned hydrocarbons. Additionally, modern design trends such as the increment of rail pressures in injection systems and the progressive reduction of the engine displacement, favor the emergence of spray collision onto the walls. In spite of the evident relevance of the comprehension of this phenomenon and the efforts of engine researchers to reach it, the transient nature of injection process, its small time scales and the complexity of the physical phenomena that take place in the vicinity of the wall, make challenging the direct observation of this spray-wall interaction. Even though computational tools have proven to be priceless in this field of study, the need for reliable experimental data for the development of those predictive models is present. This thesis is aimed to shed light on the fundamental characteristics of spray-wall interaction (SWI) at diesel-like chamber conditions. A flat wall was set at different impingement distances and angles respect to the spray. In this way, two different kinds of experimental investigations on colliding sprays were carried out: A transparent quartz wall was employed into the chamber to, in isolation, analyze the macroscopic characteristics of the spray at both evaporative inert and reactive conditions, which have been observed laterally and through the wall, thanks to the use of a high-pressure and high-temperature vessel with optical accesses. This same test rig was used in the second kind of experiments, where instead of the quartz plate, a stainless steel wall was used to capture the effect of the operating conditions on the heat flux between the wall and the spray during the injection-combustion events and to determine how spray and flame evolution are affected by realistic heat transfer situations. This wall was instrumented to control its initial in-chamber surface temperature and to measure its variation with time by using high-speed thermocouples. Tests at free-jet conditions were also performed in order to provide a solid comparative base for those experiments.
[ES] El potencial de los motores diesel en términos de robustez, eficiencia y la densidad de energía los ha hecho ser ampliamente usados como generadores de energía y sistemas propulsivos. Específicamente, la atomización de combustible, vaporización y mezcla de aire y combustible tienen un efecto fundamental en el proceso de combustión y, en consecuencia, un impacto directo en la formación de emisiones contaminantes, consumo de combustible y generación de ruido. Dado que la cámara de combustión tiene un espacio limitado con respecto la capacidad de penetración del chorro, el impacto de la pared se considera bastante común en motores de inyección directa diésel, que tienen una influencia relevante en la evolución del chorro y su interacción con el aire circundante y las paredes sólidas. Esto hace de interacción chorro-pared, un factor importante para el proceso de combustión que aún es dificilmente comprendido. En condiciones de arranque en frío, las bajas presiones y temperaturas en la cámara promueven la deposición de combustible en la pared del pistón, lo que conduce a un aumento en los niveles de formación de hidrocarburos no quemados. Además, las tendencias modernas de diseño como el incremento de las presiones de rail en los sistemas de inyección y la progresiva reducción en la cilindrada de los motores, favorecen la aparición de colisiones entre chorro y pared. A pesar de la evidente importancia en la comprensión de este fenómeno y los esfuerzos de los investigadores para alcanzarla, la transitoria naturaleza del proceso de inyección, sus pequeñas escalas de temporales y la complejidad de los fenómenos físicos que tienen lugar en las proximidades de la pared, hacen que la observación directa de esta interacción chorro-pared sea un desafío. Aunque las herramientas computacionales han demostrado ser invaluables en este campo de estudio, la necesidad de datos experimentales confiables para el desarrollo de esos modelos predictivos está muy presente. Esta tesis tiene como objetivo arrojar luz sobre las características fundamentales de la interacción chorro-pared (SWI por sus siglas en inglés) en condiciones de cámara similares a las de un motor diesel. Se colocó una pared plana a diferentes distancias de impacto y ángulos con respecto al jet. De esta manera, dos tipos diferentes de investigaciones experimentales sobre chorros en colisión se llevaron a cabo: se empleó una pared de cuarzo transparente en la cámara para, de forma aislada, analizar las características macroscópicas del chorro en condiciones evaporativas inertes y reactivas, que pueden observarse lateralmente y a través de la pared, gracias al uso de una instalación de alta presión y alta temperatura ópticamente accesible. Esta misma instalación se utilizó en el segundo tipo de experimentos en los que se introdujo una pared de acero inoxidable para capturar adicionalmente el efecto de las condiciones de operación en el flujo de calor entre ésta y el chorro durante los eventos de inyección y combustión y para determinar cómo la evolución del chorro y la llama son afectadas por una situación realista de transferencia de calor. Esta pared fue instrumentada para controlar la temperatura inicial de su superficie expuesta a la cámara y medir su variación con el tiempo, utilizando termopares de alta velocidad. Ensayos en condiciones de chorro libre también se realizaron para proporcionar una base comparativa sólida para esos experimentos.
[CA] El potencial dels motors dièsel en termes de robustesa, eficiència i la densitat d'energia els ha fet ser àmpliament usats com a generadors d'energia i sistemes propulsius. Específicament, l'atomització de combustible, vaporització i barreja d'aire i combustible tenen un efecte fonamental en el procés de combustió i, en conseqüència, un impacte directe en la formació d'emissions contaminants, consum de combustible i generació de soroll. Atès que la cambra de combustió té un espai limitat pel que fa la capacitat de penetració de l'raig, l'impacte de la paret es considera bastant comú en motors d'injecció directa dièsel, que tenen una influència rellevant en l'evolució del doll i la seva interacció amb el aire circumdant i les parets sòlides. Això fa d'interacció doll-paret, un factor important per al procés de combustió que encara és difícilment comprès. En condicions d'arrencada en fred, les baixes pressions i temperatures a la cambra promouen la deposició de combustible a la paret del pistó, el que condueix a un augment en els nivells de formació d'hidrocarburs no cremats. A més, les tendències modernes de disseny com l'increment de les pressions de rail en els sistemes d'injecció i la progressiva reducció en la cilindrada dels motors, afavoreixen l'aparició de col·lisions entre el doll i la paret. Tot i l'evident importància en la comprensió d'aquest fenomen i els esforços dels investigadors per aconseguir-la, la transitòria naturalesa de l'procés d'injecció, les seves petites escales de temporals i la complexitat dels fenòmens físics que tenen lloc en les proximitats de la paret , fan que l'observació directa d'aquesta interacció doll-paret siga un desafiament. Tot i que les eines computacionals han demostrat ser invaluables en aquest camp d'estudi, la necessitat de dades experimentals fiables per al desenvolupament d'aquests models predictius està molt present. Aquesta tesi té com a objectiu donar llum sobre les característiques fonamentals de la interacció doll-paret (SWI per les seues sigles en anglès) en condicions de cambra similars a les d'un motor dièsel. Es va col·locar una paret plana a diferents distàncies d'impacte i angles pel que fa al jet. D'aquesta manera, dos tipus diferents d'investigacions experimentals sobre dolls en col·lisió es van dur a terme: es va emprar una paret de quars transparent a la cambra per, de forma aïllada, analitzar les característiques macroscòpiques del doll en condicions evaporació inerts i reactives, que poden observar lateralment i a través de la paret, gràcies a l'ús d'una instal·lació d'alta pressió i alta temperatura òpticament accessible. Aquesta mateixa instal·lació es va utilitzar en el segon tipus d'experiments en els quals es va introduir una paret d'acer inoxidable per capturar addicionalment l'efecte de les condicions d'operació en el flux de calor entre aquesta i el dull durant els esdeveniments d'injecció i combustió i per determinar com l'evolució del doll i la flama són afectades per una situació realista de transferència de calor. Aquesta paret va ser instrumentada per controlar la temperatura inicial de la seua superfície exposada a la càmera i mesurar la seua variació amb el temps, utilitzant termoparells d'alta velocitat. Assajos en condicions de doll lliure també es van realitzar per proporcionar una base comparativa sòlida per a aquests experiments.
Peraza Ávila, JE. (2020). Experimental study of the diesel spray behavior during the jet-wall interaction at high pressure and high temperature conditions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149389
TESIS

La préoccupation de plus en plus importante ces dernières décennies, liée à l’épuisement des ressources pétrolières et au réchauffement climatique par les gaz à effet de serre a accentué l’intérêt du butanol comme carburant alternatif dans le secteur des transports grâce à ses propriétés adaptées pour le moteur à allumage par compression. Cependant, le faible rendement des procédés de production et de séparation empêche encore sa commercialisation en tant que carburant. C’est pourquoi le mélange de fermentation intermédiaire de la production de butanol, Acétone-Butanol-Ethanol(ABE), est de plus en plus considéré comme un carburant alternatif potentiel en raison de ses propriétés similaires au butanol et de ses avantages quant à son cout énergétique pour sa fabrication.Dans ce cadre, ce travail a pour objectif d’étudier l’impact des propriétés de différents mélanges d’ABE et n-dodécane en comparaison avec des mélanges d’alcools (éthanol et butanol) sur le processus de pulvérisation et de combustion et ce,pour différentes proportions en volume allant de 20% à 50%. Pour cela, une nouvelle chambre de combustion appelée"New One Shot Engine ", a été réalisée et utilisée car les conditions haute pression et haute température de "Spray-A" (60bars, 800-900 K et 22,8 kg/m³) définies par le réseau Engine Combustion network (ECN) peuvent être atteintes. Autant les phases liquides et vapeur que de combustion ont été caractérisées grâce à l’utilisation des plusieurs techniques optiques (extinction, Schlieren, chimiluminescence d’OH*) dans des conditions non réactives (Azote pur) et réactives (avec15% d'oxygène). Ces résultats expérimentaux ont non seulement permis d’étudier l’impact en oxygène moléculaire et de fournir une nouvelle base de données fiables, mais aussi d’affirmer la possibilité d’utiliser jusque 20% d’ABE en volume dans des moteurs à allumage par compression, grâce à ses caractéristiques de pulvérisation et de combustion similaires au carburant Diesel conventionnel
The growing concern in recent decades, linked to the depletion of oil resources and global warming by greenhouse gases has increased the interest of butanol as an alternative fuel in the transport sector. However, the low yield of production and separation processes still prevents its commercialization as a fuel. Therefore, the intermediate fermentation mixture of butanol production, Acetone-Butanol-Ethanol (ABE), is increasingly considered as a potential alternative fuel because of its similar properties to butanol and its advantages in terms of the energy and cost in the separation process.The context of this work aims to study the impact of fuel properties on the spray and combustion processes of ABE mixture and alcohol fuels, blended with the diesel surrogate fuel, n-dodecane, in different volume ratio from 20% to 50%. A new combustion chamber called "New One Shot Engine," was designed and developed to reach the high-pressure and high temperatureconditions of "Spray-A" (60 bar, 800-900 K and 22.8 kg/m³) defined by the Engine Combustion Network (ECN).The macroscopic spray and combustion parameters were characterized by using the several optical techniques (extinction,Schlieren, chemiluminescence of OH*) under non-reactive (pure Nitrogen) and reactive (15% of oxygen) conditions. These experimental results not only made it possible to study the molecular oxygen impact and provide a new accurate database,but also to affirm the possibility of using ABE up to 20% by volume in compression-ignition engines, as its spray and combustion characteristics similar to conventional diesel fuel

Les motoristes aéronautiques misent sur le développement de systèmes d’injection de carburant innovants pour réduire la consommation de carburant et les émissions de polluants. L’objectif de la thèse est de contribuer à l’étude expérimentale d’un injecteur « Lean Premixed » par le développement de diagnostics lasers couplant des approches basées sur la diffusion de Mie et l’émission fluorescente de traceurs. Les mesures ont été réalisées sur le banc de combustion haute pression HERON. Une approche novatrice avec l’imagerie de fluorescence du kérosène a permis d’obtenir une quantification du mélange kérosène/air. La structure de flamme a été mesurée simultanément par PLIF-OH et des mesures PIV de vitesse ont complété cette analyse. Un développement préliminaire de la PLIF-CO a également été mené. Les nombreuses mesures permettent de fournir une analyse détaillée des interactions flamme/spray/aérodynamique lors d’une combustion swirlée stabilisée kérosène/air à haute pression
Aeronautical engine manufacturers are banking on the development of innovative fuel injection systems to reduce fuel consumption and pollutant emissions. The aim of the thesis is to contribute to the experimental investigation of a "Lean Premixed" injector by developing laser diagnostics coupling approaches based on Mie scattering and fluorescent emission of tracers. Measurements are performed at high pressure on the HERON combustion test bench. An innovative approach with fluorescence imaging of kerosene has resulted in the quantification of the kerosene/air mixture. The flame structure was analyzed simultaneously by OH-PLIF and velocity PIV measurements were performed to complete this analysis. A preliminary development of CO-PLIF was also conducted. The numerous measurements provided a detailed analysis of the mechanisms of flame/spray/aerodynamic interactions during a swirl-stabilized kerosene/air combustion at high pressure

The object of this work is to apply CFD simulation in the description of the spray burning. As a case study, a pressure swirl injector, characterized and tested by NIST, has been chosen, which atomize liquid kerosene in an atmosphere of gaseous oxygen. The chamber dimensions allow a complete evaporation, avoiding the impact of drops on the circular wall. Swirl-axisymmetric domain and steady state permit to include combustion, a complex process, without requiring of high computational resources. Continuous phase is treated with an Eulerian reference, while fuel drops are tracked following the Lagrangian formulation. Chemical kinetics is reduced to the concept of mixture fraction. This assumption avoids the solution of too many transport equations for all involved species. In the first simulation, the inlet boundary of the continuous phase is obtained from the numerical solution of a fully developed flow transporting the oxidant gas. Then, four cases are proposed and solved, changing the turbulence intensity and swirl velocity on the inlet boundary, each parameter with two different values. Finally, results for the axial velocity, streamlines, drops trajectories, temperature, distribution and total production of selected species are analyzed and compared with other related studies.

La combustion diphasique implique de nombreux phénomènes physiques complexes, comprenant l'atomisation, la dispersion, l'évaporation et la combustion. Bien que la simulation numérique soit un outil performant pour aborder ces différentes interactions entre les phases liquides et gazeuses, la méthode doit être validée par des études expérimentales fiables. Par conséquent, des données expérimentales précises sur la structure de la flamme et sur les propriétés de la phase liquide et gazeuse le long des étapes d'évaporation et de combustion sont nécessaires. La complexité des configurations aéronautiques réelles implique d'étudier l'effet des propriétés locales sur la dynamique des flammes pour une configuration canonique. Ce travail, réalisé dans le cadre du projet ANR TIMBER, a pour objectif d'améliorer la compréhension de la combustion en flux diphasique, ainsi que de produire une base de données efficace et originale pour la validation des modèles utilisés dans les LES
Liquid fuels are the primary energy source in a wide range of applications including industrial and residential furnaces, internal combustion engines and propulsion systems. Pollutant emission reduction is currently one of the major constraints for the design of the next generation combustion chamber. Spray combustion involves many complex physical phenomena including atomization, dispersion, evaporation and combustion, which generally take place simultaneously or within very small regions in the combustion chambers. Although numerical simulation is a valuable tool to tackle these different interactions between liquid and gas phases, the method needs to be validated through reliable experimental studies. Therefore, accurate experimental data on flame structure and on liquid and gas properties along the evaporation and combustion steps are needed and are still challenging. A joint effort between numerical and experimental teams is necessary to meet tomorrow's energy challenges and opportunities. The complexity of the real aeronautical configurations implies to study the effect of local properties in flame dynamics on a canonical configuration, which presents the essential feature of very well defined boundary conditions. This work, carried out within the framework of the ANR TIMBER project, aims to improve the understanding of two-phase flow combustion, as well as to produce an efficient and original database for the validation of the models used in LES

The objective of this work was to extend the range of turbulent burning velocities presented in the literature by performing new measurements at elevated pressures over a range of turbulent velocities, u' (r. m. s. deviation from the mean velocity). The influence of equivalence ratio was investigated for a fixed u'= 2 m/s at 0.5 MPa for methane, a 70 % methane/ 30 % hydrogen mixture, methanol, isooctane and a gasoline (Shell dutch-pura). The mixtures were varied from the lean ignition limit to rich limit up to a maximum equivalence ratio of 2. Further measurements were performed with iso-octane and the effect of r. m. s. turbulent velocity (u' = 0.5,1,2,4,6 m/s), pressure (P = 0.1,0.5,1 MPa) and equivalence ratio (0= 0.8,1.0,1.2 and 1.4) were investigated, to produce a database. Turbulent flames were centrally ignited in isotropic turbulence in the Leeds fan stirred bomb. Flame progress was monitored using high-speed schlieren photography and pressure measurements. The turbulent burning velocity based on the production of burned mass, ur was obtained from both techniques. The burning velocities obtained from schlieren imaging and pressure measurements were in good agreement. The turbulent flames continually accelerated throughout the time that they were monitored. This was the result of turbulent flame development, with the range of turbulent scales wrinkling the flame surface increasing as the flames grew. It was shown that flame development occurred primarily as a result of the kernel radius, rather than the time from ignition. For each turbulent condition, corresponding spherically expanding laminar flames were ignited and imaged with schlieren photography. The measurements were processed to give the stretch free laminar burning velocity and also the Markstein number, a measure of the influence of stretch on the burning velocity. The peak laminar burning velocity was found to be in the range 1>ø>1.2 depending on the fuel. At 0.5 MPa a number of the flames were observed to become cellular, in some cases this occurred from ignition, this has been linked to negative Markstein numbers which were observed with lean methane and rich iso-octane - air mixtures. The peak in the turbulent burning velocity with equivalence ratio varied considerably with the different fuels, and did not correspond to that for the laminar burning velocity. In the case of methane and the 70 % methane/ 30 % hydrogen mixture the peak turbulent burning velocity was lean of stoichiometric. In contrast, for iso-octane and the gasoline, the peak in %, was beyond 0=1.3. It was concluded that the shift in the peak could be explained by comparison with the measured Markstein numbers. In the iso-octane database, pressure was not observed to have a significant influence on the turbulent burning velocity for some conditions, however, when fuel rich higher pressure gave an increase in utr. Turndown of utr, (the burning velocity does not increase as with the turbulent velocity) was observed at high turbulence velocities, although this depended on the equivalence ratio. The measurements were then compared with existing turbulent burning velocity expressions and correlations. In general these expressions were found not to predict the effect of equivalence ratio well.

The thesis reports experimental and theoretical studies of premixed combustion rates at high pressure and temperature. It focuses on measurements of laminar and turbulent burning velocities at high pressures and temperatures approaching those in engines, with emphasis on flame instabilities. To encourage the development of such instabilities, mixtures with negative Markstein numbers were employed. Three different methods were used to measure burning velocities in a spherical bomb. The bomb was fitted with windows for observing flame propagation at the centre of the bomb and a transducer to measure pressure. Four fans at the wall of the bomb were employed for mixing and the generation of turbulence. The first two methods of measuring burning velocities were well established and involved central ignition. The third method was new and involved implosions of two flame kernels that originated at spark plugs mounted near the wall. It enabled the later stages of burning at the high pressures to be observed and burning velocities to be measured. The first method depended on highspeed schlieren photographic measurements of the flame speed, dr / dt , at different radii,r, supplemented by pressure measurements. The second method was employed when the flame front has propagated beyond the boundaries of the window and could no longer be observed. The expression for the burning velocity rested upon the assumption that the flame was spherical and the fractional pressure rise was equal to the fractional mass burned. Two different approaches were employed for the new third method, one was based on geometrical considerations, the other on the fractional pressure rise. A knowledge of the flame area and the appropriate geometrical analysis enabled two expressions to be obtained for the burning velocity. The agreement between the two different approaches for obtaining burning velocities, and the general consistency of the results for both initially laminar and turbulent flames, showed the technique to be accurate and suitable for obtaining burning velocities at high pressure. As a result, burning velocities, initially laminar, were measured for iso-octane - air at equivalence ratios ranging from 0.8 to 1.6 at initial pressures of 0.5 and 1.0 MPa. They were also measured for hydrogen - air mixtures at equivalence ratios of 0.3 to 0.5. Modification of the linear theory of flame instability of Bechtold and Matalon enabled the laminar burning velocity to be obtained from the values of unstable burning velocities. Enhancements of the laminar burning velocity of up to six fold were measured. Turbulent burning velocities were measured over a range of rms turbulent velocities ranging from 0.25 to 3 mls. It was found that these values of burning velocity were higher than those predicted from earlier expressions, derived predominantly from more stable flames close to atmospheric pressure. The possibility that turbulent burning velocities might be enhanced, not only by the effect of flame stretch at negative Markstein numbers, but also by flamelet instabilities was also investigated at high pressures and with mixtures with very low Markstein numbers. Stoichiometric and rich iso-octane-air flames were selected for this study and mixtures were ignited at initial pressures of 0.5 and 1.0 MPa. This enabled burning velocities to be measured up to 6 MPa.

This work is devoted to generate knowledge and high quality experimental data of catalytic combustion at operational gas turbine conditions. The initial task of the thesis work was to design and construct a high pressure combustion test facility, where the catalytic combustion experiments can be performed at real gas turbine conditions. With this in mind, a highly advanced combustion test facility has been designed, constructed and tested. This test facility is capable of simulating combustion conditions relevant to a wide range of operating gas turbine conditions and different kinds of fuel gases. The shape of the combustor (test section) is similar to a “can” type gas turbine combustor, but with significant differences in its type of operation. The test combustor is expected to operate at near adiabatic combustion conditions and there will be no additions of cooling, dilution or secondary supply of air into the combustion process. The geometry of the combustor consists of three main zones such as air/fuel mixing zone, catalytic reaction zone and downstream gas phase reaction zone with no difference of the mass flow at inlet and exit. The maximum capacity of the test facility is 100 kW (fuel power) and the maximum air flow rate is 100g/s. The significant features of the test facility are counted as its operational pressure range (1 – 35 atm), air inlet temperatures (100 – 650 °C), fuel flexibility (LHV 4 - 40 MJ/m3) and air humidity (0 – 30% kg/kg of air). Given these features, combustion could be performed at any desired pressure up to 35 bars while controlling other parameters independently. Fuel flexibility of the applications was also taken into consideration in the design phase and proper measures have been taken in order to utilize two types of targeted fuels, methane and gasified biomass. Experimental results presented in this thesis are the operational performances of highly active precious metal catalysts (also called as ignition catalysts) and combinations of precious metal, perovskites and hexaaluminate catalysts (also called as fully catalytic configuration). Experiments were performed on different catalytic combustor configurations of various types of catalysts with methane and simulated gasified biomass over the full range of pressure. The types of catalysts considered on the combustor configurations are palladium on alumina (Pd/AL2O3), palladium lanthanum hexaaluminate (PdLaAl11O19), platinum on alumina (Pt/AL2O3),and palladium:platinum bi-metal on alumina (Pd:Pt/AL2O3). The influence of pressure, inlet temperature, flow velocity and air fuel ratio on the ignition, combustion stability and emission generation on the catalytic system were investigated and presented. Combustion catalysts were developed and provided mainly by the project partner, the Division of Chemical Technology, KTH. Division of Chemical Reaction Technology, KTH and Istituto di Ricerche sulla Combustione (CNR) Italy were also collaborated with some of the experimental investigations by providing specific types of catalysts developed by them for the specific conditions of gas turbine requirements.

QC 20131125

High-intensity pyrolysis, rapid heating in an inert gas atmosphere at up to 20 atm pressure, of 6 Australian coals was examined to gain further insight into high-intensity processes such as Integrated Gasification Combined Cycles (IGCC). Experiments focussed on pyrolysis in a specially developed Wire Mesh Reactor (WMR). The particle temperature lagged that of the mesh by 0.2 seconds at a heating rate of 100??~C s -1 and was predicted by modelling. This is part of the reason the volatile yield (VY) results for 10 s hold-time at ???b1.7 wt% daf of coal, is much more reproducible than 1 s hold-time experiments at ???b4.2 wt% daf of coal. Four coals of the same rank did not behave identically when heated. Three of the coals had a pyrolysis VY the same as the proximate VM when heated to 100??~C at 1 atm but the fourth, higher inertinite coal had a 1 atm pyrolysis VY 90% of its proximate VM. All four coals of similar rank had a significant decrease in VY, between 10 and 20 wt% daf of coal, with pressure increasing from 1 to 20 atm. The two lower rank coals showed less decrease in VY with increasing pressure than the higher rank and higher inertinite coals. The lower decrease in VY with increased pressure was mostly attributed to the lower inertinite levels for both the coals of similar rank and VM, and the coals of lower rank. Char characteristics examined focussed on pore Surface Area (SA). For high intensity WMR and Drop Tube Furnace (DTF) pyrolysis experiments CO2 SA for char from a particular coal was similar but the BET SA different. This was due to the char in the WMR experiments having longer to form larger pores determined by BET N2 SA. Both the N2 and CO2 SA was more than an order of magnitude greater than for low intensity pyrolysis char. This highlights that the WMR can be used to attain char with similar CO2 SA characteristics as other high intensity pyrolysis experiments and to provide a more meaningful insight into char reactivity than low intensity chars do.

For performance optimisation of modern liquid cryogenic bipropellant rocket combustion chambers, one component which plays an important role in reducing the wall side heat flux, is the behaviour of the cooling film. At the Institute of Space Propulsion of the German Aerospace Center (DLR) in Lampoldshausen, hot test runs have been performed using the experimental combustion chamber BKM, to investigate the wall side heat flux which is -- among other factors -- dependent on cooling film properties. To gain more insight into the film behaviour under real rocket-like conditions, optical diagnostics have been applied. The chosen methods were shadowgraphy and OH* imaging producing optical data sets which are analysed in this study. In this context, a description of the necessary background information is given, concerning rocket combustion chambers, film cooling and optical diagnostics of O2/H2 combustion. The applied methodology for optical analysis is described, followed by a presentation of the results. During the test campaign, it became clear that the optical setup was not optimised for creating meaningful shadowgraphy recordings which is why the shadowgraphy data has to be treated as flame emission imaging. The behaviour of the gas layer adjacent to the chamber wall could be characterised based on qualitative (luminosity, LOx shadow, reflection, recirculation zone and flame shape) and quantitative (layer thickness, layer length, pressure conditions) analysis. The thickness could be identified for each load step and an average length of the layer was found as well. OH* imaging has been used supplementary to support the observations from the flame emission images. An in depth frame by frame analysis was not possible due to time constraints. However, the time averaged images yielded results in accordance to the flame emission and could give a relative figure for the temperature distribution in the combustion volume. An artefact in the data was found, stemming presumably from the image intensifier. This artefact needs to be researched for a future error reduction in the data of this and other campaigns. Additionally, the thickness of the layer suggested a correlation to the models for film cooling efficiency. Such a correlation could not be established. Nevertheless, the film cooling models show the same behaviour as the data obtained from the flame emission imaging. Finally, suggestions are given how the data analysis and the optical setup could be improved for future, similar campaigns.

The main objective of this study was to investigate the factors that influence the oxidation rate of large (five to eight millimeters in diameter) coal and char particles. To accomplish this, experiments were performed in which the gas temperature, gas velocity, particle size, partial pressure of oxygen, and total pressure were varied. The experiments were performed with the cantilever balance attachment and the high pressure controlled profile reactor. Approximately 90 combustion experiments were performed with Pittsburgh, Utah Blind Canyon, and Wyodak-Anderson coal. These experiments were performed at atmospheric pressure with air and varied gas temperature, gas velocity, and particle size. Following the experiments performed with coal, approximately 70 experiments were performed with char made from Pittsburgh coal. These experiments varied all the environmental conditions mentioned above as well as partial pressure of oxygen and total pressure. After the experiments were completed, the data were analyzed and the following conclusions were made. An increase in the partial pressure of oxygen dramatically increased the oxidation rate when the total pressure remained constant. The oxidation rate was only slightly affected when the partial pressure of oxygen was raised by increasing the total pressure. The oxidation rate dramatically decreased when the partial pressure of oxygen was held constant and the total pressure was raised. The oxidation rate noticeably increased when the initial mass of the particle was decreased. The gas temperature and gas velocity did not affect the oxidation rate greatly for the experiments performed with coal. The oxidation rate increased for the experiments performed with char at the high gas temperature and high gas velocity conditions.

The main scope of this project was to determine if a plasma torch could operate on pure hydrocarbon feedstocks and, if so, to catalogue the torch operational characteristics. The future goal of the project is to design a plasma torch for supersonic combustion applications that operates off of the vehicle main fuel supply to simplify onboard fuel systems. Experiments were conducted with argon, methane, ethylene and propylene. Spectrographic tests and tests designed to catalogue current/voltage characteristics, plasma jet phenomena, arc stability dependencies, electrode erosion rate and torch body temperature were performed. Spectrographic analysis of the plasma jet exhaust confirmed the presence of combustion-enhancing radicals for each hydrocarbon gas tested. Also, it was discovered that simple hydrocarbon gases, such as methane, produced smooth torch operation, while even slightly more complex gases, ethylene and propylene, caused unsteady performance. Plasma jet oscillation was found to be related to the voltage waveform of the power supplies, indicating that plasma jet length and oscillation rate could be controlled by changing the input voltage. The plasma torch for this study was proven to have the capability of operating with pure hydrocarbon feedstocks and producing radicals that are known to reduce combustion reaction rate times. The torch was demonstrated to have potential for use in supersonic combustion applications.
Master of Science

Research, pilot scale and field developments of In-Situ Combustion (ISC) for enhanced oil recovery (EOR) in shallow, low pressure, heavy oil reservoirs intensified between the first and the second oil crisis from 1973 to 1981. A decline of interest in EOR followed the collapse of the oil prices in 1986. Renewed interest on in-situ combustion EOR research in the late 1980’s and beginning of the 1990’s was expanded and focused on high pressure medium and light oil reservoirs. The applicability of air injection in deep high pressure light petroleum reservoirs was established by research work of Greaves et al. in 1987 & 1988, Yannimaras et al. in 1991 and Ramey et a l in 1992. Accelerating rate calorimeter (ARC) tests were used to screen the applicability of various types of light oil reservoirs for in-situ combustion EOR by Yannimaras and Tiffin in 1994. The most successful light oil air injection project in the 1990s in the Medicine Pole Hills Unit, Williston Basin, N. Dakota started in 1987 and was reported by Kumar, Fassihi & Yannimaras, in 1994. Low temperature oxidation of light North Sea petroleum was studied at the University of Bath. A high-pressure combustion tube laboratory system was built at Bath University to evaluate performance of medium and light petroleum in-situ combustion processes. Gravity effects and the impact of horizontal wells in Forced Flow In-Situ Combustion Drainage Assisted by Gravity (FFISCDAG) were studied with three-dimensional combustion experiments. In this study, the university of Bath combustion tube experiments have been simulated and history matched. The tube experiments were up-scaled and field simulation studies were performed. A generic PVT characterization scheme based on 5 hydrocarbon pseudo-components was used, which was validated for light Australian and medium ‘Clair’ oil. A generic chemical reaction characterization scheme was used, which was validated for light Australian and medium ‘Clair’ oil. Advanced PVT and chemical reaction characterizations have been recommended for future work with more powerful hardware platforms. Extensive front track and flame extinction studies were performed to evaluate the performance of currently available non-iso-thermal simulators and to appraise their necessity in air injection processes. Comparative ISC field scale numerical simulation studies of Clair medium oil and light Australian petroleum were based on up-scaled combustion tube experimental results. These studies showed higher than expected hydrocarbon recovery in alternative EOR processes for both pre and post water flood implementation of ISC. Further in this study field scale numerical simulation studies revealed high incremental hydrocarbon recovery was possible by gravity assisted forced flow. The applicability of light oil ISC to gas condensate and sour petroleum reservoirs has been examined in this study with promising results. Light petroleum ISC implemented by a modified water flood including oxidants such as H2O2 and NH4NO3 are expected to widen the applicability of ISC processes in medium and light petroleum reservoirs, especially water flooded North Sea reservoirs.

The understanding and prediction of transient phenomena inside Liquid Rocket Engines (LREs) have been very difficult because of the many challenges posed by the conditions inside the combustion chamber. This is especially true for injectors involving liquid oxygen LOX and gaseous hydrogen GH₂. A wide range of length scales needs to be captured from high-pressure flame thicknesses of a few microns to the length of the chamber of the order of a meter. A wide range of time scales needs to be captured, again from the very small timescales involved in hydrogen chemistry to low-frequency longitudinal acoustics in the chamber. A wide range of densities needs to be captured, from the cryogenic liquid oxygen to the very hot and light combustion products. A wide range of flow speeds needs to be captured, from the incompressible liquid oxygen jet to the supersonic nozzle. Whether one desires to study these issues numerically or experimentally, they combine to make simulations and measurements very difficult whereas reliable and accurate data are required to understand the complex physics at stake. This thesis focuses on the numerical simulations of flows relevant to LRE applications using Large Eddy Simulations (LES). It identifies the required features to tackle such complex flows, implements and develops state-of-the-art solutions and apply them to a variety of increasingly difficult problems. More precisely, a multi-species real gas framework is developed inside a conservative, compressible solver that uses a state-of-the-art hybrid scheme to capture at the same time the large density gradients and the turbulent structures that can be found in a high-pressure liquid rocket engine. Particular care is applied to the implementation of the real gas framework with detailed derivations of thermodynamic properties, a modular implementation of select equations of state in the solver. and a new efficient iterative method. Several verification cases are performed to evaluate this implementation and the conservative properties of the solver. It is then validated against laboratory-scaled flows relevant to rocket engines, from a gas-gas reacting injector to a liquid-gas injector under non-reacting and reacting conditions. All the injectors considered contain a single shear coaxial element and the reacting cases only deal with H₂-O₂ systems. A gaseous oyxgen-gaseous hydrogen (GOX-GH₂) shear coaxial injector, typical of a staged combustion engine, is first investigated. Available experimental data is limited to the wall heat flux but extensive comparisons are conducted between three-dimensional and axisymmetric solutions generated by this solver as well as by other state-of-the-art solvers through a NASA validation campaign. It is found that the unsteady and three-dimensional character of LES is critical in capturing physical flow features, even on a relatively coarse grid and using a 7-step mechanism instead of a 21-step mechanism. The predictions of the wall heat flux, the only available data, are not very good and highlight the importance of grid resolution and near-wall models for LES. To perform more quantitative comparisons, a new experimental setup is investigated under both non-reacting and reacting conditions. The main difference with the previous setup, and in fact with most of the other laboratory rigs from the literature, is the presence of a strong co-flow to mimic the surrounding flow of other injecting elements. For the non-reacting case, agreement with the experimental high-speed visualization is very good, both qualitatively and quantitatively but for the reacting case, only poor agreement is obtained, with the numerical flame significantly shorter than the observed one. In both cases, the role of the co-flow and inlet conditions are investigated and highlighted. A validated LES solver should be able to go beyond some experimental constraints and help define the next direction of investigation. For the non-reacting case, a new scaling law is suggested after a review of the existing literature and a new numerical experiment agrees with the prediction of this scaling law. A slightly modified version of this non-reacting setup is also used to investigate and validate the Linear-Eddy Model (LEM), an advanced sub-grid closure model, in real gas flows for the first time. Finally, the structure of the trans-critical flame observed in the reacting case hints at the need for such more advanced turbulent combustion model for this class of flow.

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A high pressure and temperature combustion chamber was designed to compare the ignition properties of different fuels, including conventional F76 diesel and hydrotreated renewable diesel (HRD), derived from algae. Conditions were selected to capture the operating conditions within a large number of Navy systems, testing at a range of temperatures from 8001340 F and pressures as high as 20 atm. Three Navy-relevant injectors were procured for the testing as well as a commercial injector made by Sturman Industries. The Sturman diesel injector was characterized up to a fuel tip pressure of 9600 psi and produced Sauter Mean Diameters of approximately 90 microns, generally showing improved atomization for F-76 when compared to HRD at similar conditions. The combustion chamber utilized dynamic air injection with increased turbulence and the ability to alter the amounts of combustion products including CO, CO2 and H2O that typically exist in real engines from the previous combustion event. Qualification testing of the combustion chamber evaluated final pressures of up to 15 atmospheres and temperatures of 472 F, but revealed heat losses during the dynamic air injection events, resulting in temperatures below expected values and auto-ignition conditions for fuels under consideration. A fluidized bed heat exchanger will be implemented to supplement the existing design and reach the desired temperatures.

The goal of this thesis was to understand what parameters would be most impactful when delivering dry, pulverized coal in a dilute-phase, with a high-pressure feed-system to a pressurized oxy-combustion (POC) reactor. Many studies have conveyed materials in dense-phase plugs at high-pressure or in dilute-phase flows at atmospheric pressure. Very few studies have fluidized and conveyed materials in dilute-phase flows at high pressure, as we needed to. Additionally, studies which might have been applicable based upon system -pressure and -phase delivered findings that were empirically based and therefore not specifically applicable to non-similar systems. 220 different tests were ran using a bench-scale apparatus consisting of a hopper, connecting conveying pipes, and a filter point (representing the future reactor). The system was pressurized to 300 psi using CO2. Dry, pulverized coal with an average diameter of 50 microns and a bulk density of 800.9 kg/m3 was fluidized and conveyed with different combinations of fluidization inlet and fluidization outlet flowrates. Each specific flowrate combination was tested 3 to 5 times. The resulting coal flowrates were recorded and analyzed to see which flowrate combination delivered 13.6 kgs coal/hr and had the least variability between tests. The fluidization inlet and outlet flowrates, coal moisture content, and system geometry were key parameters. In a 2-inch diameter hopper the fluidization inlet flowrate should be kept at 0.119 m/s or below to keep the fluidization regime within the hopper below the transition point to the bubbling fluidization regime. This was beneficial since less CO2 was needed by the system and smaller perturbations within the bed didn't disrupt flow leaving the hopper. The fluidization outlet flowrate could still advance the fluidization regime within the hopper even if the fluidization inlet flowrate is kept at 0.119 m/s. For a ¼ inch diameter the outlet should be kept at 0.005 m/s or above. Additionally, the standard deviation in the measured coal flowrate decreased dramatically when flow of gas was allowed to exit through the top of the coal column (fluidization outlet). The standard deviation was 8.2 kg/hr with the fluidization outlet closed and 3.5 kg/hr with the fluidization outlet flowing to provide 0.005 m/s in the bed above the coal outlet. Coal should have a moisture content between 3% and 6% to ensure that electrostatic interactions between coal particles is kept to a minimum. Finally, these results were found for specific hopper and fluidization inlet and outlet diameters. If these diameters are changed then some calculation must be done for these results to be applicable to systems that are not like the one described later in this thesis.

This research work deals with the problem of the flame stabilization in the context of high pressure liquid rocket engines. Flame stabilization in a rocket engine is a critical feature. An instability can lead to important damages of the engine or the destruction of the launcher and the satellite. The engines (Vulcain 2 and Vinci) of the Ariane 5, and the future Ariane 6, use the hydrogen/oxygen propellants. One characteristic of this couple is its high specific impulse. The launcher performance is linked to the ratio of the payload to the total mass of propellants. For volume reasons the propellants are stored at low temperature of the order of a few tens of Kelvin. When injected in the combustion chamber, their combustion releases a huge amount of heat leading to temperature of 3500K. In order to predict the heat transfer between the flame, the solid injector and the cold propellants the Large Eddy Simulation, which allows to capture the unsteady features of the flow, is used in association with a thermal solver for the injector. This approach is validated with a low pressure experiment conducted at Centrale Paris, then a basic 1D configuration allows to understand the phenomena of high pressure flame-wall interaction. Finally a configuration representative of a coaxial rocket engine injector allows to evaluate the structure and the stabilization mechanisms of a cryogenic flame, the heat flux and the temperature of the injector.

Ignition and oxidation characteristics of CO/H2, H2/O2 and CO/H2/CH4/CO2/Ar fuel blends in air were studied using both experimental and computer simulation methods. Shock-tube experiments were conducted behind reflected shock waves at intermediate temperatures (825 < T < 1400 K) for a wide range of pressures (1 < P < 45 atm). Results of this study provide the first undiluted fuel-air ignition delay time experiments to cover such a wide range of syngas mixture compositions over the stated temperature range. Emission in the form of chemiluminescence from the hydroxyl radical (OH*) transition near 307 nm and the pressure behind the reflected shock wave were used to monitor reaction progress from which ignition delay times were determined. In addition to the experimental analysis, chemical kinetics calculations were completed to compare several chemical kinetics mechanisms to the new experimental results. Overall, the models were in good agreement with the shock-tube data, especially at higher temperatures and lower pressures, yet there were some differences between the models at higher pressures and the lowest temperatures, in some cases by as much as a factor of five. In order to discern additional information from the chemical kinetics mechanisms regarding their response to a wide range of experimental conditions, ignition delay time and reaction rate sensitivity analyses were completed at higher and lower temperatures and higher and lower pressures. These two sensitivity analyses allow for the identification of the key reactions responsible for ignition. The results of the sensitivity analysis indicate that the ignition-enhancing reaction H + O2 = O + OH and hydrogen oxidation kinetics in general were most important regardless of mixture composition, temperature or pressure. However, lower-temperature, higher-pressure ignition delay time results indicate additional influence from HO2- and CO- containing reactions, particularly the well-known H + O + M = HO2 + M reaction and also the CO + O + M = CO2 + M and CO + HO2 = CO2 + OH reactions. Differences in the rates of the CO-related reactions are shown to be the cause of some of the discrepancies amongst the various models at elevated pressures. However, the deviation between the models and the experimental data at the lowest temperatures could not be entirely explained by discrepancies in the current rates of the reactions contained within the mechanisms. Additional calculations were therefore performed to gain further understanding regarding the opposing ignition behavior for calculated and measured ignition delay time results. Impurities, friction induced ionization, static charge accumulation, boundary layer effects, wall reaction effects, and revised chemical kinetics were all considered to be possible mechanisms for the model and measured data disparity. For the case of wall-reaction effects, additional shock-tube experiments were conducted. For the remaining effects listed above, only detailed calculations were conducted. Results from this preliminary anomaly study are at this time inconclusive, but likely avenues for future study were identified. Additional kinetics calculations showed that the large difference between the experimental data and the chemical kinetics models predictions at low temperatures can be explained by at least one missing reaction relevant to low-temperature and high-pressure experimental conditions involving the formation of H2O2, although further study beyond the scope of this thesis is required to prove this hypothesis both theoretically and experimentally.
Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering PhD

The application of emission spectroscopy to monitor combustion products of solid rocket propellant combustion can potentially yield valuable data about reactions occurring within the volatile environment of a strand burner. This information can be applied in the solid rocket propellant industry. The current study details the implementation of a compact spectrometer and fiber optic cable to investigate the visible emission generated from three variations of solid propellants. The grating was blazed for a wavelength range from 200 to 800 nm, and the spectrometer system provides time resolutions on the order of 1 millisecond. One propellant formula contained a fine aluminum powder, acting as a fuel, mixed with ammonium perchlorate (AP), an oxidizer. The powders were held together with Hydroxyl-Terminated-Polybutadiene (HTPB), a hydrocarbon polymer that is solidified using a curative after all components are homogeneously mixed. The other two propellants did not contain aluminum, but rather relied on the HTPB as a fuel source. The propellants without aluminum differed in that one contained a bimodal mix of AP. Utilizing smaller particle sizes within solid propellants yields greater surface area contact between oxidizer and fuel, which ultimately promotes faster burning. Each propellant was combusted in a controlled, non-reactive environment at a range of pressures between 250 and 2000 psi. The data allow for accurate burning rate calculations as well as an opportunity to analyze the combustion region through the emission spectroscopy diagnostic. It is shown that the new diagnostic identifies the differences between the aluminized and non-aluminized propellants through the appearance of aluminum oxide emission bands. Anomalies during a burn are also verified through the optical emission spectral data collected.
M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering

Thesis (Ph.D.)--Aerospace Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Seitzman, Jerry; Committee Member: Jagoda, Jechiel; Committee Member: Lieuwen, Tim; Committee Member: Menon, Suresh; Committee Member: Tan, David.

An investigation was undertaken to determine the feasibility of increasing the hydrogen production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process (HyS). This investigation also involved the technical and economical analysis of the water gas shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical analysis of the water gas shift reaction was determined under the operating conditions selected on the basis of some information available in the literature. The high temperature system (HTS) and low temperature system (LTS) reactors were assumed to be operated at temperatures of 350ºC and 200ºC, respectively. The operating pressure for both reactors was assumed to be 30 atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was 242T/D, which is approximately two times the amount produced by the HyS process alone. The PSA was used for the purification process leading to a hydrogen product with a purity of 99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2 is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with CO2 and traces of CH4, CO, and saturated H2O. The estimated capital cost of the WGS plant with PSA is about US$50 million. The production cost is highly dependent on the cost of all of the required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2 based on the input cost of synthesis gas as produced by the POX process. In this case the production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg.
Thesis (M.Sc. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2006.

This work focuses on understanding the impact-initiated combustion of aluminum powder compacts. Aluminum is typically one of the components of intermetallic-forming structural energetic materials (SEMs), which have the desirable combination of rapid release of thermal energy and high yield strength. Aluminum powders of various sizes and different levels of mechanical pre-activation are investigated to determine their reactivity under uniaxial stress rod-on-anvil impact conditions, using a 7.62 mm gas gun. The compacts reveal light emission due to combustion upon impact at velocities greater than 170 m/s. Particle size and mechanical pre-activation influence the initiation of aluminum combustion reaction through particle-level processes such as localized friction, strain, and heating, as well as continuum-scale effects controlling the amount of energy required for compaction and deformation of the powder compact during uniaxial stress loading. Compacts composed of larger diameter aluminum particles (~70µm) are more sensitive to impact initiated combustion than those composed of smaller diameter particles. Additionally, mechanical pre-activation by high energy ball milling (HEBM) increases the propensity for reaction initiation. Direct imaging using high-speed framing and IR cameras reveals light emission and temperature rise during the compaction and deformation processes. Correlations of these images to meso-scale CTH simulations reveal that initiation of combustion reactions in aluminum powder compacts is closely tied to mesoscale processes, such as particle-particle interactions, pore collapse, and particle-level deformation. These particle level processes cannot be measured directly because traditional pressure and velocity sensors provide spatially averaged responses. In order to address this issue, quantum dots (QDs) are investigated as possible meso-scale pressure sensors for probing the shock response of heterogeneous materials directly. Impact experiments were conducted on a QD-polymer film using a laser driven flyer setup at the University of Illinois Urbana-Champaign (UIUC). Time-resolved spectroscopy was used to monitor the energy shift and intensity loss as a function of pressure over nanosecond time scales. Shock compression of a QD-PVA film results in an upward shift in energy (or a blueshift in the emission spectra) and a decrease in emission intensity. The magnitude of the shift in energy and the drop in intensity are a function of the shock pressure and can be used to track the particle scale differences in the shock pressure. The encouraging results illustrate the possible use of quantum dots as mesoscale diagnostics to probe the mechanisms involved in the impact initiation of combustion or intermetallic reactions.

[ES] Los objetivos son 2: 1- Determinar el efecto de la dispersión de la recirculación de gases de escape de alta presión (HP EGR) en las emisiones de NOx y humos en motores diésel de automoción en operaciones de funcionamiento constantes. La investigación cuantifica las emisiones de NOx y humos en función del nivel de dispersión de EGR de alta presión entre cilindros. 2- Explorar los límites del modelado 1D para predecir el movimiento del flujo de los gases en la compleja situación en la que estos entran en los cilindros desde el colector de admisión. Los experimentos se realizaron en un banco de pruebas con un motor diésel de 1.6 litros. Para detectar la dispersión de EGR de alta presión se instaló un sistema de válvulas en los conductos de admisión de cada cilindro para medir la concentración de CO2, por tanto la tasa de EGR, en cada conducto. Se instaló también un sistema de válvulas en el escape para medir las emisiones de NOx en cada cilindro. Se instaló un sensor de humos en la línea de escape, aguas abajo de la turbina, para medir el efecto de la dispersión de EGR de alta presión en las emisiones de humos además del sensor para medir el resto de las emisiones contaminantes aguas abajo de la turbina. Se han estudiado 9 puntos de funcionamiento diferentes con distintas velocidades y niveles de carga. El mapa motor se ha estudiado en profundidad, desde 1250 hasta 3000 rpm y entre 3 y 20 bar de presión media efectiva (BMEP). La tasa de EGR varía entre 5 y 42%, dependiendo del punto de funcionamiento. La geometría del modelo reproduce la del motor diésel de automoción de 1.6 litros en el que se realizaron los ensayos experimentales. Incluyendo la línea de EGR de alta presión que fue instalada para controlar los niveles de dispersión durante los ensayos experimentales. La metodología centrada en las herramientas experimentales combina aparatos de medida tradicional con un sistema de válvulas específico que ofrecen una información precisa en cuanto a la concentración de especies tanto en el colector de admisión como en el de escape. El estudio se realizó a emisiones de NOx constantes para observar el efecto de la dispersión de EGR en los valores de opacidad. La metodología está centrada en las herramientas de modelado, las condiciones de contorno y toda la información necesaria para poner en marcha el modelo proviene de los resultados de los ensayos experimentales medidos con los diferentes sensores y aparatos mencionados anteriormente. Muchos de ellos necesarios para ajustar el modelo. La parte más importante para estudiar la capacidad de predicción del modelo es el diseño del colector de admisión. Es necesario poner especial atención en la orientación de los conductos, y en la estructura interna y la superficie para tratar de ser muy fiel a la geometría real, ya que ello determina la predicción de la dispersión. Esta aproximación de modelado cuasi tridimensional (3D) es posible gracias a un programa específico que importa la información necesaria desde un archivo CAD al programa de modelado 1D. Respecto a la parte experimental, el estudio concluye que cuando la dispersión de EGR es baja, los niveles de opacidad se reducen en todos los puntos de funcionamiento. Sin embargo, por encima de ciertos niveles de dispersión de EGR, la opacidad crece seriamente con diferentes pendientes según el punto de operación. El estudio permite cuantificar este límite de dispersión de EGR. La dispersión de EGR incrementa el consumo de combustible por encima del 6.9%. Respecto a la parte de modelado, el estudio concluye que cuando la distribución de EGR entre conductos medida experimentalmente es asimétrica y presenta un alto patrón de concavidad o convexidad, el modelo no predice adecuadamente la distribución del EGR. El estudio concluye que, aunque en los ensayos experimentales la tasa de EGR afecta a la dispersión de EGR, el modelo 1D no es tan sensible como para predecir esta influencia cuando la tasa de EGR está por debajo del 10%.
[CA] L'objectiu de l'estudi és doble. Per una banda, determinar l'efecte de la dispersió de la recirculació de gasos d'escapament d'alta pressió (HP EGR per les seues sigles en anglès) en les emissions d'òxids de nitrogen (NOx) i fums en motors dièsel d'automoció en operacions de funcionament constants. La investigació quantifica les emissions de NOx i fums en funció del nivell de dispersió d'EGR d'alta pressió entre cilindres. Per una altra banda, l'objectiu és explorar els límits del modelatge unidimensional (1D) per predir el moviment del flux dels gasos en la complexa situació en què aquests entren als cilindres des del col·lector d'admissió. Els experiments van ser realitzats en un banc de proves amb un motor dièsel de 1.6 litres. Per detectar la dispersió d'EGR d'alta pressió es va instal·lar un sistema de vàlvules en els conductes d'admissió de cada cilindre per mesurar el percentatge de CO2 i per tant la taxa d'EGR. De la mateixa manera es va instal·lar també un sistema de vàlvules d'escapament, cilindre a cilindre, per mesurar les emissions de NOx. A més també es va instal·lar un sensor de fums en la línia d'escapament, aigües avall de la turbina, per mesurar l'efecte de la dispersió d'EGR d'alta pressió en les emissions de fums, així com el sensor de mesura de la resta d'emissions aigües avall de la turbina. S'han estudiat 9 punts de funcionament diferents amb distintes velocitats i nivells de càrrega, per la qual cosa el mapa motor s'ha estudiat en profunditat, des de 1250 fins a 3000 rpm i entre 3 i 20 bar de pressió mitjana efectiva (BMEP per les seues sigles en anglès). La taxa d'EGR varia entre 5 i 42 %, depenent del punt de funcionament. La geometria del model reprodueix la geometria del motor dièsel d'automoció d'1.6 litres en el qual es van realitzar tots els assajos experimentals. La metodologia centrada en les ferramentes experimentals combina aparells de mesura tradicional amb un sistema de vàlvules específic que ofereixen una informació precisa quant a la concentració d'espècies tant al col·lector d'admissió com al d'escapament. L'estudi es va realitzar a emissions de NOx constants per observar l'efecte de la dispersió d'EGR en els valors d'opacitat. Quant a la metodologia centrada en les ferramentes de modelatge, les condicions de contorn i tota la informació necessària per posar en marxa el model prové dels resultats dels assajos experimentals mesurats amb els diferents sensors i aparells mencionats anteriorment, molts d'ells necessaris per ajustar el model. La part més important per estudiar la capacitat de predicció del model és el disseny del col·lector d'admissió. És necessari posar especial atenció a l'orientació dels conductes, i a l'estructura interna i la superfície per tractar de ser molt fidel a la geometria real, ja que determina la predicció de la dispersió. Esta aproximació del model quasi-tridimensional (3D) és possible gràcies a un programa específic que importa la informació necessària des d'un arxiu de disseny assistit per ordinador (CAD) al programa de modelat 1D. Respecte a la part experimental, l'estudi conclou que quan la dispersió d'EGR és baixa, els nivells d'opacitat es redueixen en tots els punts de funcionament. Tanmateix, per damunt de certs nivells de dispersió d'EGR, l'opacitat creix seriosament amb diferents pendents segons el punt d'operació. L'estudi permet quantificar aquest límit de dispersió d'EGR. A més, la dispersió d'EGR podria contribuir a incrementar el consum de combustible per damunt del 6.9%. Respecte a la part de modelatge, l'estudi conclou que quan la distribució d'EGR entre conductes mesurada experimentalment és asimètrica i presenta un alt patró de concavitat o convexitat, el model no prediu adequadament la distribució d'EGR. A més, l'estudi conclou que, tot i que en els assajos experimentals la taxa d'EGR afecta a la dispersió d'EGR, el model 1D no és tan sensible com per predir aquesta influència quan la taxa d’EGR està per baix del 10%.
[EN] The objective of the study is twofold. On the one hand, it is to determine the effect of the high pressure (HP) exhaust gas recirculation (EGR) dispersion in automotive diesel engines on NOx and smoke emissions in steady engine operation. The investigation quantifies the smoke emissions as a function of the dispersion of the HP EGR among cylinders. On the other hand, it is to explore the limits of the one-dimensional (1D) modeling to predict the movement of the flow in a complex situation as the gases get into the cylinders from the intake manifold. The experiments are performed on a test bench with a 1.6 liter automotive diesel engine. In order to track the HP EGR dispersion in the intake pipes, a valves system to measure CO2, hence EGR rate, pipe to pipe was installed. In the same way, a valves device to measure NOx emissions cylinder to cylinder in the exhaust was installed too. Moreover a smoke meter device was installed in the exhaust line, downstream the turbine, to measure the effect of the HP EGR dispersion on smoke emissions. A probe to measure the other raw emissions was installed downstream the turbine, too. Nine different engine running conditions were studied at different speed and load, thus the engine map was widely studied, from 1250 rpm to 3000 rpm and between 3 and 20 bar of BMEP. The EGR rate variates between 5 and 42 % depending on the working operation point. The geometry of the model reproduces the geometry of a 1.6 liter diesel automotive engine where the tests were performed. It includes an HP-EGR line and the device that was installed to perform the experiments to control the dispersion. The methodology focused on experimental tools combining traditional measuring devices with a specific valves system which offers accurate information about species concentration in both the intake and the exhaust manifolds. The study was performed at constant raw NOx emissions to observe the effect of the EGR dispersion in the opacity values. Regarding the methodology focused on modeling tools, the boundary conditions and all the necessary information to run the model comes from experimental results measured with the different sensors and devices mentioned before. Much of them were needed to adjust the model. The most important part of the modeling to study the capacity of the prediction of the EGR dispersion is the layout of the intake manifold. It is necessary put special attention to the orientation of the pipes, and the internal structure and surface trying to mimic the real geometry because it determinates the prediction of the dispersion. This approximation to quasi-three-dimensional (3D) modeling is possible thanks to a specific software that imports the necessary information from a computer-aided design (CAD) file to the 1D modeling software. Concerning the experimental results, the study leads to conclude that when the EGR dispersion is low, the opacity presents reduced values in all operation points. However, above a certain level of EGR dispersion, the opacity increases dramatically with different slopes depending on the engine running condition. This study allows quantifying this EGR dispersion threshold. In addition, the EGR dispersion could contribute to an increase in the engine fuel consumption up to 6.9%. Regarding to the modeling part, the study concludes that when the experimental EGR distribution among pipes is asymmetric and presents high concavity or convexity spatial pattern, the model does not predict properly the EGR distribution. In addition, the study concludes that, although in the experimental tests the EGR rate affects to the EGR dispersion, the 1D model is not too sensitive to predict this influence when the EGR rate is lower than 10%.
The respondent wishes to acknowledge the financial support received by contract FPI 2015 S2 3101 of Programa de Apoyo a la Investigación y Desarrollo (PAID) from Universitat Politècnica de València (UPV).
Miguel García, J. (2021). Analysis of the high pressure EGR dispersion among cylinders in automotive diesel engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/161889
TESIS

Le transport routier est responsable d’une partie des émissions de polluants sur la planète. Conscient de ce problème, des lois sur les émissions des véhicules sont régulièrement votées afin de réduire l’impact environnemental du transport automobile. Ces lois de plus en plus restrictives ont poussé les fabricants automobiles à réduire la taille des moteurs essence et à utiliser des procédés d’injection directe afin d’augmenter le ratio puissance/volume des moteurs et réduire la consommation. Cependant avec l’utilisation de l’injection directe, de nouveaux problèmes apparaissent, notamment la production de particules fines, elles-mêmes réglementées. Cette thèse s’inscrit dans ce cadre. En effet, les films liquides engendrés par l’injection de carburant sont identifiés comme principaux responsables de la production de particules. Dans ce contexte, les films liquides sont étudiés expérimentalement à l’aide d’un injecteur haute pression disposant de 3 trous. Les aspects dynamiques de création et d’étalement du film liquides sont étudiés et modélisés. S’en suit une étude thermique de l’interaction entre le spray et la paroi. Afin de caractériser les pertes de chaleur observées lors de l’impact, ces pertes thermiques étant responsables d’un délai dans la vaporisation du carburant et donc d’inhomogénéités du mélange au moment de la combustion, une modélisation de ces pertes et du transfert thermique associé est aussi proposée. Enfin une étude des taux d’évaporation de plusieurs alcanes purs puis de mélanges est proposée. Ces mesures ont servi à la calibration d’un modèle numérique d’évaporation de films fins de carburants sur des parois chaudes. Autour de ces différentes études, une campagne d’essais moteurs a été effectuée. L’objectif est de confirmer que les études expérimentales faites en laboratoires sont bien transposables (moyennant la prise de certaines précautions) aux moteurs automobiles. Les conclusions des différentes études sont finalementproposées
The road transport is responsible of a considerable amount of pollutants emissions at the worldwide scale. To tackle this issue, many laws are trying to give a framework to reduce the emissions at the global scale. The law are always more restrictive, and they oriented the car manufacturers to the reduction of their gasoline engine size. This phenomenon, called downsizing, lead to the use of direct injection in order to improve the power/volume ratio of the engine. However, with direct injection the problem of particle emissions arose. Indeed, the liquid film generated during the injection process are responsible of inhomogeneities in the combustion chamber which lead to particles formation. In this context, the study of the fuel films in the combustion chamber is a major concern. To perform this study several experimental apparatus are designed in this thesis. A high-pressure 3-hole solenoid injector is used in order to generate liquid films. The generation and the spreading of the liquid films is observed and modelled. Then the thermal aspects of the spray impingement is studied, to characterise the local heat transfer. These thermal loss are delaying the evaporation of the liquid film, which will lead to inhomogeneities in the combustion chamber and particle generation. A modelling of the heat transfer is also proposed, finally the evaporation rate of alkanes films is proposed. Mono and multicomponents films are studied, these measures were used to calibrate a numerical model for the evaporation of thin liquid films on hot walls. Together with the previous experimental investigationsand models a test campaign on a real engine has been held. The objective is to confirm that, the results produced out of the engine are transposable to the engine (with careful attention). Conclusions on the different aspects are then presented

Thesis (Ph.D.)--Aerospace Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Seitzman, Jerry; Committee Member: Jagoda, Jechiel; Committee Member: Lieuwen, Tim; Committee Member: Menon, Suresh; Committee Member: Docquier, Nicolas; Committee Member: Huey, Gregory.

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).

Le monoxyde d’azote (NO) est un polluant atmosphérique responsable d’effets nuisibles sur l’environnement et la santé. Afin de mieux contrôler ces émissions, il est indispensable de comprendre et de maîtriser leur formation,en particulier lors de la combustion à haute pression, domaine d’application industrielle (cas des turbines à gaz,des moteurs…). On distingue quatre voies principales de formation de NO : la voie thermique, la voie du NO précoce, la voie NNH et la voie N2O. L’objectif de cette thèse à caractère expérimentale est de compléter la base de données expérimentale déjà existante nécessaire à la compréhension et à l’identification de la contribution de chaque voie à la formation du NO à haute pression.Dans cette thèse, un dispositif de brûleurs à contre-courants a été utilisé pour étudier la structure de flammes laminaires, prémélangées à haute pression. Les profils de concentration de NO dans les flammes CH4/O2/N2 à différentes richesses (Фc =0,7-1,2) et différentes pressions (P=0,1-0,7 MPa) ont été mesurés par Fluorescence Induite par Laser. L’effet de l’ajout d’hydrogène (80%CH4/20%H2 : Application Hythane®) sur la formation de NO a également été étudié dans les flammes pauvres CH4/O2/N2. Le mécanisme cinétique GDF-Kin®3.0_NCN a été comparé aux mesures de NO disponibles dans la littérature ainsi qu’aux simulations des mécanismes cinétiques du Gaz Research Institute (version 2.11 et 3.0). Ces trois mécanismes ont été ensuite comparés aux mesures expérimentales réalisées dans ces travaux de thèse
The nitric oxide (NO) is a pollutant responsible of detrimental effects on the environment and health. To better control these emissions, it’s crucial to understand and to control their formation, in particular during the combustion process at high pressure, area of industrial applications (gas turbines, engines…).There are four major routes of the NO formation: the thermal route, the prompt-NO route, the NNH route and theN2O route. The aim of this experimental thesis is to complete the existing experimental database which isnecessary to the understanding and the identification of the contribution from each route to the NO formation at high pressure.In this thesis, a facility of two twin counter-flow burners was used to study the structure of the laminar, premixed flames at high pressure. Experimental NO concentration profiles have been measured in CH4/O2/N2 flames for arange of equivalence ratio (from 0.7 to 1.2) and pressures (from 0.1 to 0.7 MPa) by Laser Induced Fluorescence.The effect of adding hydrogen (80%CH4/20%H2: Hythane® application) on the NO formation has been also studied in lean CH4/O2/N2 flames. The GDF-Kin®3.0_NCN kinetic mechanism has been compared to experimental data from the literature and also compared to the simulations from the Gas Research Institute mechanisms (version 2.11 and 3.0). These three mechanisms have been finally compared to the experimental data from this thesis