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This study has focused on development, optimisation and implementation of the 2-line Planar Laser Induced Fluorescence (2-line PLIF) technique for combustion measurements on a single cylinder optical Gasoline Direct Injection (GDI) engine with both Spark Ignition (SI) and Controlled Auto Ignition (CAI) combustion operations. The CAI combustion was achieved by employing Negative Valve Overlap (NVO). Two excitation wavelengths at 308 nm (directly from a XeCl laser) and 277 nm (via Raman shifting a KrF laser output at 248 nm) were exploited for the measurements. A calibration curve of fluorescence signal intensity ratio of the two laser beams as a function of temperature was obtained by conducting a series of static tests on a specially designed Constant Volume Chamber (CVC). The developed technique was validated by measurements of in-cylinder charge temperature during the compression stroke for both motoring and firing cycles and comparing the PLIF values with the temperature values calculated from in-cylinder pressure data assuming a polytropic compression. Following the validation measurements, the technique was applied to study of fuel spray characteristics and simultaneous measurements of in-cylinder charge temperature and mole fraction of Exhaust Gas Residuals (EGR). Further optimisation of the thermometry technique by enhancing the fluorescence Signal to Noise Ratio (SNR) and improving both the temporal and spatial resolutions as well as measurements precision provided the opportunity to apply the technique to other combustion measurements. The thesis presents the first application of the 2-line PLIF diagnostic in study of direct injection charge cooling effects and study of flame thermal stratification in IC engines.

Finite volume method was employed for analyzing the three-dimensional turbulent flow structures, species distributions, and mixing behaviors of combustion flows in a rotary kiln under various operation conditions. The modified £e-£`turbulence model together with wall functions was adopted. Devolatilization of solid wastes were simulated by gaseous methane (CH4) non-uniformly distributed along the kiln bed. Combustion process was considered as a two-step reaction when primary air entered and mixed with methane gas in the first combustion chamber. Mixing-controlled eddy-dissipation model was employed for predicting the reaction rates of CH4, O2, CO2, CO and H2O. Effects of inleakage air, kiln rotation speed and methane distribution along the kiln bed were also examined. Results show that 128% excess air will get the best combustion efficiency, above which the combustion efficiency will decrease. The temperature and species are not uniformly distributed and are vertically stratified on cross-sectional plane. The combustion efficiency will also be lowered if there is inleakage airflow. Results also show rotation speed and methane distributions have little effect on combustion efficiency.

No description available.

No description available.

L’optimisation des systèmes de production d’énergie par combustion requiert une connaissance précise de la cinétique de combustion. Cependant, la majorité des systèmes de production d’énergie par combustion fonctionnent à haute pression et il est reconnu que la pression a une influence sur la cinétique de combustion. En laboratoire, l’analyse de la structure de flamme laminaire se présente comme un outil puissant pour étudier la chimie de la combustion. A ce jour, la plupart des travaux menés ont été réalisés à des pressions inférieures ou égales à la pression atmosphérique. Au cours de cette thèse, un dispositif expérimental pour l’analyse de structure de flammes laminaires, à contre-courants et à haute pression a été mis en place. Il permet de stabiliser des flammes de CH4/air et CH4/CO2/air jusqu’à 0,7 MPa et l’étude de leur structure par diagnostics laser. Les profils de concentration de OH dans les flammes CH4/air et CH4/CO2/air à différentes richesses (=0,7-1,2) et différentes pressions (P=0,1-0,7 MPa) ont été mesurés par Fluorescence Induite par Laser et calibrés en concentration par absorption laser. Pour cela, la longueur du milieu absorbant a été déterminée par Fluorescence Induite par Plan Laser (PLIF). Une attention particulière a été portée aux corrections du signal de fluorescence prenant en compte l’élargissement de raie et le taux de collisions, qui augmentent avec la pression. Les profils expérimentaux obtenus ont été comparés à la modélisation à l’aide du code de calcul OPPDIF et des mécanismes cinétiques GRI-Mech3.0 et GDFKin®3.0. En parallèle, une analyse spectroscopique des flammes de CH4/air à haute pression a été entreprise. / The optimisation of practical combustion devices requires a detailed knowledge of the combustion kinetic. However, most practical combustion systems operate at high pressure and it is known that pressure has an influence on combustion kinetics. In laboratory, the analysis of laminar flame structure is a powerful tool for studying combustion chemistry. However, most of studies have been realised at pressures under or equal to atmospheric pressure. During this thesis, an experimental device has been implemented for the study of the structure of high pressure counterflow flames. It allows the stabilisation and the study of CH4/air and CH4/CO2/air flame structure through laser diagnostics until 0.7 MPa. CH4/air and CH4/CO2/air flames have been studied for a various range of stoichiometry (equivalence ratios from 0.7 to 1.2) and pressures (0.1 MPa to 0.7 MPa). Experimental OH concentration profiles have been measured by Laser Induced Fluorescence and calibrated by laser absorption. To do this, absorption path length has been determined by Planar Laser Induced Fluorescence (PLIF). Great care has been attached to the determination of the fluorescence signal by taking into account the line broadening and de-excitation by quenching which both arise at high pressure. Experimental data were compared with modeling results obtained through the OPPDIF calculation code with GRI-Mech3.0 and GDFKin®3.0 kinetic mechanisms. In parallel, a spectroscopic analysis of the CH4/air flames has been undertaken.

To contribute to the design of next-generation high performance and low emission combustion devices, this study provides a series of high fidelity numerical simulations of turbulent premixed combustion and autoignition with different clean fuels. The first part of the thesis consists of the direct numerical simulations (DNS) of the lean hydrogen-air turbulent premixed flames at a wide range of Karlovitz number (Ka) conditions up to Ka = 1,126. Turbulence-chemistry interaction is discussed in terms of statistical analysis of the turbulent flame speed and flame structure. Global and local flame speed are separately studied through the fuel consumption speed and displacement speed of the flame front, respectively, and the results are compared with the reference laminar flames as well as similar studies in the literature. The global flame structure is assessed via cross-sectional and conditional averages, and modeling implication is further discussed. Detailed analysis of the local flame structure along the positive and negative curvature is also conducted, providing an understanding of the different behavior of local heat release response. Finally, as the modeling perspectives for Reynolds-averaged Navier-Stokes (RANS) and large eddy simulations (LES), the mean quantities of major species, intermediate species, density, the reaction rate of the progress variable, and heat release rate are assessed in the context of the probability density function (PDF). The second part of the thesis consists of applications of the advanced mathematical tool called the computational singular perturbation (CSP). A skeletal chemical mechanism is developed using the CSP algorithm for the autoignition of methanol and dimethyl ether blends, and the ignition delay time and laminar flame speed are validated for a wide range of mixture conditions. A series of autoignition simulations are carried out in the canonical counter flow mixing layer using the developed skeletal mechanism, and detailed analyses of the autoignition for the methanol and dimethyl ether blends at a wide range of strain rate conditions are provided using the CSP diagnostics tools for a wide range of chemical and fluid combinations.

This document details original numerical studies performed by the author pertaining to the propellant oxidizer, ammonium perchlorate (AP). Detailed kinetic mechanisms have been utilized to model the combustion of the monopropellants AP and ADN, and a two-dimensional diffusion flame model has been developed to examine the flame structure above an AP/HTPB composite propellant. This work was part of an ongoing effort to develop theoretically based, a priori combustion models. The improved numerical model for AP combustion utilizes a “universal” gas-phase kinetic mechanism previously applied to combustion models of HMX, RDX, GAP, GAP/RDX, GAP/HMX, NG, BTTN, TMETN, GAP/BTTN, and GAP/RDX/BTTN. The universal kinetic mechanism has been expanded to include chlorine reactions, thus allowing the numerical modeling of AP. This is seen as a further step in developing a gas-phase kinetic mechanism capable of modeling various practical propellants. The new universal kinetic mechanism consists of 106 species and 611 reactions. Numerical results using this new mechanism provide excellent agreement with AP's burning rate, temperature sensitivity, and final species data. An extensive literature review has been conducted to extract experimental data and qualitative theories concerning ADN combustion. Based on the literature review, the first numerical model has also been developed for ADN that links the condensed and gas phases. The ADN model accurately predicts burning rates, temperature and species profiles, and other combustion characteristics of ADN at pressures below 20 atm. Proposed future work and modifications to the present model are suggested to account for ADN's unstable combustion at pressures between 20 and 100 atm. A two-dimensional model has been developed to study diffusion in composite propellant flames utilizing a vorticity formulation of the transport equations. This formulation allows for a more stable, robust, accurate, and faster solution method compared to the Navier-Stokes formulations of the equations. The model uses a detailed gas-phase kinetic mechanism consisting of 37 species and 127 reactions. Numerical studies have been performed to examine particle size, pressure, and formulation effects on the flame structure above an AP/HTPB propellant. The modeled flame structure was found to be qualitatively similar to the BDP model. Results were consistent with experimental observations. Three different combustion zones, based on particle size and pressure, were predicted: the AP monopropellant limit, the diffusion flame, and a premixed limit. Mechanistic insights are given into AP's unique combustion properties.

京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第24253号 / エネ博第451号 / 新制||エネ||84(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)教授 川那辺 洋, 教授 林 潤, 教授 澄川 貴志 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

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.