Depuis plusieurs années, la diminution des réserves de pétrole incite les différents pays à accroitre leur indépendance énergétique. De plus, diminuer l’impact environnemental de la voiture est devenu l’une des priorités de notre société. En ce sens, les normes Européennes anti-pollution sont devenues plus strictes, tandis que certains polluants sont pointés du doigt pour avoir un impact néfaste sur la santé et l’environnement. Pour répondre à cette double problématique, l’utilisation de biocarburants de type alcools dans les moteurs à allumage commandé est l’une des voies envisagées. Ce virage a déjà été entrepris à petite échelle par l’Union Européenne qui a tout d’abord autorisé l’ajout de 5%, puis de 10% d’éthanol dans l’essence. En plus de l’éthanol déjà commercialisé, le Biobutanol, biocarburant de seconde génération, apparait comme un candidat à fort potentiel pour une utilisation dans les moteurs à allumage commandé. L’objectif de ce travail de thèse est d’étudier le potentiel de l’utilisation de mélanges isooctane/butanol dans les moteurs à allumage commandé, en termes de performances et d’émissions polluantes. De plus, ces résultats sont comparés à ceux de mélanges isooctane/éthanol. Le dégagement de chaleur dans un moteur à allumage commandé est en partie piloté par la vitesse de combustion laminaire. Cette caractéristique a été étudiée de manière expérimentale et numérique pour différentes conditions initiales (pression et richesse) dans une enceinte à volume constant. Puis, une étude sur les premières étapes de la propagation de la combustion a été réalisée dans un moteur monocylindre à accès optique. Ces résultats en moteur ont été corrélés avec les informations laminaires. Enfin, les émissions de polluants réglementés et non-réglementés, ainsi que les performances ont été étudiées dans un moteur monocylindre à allumage commandé. Une baisse de la plupart de ces émissions a été observée avec l’ajout des deux alcools. / For the past few years, the oil stock decrease encourages the different countries to increase their energy independence. Moreover, reducing the environmental impact of transportation became one of the priorities of our society. In this way, European emissions standards are stricter while several pollutants have been identified to have a negative impact on health and the environment. To answer this double problem, the use of alcohols biofuels in spark-ignition engines is one the promising ways. The European Union have already taken a small step in that direction by allowing a maximum of 10% of ethanol into gasoline. As well as ethanol is already marketed, Biobutanol, a 2nd generation biofuel, appears as a serious candidate with a strong potential for a spark-ignition engines use. The objective of this dissertation is to study the potential of the iso-octane/butanol blends use in spark-ignition engines, in terms of performance and pollutants emissions. Moreover, these results are compared to isooctane/ethanol blends. The heat release in spark-ignition engine is piloted for a part by laminar burning velocity. This characteristic was studied experimentally and numerically for different initial conditions (pressure and equivalence ratio) in a constant volume bomb. Then, the early flame kernel growth was studied in a spark-ignition single cylinder engine equipped with optical accesses. Those results were correlated with the results on the laminar burning velocity. Finally, regulated and non-regulated pollutants emissions and engine performance were investigated in a spark-ignition single cylinder engine. A decrease of most pollutant emissions was observed with both alcohols addition.

Uma nova metodologia para a criação de mapas base de injeção eletrônica de combustível para motores de combustão interna de ignição a centelha é apresentada e seu comportamento é comparado com os resultados fornecidos pela metodologia MVEM. A partir da utilização de equacionamentos da literatura, é feita uma modelagem do ciclo ideal Otto para um motor genérico alternativo monocilíndrico de 500 cm³ de volume deslocado. É modelada também uma válvula do tipo borboleta genérica de 0,06 m³ de diâmetro que opera tanto em regime subsônico quanto sônico. A pressão à jusante da borboleta é calculada para aberturas de 5° a 88,64°. Os modelos são acoplados a partir da vazão mássica de ar admitida, que é o parâmetro principal, sendo programados e simulados usando o programa comercial EES. O mapa base de pressão por abertura de borboleta por rotação resultante mostra o detalhe de descontinuidade pelo uso das equações de vazão mássica juntamente com a imposta pelas equações de coeficiente de descarga, implicando na mudança brusca de valores de pressão calculados para a região de abertura menor que 20%. O mapa de vazão mássica de combustível por rotação e por abertura de borboleta para uma razão estequiométrica de 14,67 também é gerado. Nele é possível observar a demanda por vazão mássica de combustível para cada rotação e abertura da válvula borboleta mostrando o caminho a ser seguido pelo motor para que seja atingida a vazão mássica necessária para obter-se a relação ar/combustível desejada. A metodologia proposta gera mapas base de combustível para módulos de injeção eletrônica. Os resultados são apresentados na forma de gráficos. O modelo produz resultados satisfatórios, reproduzindo o comportamento da válvula borboleta, comparado com a literatura. / A new methodology for EMS base maps to the internal combustion spark ignition engines is presented. Its behavior is compared with results from the MVEM methodology. From the technical literature an ideal Otto cycle for a generic reciprocating single cylinder engine with 500 cm³ of displaced volume. Also, throttle valve with a diameter of 0.06 m of diameter operating in subsonic and sonic flow regime is modeled. The downstream pressure is calculated for throttle openings of 5° to 88.64°. The models are coupled using the engine air mass flow rate as the main parameter, being programmed and simulated using a commercial EES software. The base map of pressure versus throttle opening and engine speed shows the discontinuity detail imposed from the mass flow and discharge coefficient equations, resulting into a abrupt change of pressure values calculated for an opening region less than 20%. The fuel mass flow versus revolutions per minute versus throttle valve opening for stoichiometric air fuel ratio of 14.67 is also generated. In such map it is possible to show the fuel mass flow demand for each rotation and throttle opening showing the path to be followed by the engine to reach the mass air flow needed to reach the target air fuel ratio. This methodology generates base fuel maps for electronic fuel injection modules. The results are presented in graph forms. The model presents satisfactory results that reproduce the throttle valve behavior, compared to the literature.

Uma nova metodologia para a criação de mapas base de injeção eletrônica de combustível para motores de combustão interna de ignição a centelha é apresentada e seu comportamento é comparado com os resultados fornecidos pela metodologia MVEM. A partir da utilização de equacionamentos da literatura, é feita uma modelagem do ciclo ideal Otto para um motor genérico alternativo monocilíndrico de 500 cm³ de volume deslocado. É modelada também uma válvula do tipo borboleta genérica de 0,06 m³ de diâmetro que opera tanto em regime subsônico quanto sônico. A pressão à jusante da borboleta é calculada para aberturas de 5° a 88,64°. Os modelos são acoplados a partir da vazão mássica de ar admitida, que é o parâmetro principal, sendo programados e simulados usando o programa comercial EES. O mapa base de pressão por abertura de borboleta por rotação resultante mostra o detalhe de descontinuidade pelo uso das equações de vazão mássica juntamente com a imposta pelas equações de coeficiente de descarga, implicando na mudança brusca de valores de pressão calculados para a região de abertura menor que 20%. O mapa de vazão mássica de combustível por rotação e por abertura de borboleta para uma razão estequiométrica de 14,67 também é gerado. Nele é possível observar a demanda por vazão mássica de combustível para cada rotação e abertura da válvula borboleta mostrando o caminho a ser seguido pelo motor para que seja atingida a vazão mássica necessária para obter-se a relação ar/combustível desejada. A metodologia proposta gera mapas base de combustível para módulos de injeção eletrônica. Os resultados são apresentados na forma de gráficos. O modelo produz resultados satisfatórios, reproduzindo o comportamento da válvula borboleta, comparado com a literatura. / A new methodology for EMS base maps to the internal combustion spark ignition engines is presented. Its behavior is compared with results from the MVEM methodology. From the technical literature an ideal Otto cycle for a generic reciprocating single cylinder engine with 500 cm³ of displaced volume. Also, throttle valve with a diameter of 0.06 m of diameter operating in subsonic and sonic flow regime is modeled. The downstream pressure is calculated for throttle openings of 5° to 88.64°. The models are coupled using the engine air mass flow rate as the main parameter, being programmed and simulated using a commercial EES software. The base map of pressure versus throttle opening and engine speed shows the discontinuity detail imposed from the mass flow and discharge coefficient equations, resulting into a abrupt change of pressure values calculated for an opening region less than 20%. The fuel mass flow versus revolutions per minute versus throttle valve opening for stoichiometric air fuel ratio of 14.67 is also generated. In such map it is possible to show the fuel mass flow demand for each rotation and throttle opening showing the path to be followed by the engine to reach the mass air flow needed to reach the target air fuel ratio. This methodology generates base fuel maps for electronic fuel injection modules. The results are presented in graph forms. The model presents satisfactory results that reproduce the throttle valve behavior, compared to the literature.

Uma nova metodologia para a criação de mapas base de injeção eletrônica de combustível para motores de combustão interna de ignição a centelha é apresentada e seu comportamento é comparado com os resultados fornecidos pela metodologia MVEM. A partir da utilização de equacionamentos da literatura, é feita uma modelagem do ciclo ideal Otto para um motor genérico alternativo monocilíndrico de 500 cm³ de volume deslocado. É modelada também uma válvula do tipo borboleta genérica de 0,06 m³ de diâmetro que opera tanto em regime subsônico quanto sônico. A pressão à jusante da borboleta é calculada para aberturas de 5° a 88,64°. Os modelos são acoplados a partir da vazão mássica de ar admitida, que é o parâmetro principal, sendo programados e simulados usando o programa comercial EES. O mapa base de pressão por abertura de borboleta por rotação resultante mostra o detalhe de descontinuidade pelo uso das equações de vazão mássica juntamente com a imposta pelas equações de coeficiente de descarga, implicando na mudança brusca de valores de pressão calculados para a região de abertura menor que 20%. O mapa de vazão mássica de combustível por rotação e por abertura de borboleta para uma razão estequiométrica de 14,67 também é gerado. Nele é possível observar a demanda por vazão mássica de combustível para cada rotação e abertura da válvula borboleta mostrando o caminho a ser seguido pelo motor para que seja atingida a vazão mássica necessária para obter-se a relação ar/combustível desejada. A metodologia proposta gera mapas base de combustível para módulos de injeção eletrônica. Os resultados são apresentados na forma de gráficos. O modelo produz resultados satisfatórios, reproduzindo o comportamento da válvula borboleta, comparado com a literatura. / A new methodology for EMS base maps to the internal combustion spark ignition engines is presented. Its behavior is compared with results from the MVEM methodology. From the technical literature an ideal Otto cycle for a generic reciprocating single cylinder engine with 500 cm³ of displaced volume. Also, throttle valve with a diameter of 0.06 m of diameter operating in subsonic and sonic flow regime is modeled. The downstream pressure is calculated for throttle openings of 5° to 88.64°. The models are coupled using the engine air mass flow rate as the main parameter, being programmed and simulated using a commercial EES software. The base map of pressure versus throttle opening and engine speed shows the discontinuity detail imposed from the mass flow and discharge coefficient equations, resulting into a abrupt change of pressure values calculated for an opening region less than 20%. The fuel mass flow versus revolutions per minute versus throttle valve opening for stoichiometric air fuel ratio of 14.67 is also generated. In such map it is possible to show the fuel mass flow demand for each rotation and throttle opening showing the path to be followed by the engine to reach the mass air flow needed to reach the target air fuel ratio. This methodology generates base fuel maps for electronic fuel injection modules. The results are presented in graph forms. The model presents satisfactory results that reproduce the throttle valve behavior, compared to the literature.

Thesis deals with design of the experimental single-cylinder spark ignition engines for research purposes. The main purpose of this work is the design crankcase. Summary of possible constructions of spark ignition engines is included. Basic dimensions and 3-D design of the experimental engine resulted from the summary. The numerical analysis of proposed crankcase in ADAMS (MBS) and ANSYS (FEM) software environment is also part of the work. Generally, the proposed solution of the experimental engine was focused on the universality and simplicity of the design.

The main aim of this diploma thesis is to design two different types of air throttles in the intake manifold and compare their influence on a loss of dynamics of the flow of drawn air. The main purpose is to compare the mass flow for wholly opened air throttle. It deals with creating CDF model of intake manifold by using 3D scanner Atos and software Pro/Engineer WF5. During the work, the results of the CFD analysis were used for a real testing.

This master’s thesis deals with the design of the throttle body of the intake manifold of a spark-ignition engine with regards to minimizing throttle loses at full engine load. The first part of this thesis focuses on the elements of intake tract structure on contemporary combustion engine including their design solutions and the theory of flow. The thesis also describes the creation of the 3-D CAD model of intake manifold with a throttle body and the description of the CFD flow simulation with the evaluation of resul.

L'optimisation des systèmes d'allumage est un paramètre critique pour la définition des foyers de combustion industriels. Des simulations aux grandes échelles (ou LES pour Large-Eddy Simulation) d'un brûleur de type bluff-body non pré-mélangé ont été menées afin de comprendre l'influence de la position de la bougie sur la probabilité d'allumage. La prise en compte de la combustion est basée sur une méthode de tabulation de la chimie détaillée (PCM-FPI pour Presumed Conditional Moments - Flame Prolongation of ILDM). Les résultats de ces simulations ont été confrontés des résultats expérimentaux disponibles dans la littérature. Dans un premier temps, les mesures de vitesse et du champ de richesse à froid sont comparées aux résultats de la simulation pour évaluer les capacités de prédiction en terme de structure de l'écoulement et de mélange turbulent. Un suivi temporel des vitesses et de la fraction de mélange est réalisé à différents points pour déterminer les fonctions de densité de probabilité (ou PDF)des variables caractéristiques de l'écoulement, à partir des champs résolus en LES. Les PDFs ainsi obtenues servent l'analyse des phénomènes d'allumages réussis ou déficients rencontrés expérimentalement. Des simulations d'allumage forcé ont été effectuées pour analyser les différents scénarios de développement de la flamme. Les corrélations entre les valeurs locales (fraction de mélange, vitesse) autour de la position d'allumage et les chances de succès de développement du noyau de gaz brûlés sont alors discutées. Enfin, une extension de la méthode PCM-FPI avec prise en compte des effets d'étirement est développée à l'aide d'une analyse asymptotique, puis confrontée aux résultats de mesures expérimentales. / The optimization of the ignition process is a crucial issue in the design of many combustion systems. Large eddy simulation (LES) of a conical shaped bluff-body turbulent non-premixed burner has been performed to study the impact of spark location on ignition success. The chemistry part of the simulation is done using tabulated detailed chemistry approach. This burner was experimentally investigated by Ahmed et al at Cambridge (UK). The present work focuses on the case without swirl for which detailed measurements are available. First, cold fkow measurements of velocities and mixture fraction are compared with their LES counterparts, to assess the prediction capabilities of simulations in terms of flow and turbulent mixing. Time history of velocities and mixture fraction are recorded at selected spots, to probe the resolved probability density function (pdf) of flow variables, in an attempt to reproduce, from the knowledge of LES resolved instantaneous flow conditions, the experimentally observed reasons of success or failure of spark ignition. A flammability map is also constructed from the resolved mixture fraction pdf and compared with its experimental counterpart. LES of forced ignition is then performed using flamelet fully detailed tabulated chemistry combined with presumed pdfs (PCM-FPI). Various scenarios of flame kernel development are analyzed and correlated with typical flow conditions observed in this burner. The correlations between velocities and mixture fraction values at the sparking time and the success or failure of ignition are then further discussed and analysed. The rate of flame development during successful or unsuccessful ignition events are analysed and compared against experimental observations. Finally, from asymptotic flame analysis, a novel approach has been proposed to include flame straining effects in the PCM-FPI method developped at CORIA-CNRS. The new model overcomes the problem associated with classical PCM-FPI closure to model kernel quenching due to intense local turbulence. Computations are done including the flame straining effects and the effect brought by the new model on kernel development is analysed in detail.

<p>A novel two-loop estimation and control strategy is proposed to reduce the natural gas (NG) spark-ignition (SI) engine tail pipe emissions, with focus on the outer loop development. In the outer loop, an fractional oxidation state (FOS) estimator consisting of a three-way catalyst (TWC) model and an extended Kalman-filter is used to estimate the real-time TWC's FOS, and a robust controller is used to control the first-half TWC's FOS by manipulating the desired engine lambda (i.e., air–fuel equivalence ratio; lambda=1 at stoichiometry). The outer loop estimator and controller are combined with an industry-production baseline inner loop controller, which controls the engine $\lambda$ based on the desired lambda value. This novel two-loop control strategy reduces more CH4 and NOx emissions over no-outer-loop control strategy and the conventional two-loop control strategies through simulation. </p> <p><br></p> <p>Engine with and without fuel cut-off are both investigated. Although fuel cut-off brings better fuel economy, it also over-oxidizes the TWC during fuel cut events, which makes the FOS-based controller's competence in NOx reduction over non-FOS-based controllers less significant. By comparing simulation results with and without fuel cut-off, it shows huge potential for much better emission result if fuel cut-off's side effect can be alleviated. Considering that fuel cut-off generally being cutting engine fueling during zero load periods and introducing unreacted oxygen into the after-treatment system, the best way of dealing with the issue is to cut off or reduce the oxygen input to the TWC during those events. Several advanced engine technologies such as cylinder deactivation and exhaust gas re-circulation are good candidates to approach this issue. </p> <p><br></p> <p>An industry-production Cummins B6.7N natural gas SI engine was installed in the Ray W. Herrick Laboratories for study of variable valve actuation (VVA) technology, for the purpose of evaluating/improving SI engine's fuel efficiency, emission reduction, and engine knock resistance. A one-dimensional, physics-based natural gas SI engine model was investigated and calibrated in GT-Power software. To calculate the burn rates in the cylinder, three different pressure analysis methods were investigated and implemented. It is observed that all six cylinders' pressure curves are different, which in turn render different burn rates cylinder-to-cylinder. Cylinder with a higher peak cylinder pressure has a faster burn rate. Each operating condition has its unique pressure curve, and their burn rates are different under different operating conditions. Considering that the burn rate profile can vary cylinder-to-cylinder and operation-to-operation, to make the GT combustion model work for a larger range of loads, a fixed burn rate model may help in the preliminary research phase, but a predictive combustion model is more preferable.</p> <p><br></p> <p>The GT-Power model's VVA capability is investigated, where intake valve closure (IVC) modulation and cylinder de-activation (CDA) are built and analyzed. To mitigate TWC's over-oxidation issue during engine's fuel cut-off events, the CDA is implemented and simulated to demonstrate its benefit on further emission and fuel consumption reductions.</p>

Call number: LD2668 .T4 1985 S335 / Master of Science