According to the current governmental regulations, all diesel buses will be replaced in the United States and the European market within the next ten years. There are over 60,000 buses in the United States and each year over 3,000 new buses of approximately 40 feet in length are purchased. The bus market has a growth rate of four to five percent per year over the last two years. The improvements in technology offered by United States companies prove unsatisfactory in terms of bus performance and the emissions of new buses. The energy crisis in the United States and concern over the health hazards of the diesel fuel exhaust gases and particulates, alternative fuel vehicles are in great demand in the transit market world wide.

The upward trend in internal combustion engine efficiency is likely driven by the depletion of fossil fuels. Since no replacement in sight can deliver energy comparable to the conventional oil, there is a need to use it more rationally and effectively. Thermal barrier coatings have been seen for a long time as a solutionto increase the thermal efficiency of gas turbine engines but suffer from the lackof strong applicability in internal combustion engines. This is due to the different restrictions when comparing the environment on the gas turbines and in internal combustion engines. To overcome this problem and, at the same time, expand the application field of thermal barrier coatings, more efforts need to be devoted.In this work, different top coat materials using various deposition techniques were evaluated and categorized in three different thermal barrier coating (TBC) architectures. The first was the lamellar yttria-stabilized zirconia (YSZ) top coat deposited by atmospheric plasma spray (APS), used as a reference sample. The second architecture was a columnar suspension plasma spray (SPS) TBC with YSZ and gadolinium zirconate (GZO) top coat. The SPS process can produce avariety of microstructures, and they were, for the first time, tested in an internal combustion engine. The third architecture was an SPS top coat, with an additional layer on the top, called a sealing layer of either metallic or ceramic material, both never investigated in a diesel engine application earlier. For the thermophysical properties investigation, a combination of laser flashanalysis (LFA) and modeling with object-oriented finite element (OOF) was employed to understand the properties in all the applications. The performance of the coatings was evaluated in two different ways, by thermal cyclic tests, basedon the TBCs behavior under cyclic thermal loads and by single-cylinder engine experiment. The characterization of the coatings was done by scanning electron microscope (SEM) before and after the thermal cyclic tests.The performance properties were correlated with coatings microstructure and thermophysical properties. It was shown that a columnar TBC produced by SPS had a superior engine efficiency in the single cylinder engine experiment.

Indiana University-Purdue University Indianapolis (IUPUI) / Ignition by a jet of hot combustion product gas injected into a premixed combustible mixture from a separate pre-chamber is a complex phenomenon with jet penetration, vortex generation, flame and shock propagation and interaction. It has been considered a useful approach for lean, low-NOx combustion for automotive engines, pulsed detonation engines and wave rotor combustors. The hot-jet ignition constant-volume combustor (CVC) rig established at the Combustion and Propulsion Research Laboratory (CPRL) of the Purdue School of Engineering and Technology at Indiana University-Purdue University Indianapolis (IUPUI) is considered for numerical study. The CVC chamber contains stoichiometric methane-hydrogen blends, with pre-chamber being operated with slightly rich blends. Five operating and design parameters were investigated with respect to their eff ects on ignition timing. Di fderent pre-chamber pressure (2, 4 and 6 bar), CVC chamber fuel blends (Fuel-A: 30% methane + 70% hydrogen and Fuel-B: 50% methane + 50% hydrogen by volume), active radicals in pre-chamber combusted products (H, OH, O and NO), CVC chamber temperature (298 K and 514 K) and pre-chamber traverse speed (0.983 m/s, 4.917 m/s and 13.112 m/s) are considered which span a range of fluid-dynamic mixing and chemical time scales. Ignition delay of the fuel-air mixture in the CVC chamber is investigated using a detailed mechanism with 21 species and 84 elementary reactions (DRM19). To speed up the kinetic process adaptive mesh refi nement (AMR) based on velocity and temperature and multi-zone reaction technique is used. With 3D numerical simulations, the present work explains the e ffects of pre-chamber pressure, CVC chamber initial temperature and jet traverse speed on ignition for a speci fic set of fuels. An innovative post processing technique is developed to predict and understand the characteristics of ignition in 3D space and time. With the increase of pre-chamber pressure, ignition delay decreases for Fuel-A which is the relatively more reactive fuel blend. For Fuel-B which is relatively less reactive fuel blend, ignition occurs only for 2 bar pre-chamber pressure for centered stationary jet. Inclusion of active radicals in pre-chamber combusted product decreases the ignition delay when compared with only the stable species in pre-chamber combusted product. The eff ects of shock-flame interaction on heat release rate is observed by studying flame surface area and vorticity changes. In general, shock-flame interaction increases heat release rate by increasing mixing (increase the amount of deposited vorticity on flame surface) and flame stretching. The heat release rate is found to be maximum just after fast-slow interaction. For Fuel-A, increasing jet traverse speed decreases the ignition delay for relatively higher pre-chamber pressures (6 and 4 bar). Only 6 bar pre-chamber pressure is considered for Fuel-B with three di fferent pre-chamber traverse speeds. Fuel-B fails to ignite within the simulation time for all the traverse speeds. Higher initial CVC temperature (514 K) decreases the ignition delay for both fuels when compared with relatively lower initial CVC temperature (300 K). For initial temperature of 514 K, the ignition of Fuel-B is successful for all the pre-chamber pressures with lowest ignition delay observed for the intermediate 4 bar pre-chamber pressure. Fuel-A has the lowest ignition delay for 6 bar pre-chamber pressure. A speci fic range of pre-chamber combusted products mass fraction, CVC chamber fuel mass fraction and temperature are found at ignition point for Fuel-A which were liable for ignition initiation. The behavior of less reactive Fuel-B appears to me more complex at room temperature initial condition. No simple conclusions could be made about the range of pre-chamber and CVC chamber mass fractions at ignition point.

Recent imaging studies have provided a new conceptual model of the internal structure of direct injection diesel fuel jets as well as empirical correlations predicting jet development and structure. This information was used to create a diesel cycle simulation model using C language including compression, fuel injection and combustion, and expansion processes. Empirical relationships were used to create a new mixing-limited zero-dimensional model of the diesel combustion process. During fuel injection five zones were created to model the reacting fuel jet: 1) liquid phase fuel 2) vapor phase fuel 3) rich premixed products 4) diffusion flame sheath 5) surrounding bulk gas. Temperature and composition in each zone is calculated. Composition in combusting zones was calculated using an equilibrium model that includes 21 species. Sub models for ignition delay, premixed burn duration, heat release rate, and heat transfer were also included. Apparent heat release rate results of the model were compared with data from a constant volume combustion vessel and two single-cylinder direct injection diesel engines. The modeled heat release results included all basic features of diesel combustion. Expected trends were seen in the ignition delay and premixed burn model studies, but the model is not predictive. The rise in heat release rate due to the diffusion burn is over-predicted in all cases. The shape of the heat release rate for the constant volume chamber is well characterized by the model, as is the peak heat release rate. The shape produced for the diffusion burn in the engine cases is not correct. The injector in the combustion vessel has a single nozzle and greater distance to the wall reducing or eliminating wall effects and jet interaction effects. Interactions between jets and the use of a spray penetration correlation developed for non-reacting jets contribute to inaccuracies in the model.

Os motores de combustão interna (MCI) têm sido usados pela humanidade há mais de 100 anos e ainda continuarão por muito tempo em virtude da sua alta confiabilidade e baixo custo de produção. No entanto, eles apresentam grande impacto ambiental em relação à emissão de \'CO IND.2\'. Atualmente, diversos trabalhos têm sido realizados com o objetivo de reduzir o consumo de combustíveis, o que conseqüentemente resulta em redução de emissões. Esses trabalhos englobam melhoramentos de projeto, desenvolvimento de novos materiais e lubrificantes de maior desempenho. No presente trabalho desenvolveu-se um lubrificante que contém partículas magnéticas constituídas de Compostos Intermetálicos Lubrificantes (CIL), que foi avaliado em tribômetro do tipo quatro esferas. Este lubrificante foi testado nas temperaturas de 60 ºC, 100 ºC e 150 ºC, sob perfil de carga específico e rotação de 1.500 rpm. Comparado com outro óleo de mesmo grau SAE de viscosidade, apresentou desempenho friccional superior, exceto para a temperatura de 150 ºC. Constatou-se que as partículas de CIL atuavam através da combinação da atividade superficial e atração magnética provocada pelo processo friccional das superfícies. Também se realizou um estudo de simulação computacional, com o objetivo de avaliar os efeitos da presença de CIL sobre o desempenho global de um motor de combustão interna, variando-se as viscosidades dos lubrificantes comparados, dentro do mesmo grau SAE. A conclusão é que um motor operando com o óleo formulado com CIL apresentou melhor desempenho do que quando operava com óleo comercial. Ainda se constatou, teoricamente, que dentro de um mesmo grau de viscosidade, o óleo de viscosidade menor pode oferecer ganhos de potência superiores a um motor que opere com outro óleo de viscosidade maior, com uma boa capacidade de proteção contra o desgaste, em virtude da presença das partículas de CIL. / The internal combustion engines have been used for 100 years and they will continue being used for many years, especially because of high reliability and low costs of production. Nevertheless, they produce a lot of \'CO IND.2\' emissions. Nowadays, worldwide, several projects are being performed in order to save fuels and reduce the emissions and for that, new materials and high performance lubricants are being developed. In this work it was developed a lubricant that contained magnetic particles, called lubricant intermetalic compound (CIL) and it was evaluated in a four ball tribometer, under 60 ºC, 100 ºC and 150 ºC, using a specific load profile and a speed of 1.500 rpm. When the magnetic oil was compared with commercial oil, in the same SAE viscosity grade, it presented a better frictional performance, except for 150 ºC. It was verified that the mechanism of the magnetic lubricant was a combination of particles superficial activity and attraction magnetic obtained by frictional process of the surfaces. Also, it was carried out a computational simulation for an internal combustion engine, in order to compare the performance of the magnetic lubricant with commercial oil, and evaluating the effect of the viscosities. The lubricant prepared with CIL presented a power increase, when compared to commercial oil, and for the same grade viscosity, the lower viscosity oil presented a better performance, besides of offering a good protection against wear.

O controle de emissões em veículos pesados está em foco desde a década de 90, com a criação de regulamentações nacionais e internacionais que impõe limites cada vez mais rígidos para as concentrações de poluentes emitidos por estes veículos. O desenvolvimento de novas tecnologias possui papel fundamental neste processo, buscando redução nos níveis de emissões com mínimo impacto negativo no desempenho e no consumo do veículo. Para tanto, o presente trabalho visa avaliar a influência da posição dos dutos de admissão de ar de cabeçotes de motores a combustão interna, especificamente em motores de ignição por compressão (MIC) de 4 válvulas, no escoamento de ar dentro do cilindro. O escoamento do ar e o movimento de swirl são fatores importantes para a mistura e distribuição do combustível injetado, e quando otimizados para uma queima melhor distribuída, contribuem para redução nos níveis de emissões. Procura-se investigar quais direções características dos dutos são determinantes para o escoamento e para o comportamento de swirl do motor através de simulações em fluidodinâmica computacional (Computational Fluid Dynamics - CFD) utilizando o programa CD-adapco STAR-CCM+®. Os resultados de alguns dos cenários simulados são comparados a resultados de testes experimentais realizados em bancada de medição de swirl, no âmbito de outro trabalho sendo desenvolvido no mesmo grupo de projeto. / The emissions control in heavy-duty vehicles has been in focus since the 1990\'s, with the creation of national and international regulations which impose strict limits for pollutant concentrations released by these vehicles. The development of new technologies has a fundamental role in this process, aiming the reduction of emission levels with minimum impact on the performance and fuel consumption of the vehicle. Therefore, the present study aims to evaluate the influence of the position of intake ports in cylinder heads from internal combustion engines, specifically 4-valves compression-ignition (CI) engines, in the in-cylinder air flow. The air flow and swirl motion are important factors for the mixture and distribution of injected fuel, and when optimized for a better distributed combustion, contribute for the reduction of emission levels. This study investigates the characteristic directions of ports which are determinant for the air flow and swirl behaviour of the engine through Computational Fluid Dynamics (CFD) simulations using CD-adapco software STAR-CCM+®. The results from a group of simulated cases are compared to experimental test results from another project, developed on the same project group, performed in a swirl meter test rig.

Nas últimas décadas, a indústria automobilística mundial vem investindo no desenvolvimento tecnológico dos motores, com o objetivo de alcançar melhor eficiência energética e atender às legislações que limitam a quantidade de resíduos tóxicos nos gases de exaustão e menor consumo de combustível. Isso resultou na implantação dos sistemas de gerenciamento eletrônico do motor, que possibilitam funcionalidades para se controlar diversas variáveis do motor, aumentando consideravelmente o rendimento do motor. Este trabalho tem como objetivos explorar a dinâmica de um motor de combustão interna ciclo Otto, os sinais elétricos associados, e os componentes de seu gerenciamento eletrônico. A partir dessas informações, o trabalho apresenta o processo de analise dos sinais elétricos e as estratégias de controle utilizadas em um sistema de gerenciamento real. Assim, são desenvolvidos o hardware e o firmware de uma unidade microcontroladora para gerenciamento eletrônico do motor. O hardware foi elaborado com uma concepção centralizada, ou seja, foi usado apenas um microcontrolador de 32-bit para gerenciar todas as funções. O firmware de controle foi desenvolvido de forma modular baseado em modelos de malha fechada. O modelo matemático do motor foi identificado utilizando técnicas de controle em um veículo real, e a avalidação do modelo foi obtida através de testes em um dinamômetro inercial. / In the last few decades, the world automotive industry has invested in the technological development of the engines, aiming to get better energetic efficiency and comply with legislations that limit the amount of toxic exhaustion gases. This resulted in electronic management systems for engines, which allowed flexibility to control several engine-related variables, considerably increasing the engine efficiency. This work aims to explore the Otto cycle combustion engine dynamics, its electronic signals, and the elements of its electronic management. Based on that information, this work presents the analysis process of the electronic signals, and the control strategies used in a real management system. Then, the hardware and firmware of a microcontroller unity are developed for the electronic management of the engine. The hardware was elaborated with a centralized concept, i.e., only one 32-bit microcontroller was used to control all functions. The control firmware was developed in a modular scheme, based on the closed loop models. The engine mathematical model was identified using control techniques in a real engine. The results were obtained by tests in an inertial dynamometer.

O objetivo do presente trabalho de pesquisa é o desenvolvimento de uma metodologia de monitoramento e detecção de defeitos esporádicos e de difícil diagnóstico, bem como o estudo de caso de sistemas de ignição de motores de combustão interna do ciclo Otto. O estudo visa aumentar a robustez do sistema perante falhas esporádicas de difícil detecção, reduzindo drasticamente o tempo de determinação da origem da falha. Através de testes acelerados e simulados em bancadas, a metodologia indica o estado atual dos componentes do sistema de ignição no tocante ao potencial de ocorrência de falhas esporádicas que afetam a combustão e também a confiabilidade do veículo. Os componentes e sistemas objetos da pesquisa são identificados por meio de um processo de análise de risco e de fatores como: ocorrência de muitos anos de histórico de campo, indicadores de reparos repetitivos, falhas esporádicas e de difícil diagnóstico, quebras de qualidade e do comportamento do sistema de diagnóstico OBD Br-2 (On-Board Diagnostic versão 2) diante de falhas intermitentes. A metodologia também proporciona uma ferramenta de análise de interfaces de componentes, que são fontes de falhas potenciais nem sempre consideradas nos processos de análise. Por meio de testes acelerados desses componentes críticos, é proposta metodologia para análise e correção imediata do processo produtivo de tais componentes, culminando na melhoria da confiabilidade dos processos críticos. A metodologia visa a aumentar a robustez do sistema de ignição, detectando rapidamente potenciais falhas esporádicas de difícil diagnóstico oriundas dos processos de fabricação e corrigindo-as imediatamente, introduzindo, assim, um fator de confiabilidade a um componente ou a um processo crítico cuja criticidade era até então desconhecida. Tal criticidade passa a ser gerenciada com impacto positivo nas emissões de poluentes e na confiabilidade global do conjunto. / The objective of this research work is the development of a methodology to monitor and identify sporadic and difficult to detect failures as well as present a case study on the ignition system of internal combustion engines. Such study aims to increase the system reliability. It also helps to reduce dramatically the time to define the failure root cause. Using accelerated test benches, the methodology will indicate the current situation of the components related to the potential of intermittent failure occurrence which affect the combustion and vehicle reliability. The components and systems of this study are identified by a process risk analysis as well as factors like: occurrence time history, repetitive repair index, sporadic and difficult to detect failures, quality breakdown index, and the behavior of the OBD-2 diagnostic system (On-Board Diagnostic version 2) The methodology will also provide a tool to analyze the components interfaces. Such interfaces are a source of potential failures but are not considered in the analysis process. By means of accelerated tests of such critical parts it will be proposed an analysis methodology and a prompt interference at the production process, increasing the reliability of the critical processes. The methodology aims the system robustness increase of the ignition system detecting very fast the sporadic failure potential on the manufacturing process. By introducing a reliability degree of a component or process it will be managed with a benefic impact on emissions and overall reliability of the ignition system.

A new material system was developed for fabricating the combustion engine of an unmanned aerial vehicle. The material system consisted of a mixture of nanoscale and microscale particles of silicon nitride. Magnesia and yttria were used as sintering additives. The powders were mixed with a paraffin binder system. The binder-powder was analyzed for its properties and molding attributes. The study involved several steps of the development and processing. These steps include torque rheometery analysis, mixing scale-up, property measurements of binder-powder, injection molding, binder removal, sintering, scanning electron microscopy analysis and mechanical properties measurements. Simulations of the injection molding process were conducted to assess the feasibility of manufacturing a ceramic engine and to determine its optimal process parameters. The model building required for the simulation was based on flow and solidification behavior data compiled for the binder-powder mixture. The simulations were performed using the Moldfow software package. A design of experiments approach was set up in order to gain an understanding of critical process parameters as well as identifying a feasible process window. Quality criteria were then analyzed in order to determine the optimal production parameters. The study resulted in the successful development of design parameters that will enable fabrication of silicon nitride engine components by powder injection molding. / Graduation date: 2012

Today, the investigation of fuel economy improvements in internal combustion engines (ICEs) has become the most significant research interest among the automobile manufacturers and researchers. The scarcity of natural resources, progressively increasing oil prices, carbon dioxide taxation and stringent emission regulations all make fuel economy research relevant and compelling. The enhancement of engine performance solely using incylinder techniques is proving increasingly difficult and as a consequence the concept of exhaust energy recovery has emerged as an area of considerable interest. Three main energy recovery systems have been identified that are at various stages of investigation. Vapour power bottoming cycles and turbo-compounding devices have already been applied in commercially available marine engines and automobiles. Although the fuel economy benefits are substantial, system design implications have limited their adaptation due to the additional components and the complexity of the resulting system. In this context, thermo-electric (TE) generation systems, though still in their infancy for vehicle applications have been identified as attractive, promising and solid state candidates of low complexity. The performance of these devices is limited to the relative infancy of materials investigations and module architectures. There is great potential to be explored. The initial modelling work reported in this study shows that with current materials and construction technology, thermo-electric devices could be produced to displace the alternator of the light duty vehicles, providing the fuel economy benefits of 3.9%-4.7% for passenger cars and 7.4% for passenger buses. More efficient thermo-electric materials could increase the fuel economy significantly resulting in a substantially improved business case. The dynamic behaviour of the thermo-electric generator (TEG) applied in both, main exhaust gas stream and exhaust gas recirculation (EGR) path of light duty and heavy duty engines were studied through a series of experimental and modelling programs. The analyses of the thermo-electric generation systems have highlighted the need for advanced heat exchanger design as well as the improved materials to enhance the performance of these systems. These research requirements led to the need for a systems evaluation technique typified by hardware-in-the-loop (HIL) testing method to evaluate heat exchange and materials options. HIL methods have been used during this study to estimate both the output power and the exhaust back pressure created by the device. The work has established the feasibility of a new approach to heat exchange devices for thermo-electric systems. Based on design projections and the predicted performance of new materials, the potential to match the performance of established heat recovery methods has been demonstrated.