High levels of soot-in-oil can cause an increase in engine wear and oil viscosity, thus reducing oil drain intervals. The mechanisms by which soot particles are entrained into the bulk oil are not well understood. The research reported in this thesis addresses questions on the mechanisms of soot transfer to the lubricating oil in light-duty diesel engines with high pressure EGR systems. Deposition as a result of blow-by gas passing the piston ring pack and by absorption to the oil film on the cylinder liner via thermophoresis are soot transfer mechanisms that have been considered in detail. The investigations are based on analytical and simulation studies, and results based on complementary experimental studies are used to validate these. The experimental investigations aimed at evaluating the typical rate of accumulation and size distribution of soot agglomerates in oil. The oil samples analysed were collected during regular services from light-duty diesel engine vehicles. These were representative of vehicles meeting Euro IV and V emission regulation standards driven under real-world conditions. The rate of soot-in-oil was determined by thermogravimetric analysis and results showed a concentration of approximately 1 wt% of soot-in-oil after 15,000 km. The particle size distribution was determined using a novel technique, Nanoparticle Tracking Analysis (NTA), applied for the first time to soot-laden oil samples by the author [1, 2]. Results showed an average particle size distribution of 150 nm, irrespective of oil drain interval. Almost the totality of the particles were between 70 and 400 nm, with micro particles not detected in any of the samples analysed. For the samples investigated in this work, the Euro standard did not influence either the rate of soot deposition or the particles size distribution. To the author’s best knowledge, this is the first time that rate of soot deposition and particles size distribution from oil samples collected from vehicles of different Euro standard driven under real-world conditions are analysed and compared. Exhaust Gas Recirculation (EGR) is a common technique used in diesel engines in order to reduce NO¬x emissions. However, it has the drawback that it increases the production of soot. In this work, particular attention has been given to its effects on the rate of soot deposition in oil. Both its influence on the soot produced during the combustion process and on the soot re-introduced in the combustion chamber by the EGR gas has been investigated through CFD simulations using Kiva-3V. Examining the relative importance of near–surface transport of soot by thermophoresis to the oil film on the liner and from blow-by gases to surfaces in the ring pack shows the former to be the dominant mechanism of soot transfer. EGR increases the rate of deposition of soot on the liner not only by increasing net production of soot, but also through the re-cycled particles. At EGR levels higher than 20%, the contribution of the Re-cycled soot becomes the major source for soot-in-oil. The study of soot deposition was evaluated during the entire engine cycle, including compression stroke and post-Exhaust Valve Opening (EVO) period. Existing deposition models found in the literature typically limit the domain to only from the Start of Injection (SOI) to (EVO) period [3-5]. Results from this thesis indicated that compression stroke and post-EVO period can contribute up to 30% of the total rate of soot deposition into oil.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2012. / Our planet is continuously being depleted of its natural resources leading to a need to conserve energy and the environment. One of the major energy consumers is the conventional internal combustion engine. Many attempts have been made to make these conventional internal combustion engines more efficient focusing mostly on the combustion side of the engine. The focus of this study is on the modification of the reciprocating and rotating components of the sub-assembly of a conventional internal combustion engine. An in-depth review was carried out on the fundamentals of spark ignition internal combustion engines and savings on fuel consumptions. A prototype single piston internal combustion engine was developed that can adjust its stroke length. Lengthening or shortening the stroke and simultaneously extending or retracting the connecting rod's travel distance, allows the internal combustion engine to function very efficiently consequently reducing the free space between the piston and cylinder head at TDC position. This allows the internal combustion engine to alter its power capability on demand whilst maintaining relatively high compression efficiency. The method of altering the stroke length is achieved by manipulating gears situated internally and externally of the engine sub-assembly. The control of these eccentric gears lowers or lifts the crankshaft in a radial motion. The eccentrics also control the automatic extension or retraction of the connecting rod's travel distance. The externally concentric gears control the mechanism that allows the internal combustion engine to change its capacity easily as adapted for automation. This study does not extend into the automation issues of the external mechanism. The prototype engine that was built could not endure vigorous testing and it failed after running for a short while. The primary focus had been on the kinematics of the engine mechanism - and to show whether the idea was feasible. The engine passed the kinematics test but failed possibly due to dynamic loads. Investigating this requires measuring instantaneous temperatures from which peak pressures can be deduced. This was not done because it was outside the scope of the project.

Orientador: Marco Lúcio Bittencourt / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T04:09:11Z (GMT). No. of bitstreams: 1 Rodrigues_AlexdeSouza_M.pdf: 4083435 bytes, checksum: d064f345587c31e235681e0db1417f27 (MD5) Previous issue date: 2013 / Resumo: Devido às atuais exigências de leis de emissão e redução de consumo de combustível, busca-se reduzir o peso dos componentes sem impacto aos critérios de projeto. Neste sentido, torna-se importante entender e discutir os critérios de projeto do componente em estudo. Este trabalho tem por objetivo entender a influência da redução do contrapeso de uma árvore de manivelas quatro cilindros em linha. Assim, para analisar o impacto da redução de massa nos contrapesos, foi realizado um estudo de sensibilidade nesta região do componente. Para analisar esta viabilidade, foram discutidos alguns critérios de balanceamento e a dinâmica do virabrequim em operação no motor. Nestas metodologias de balanceamento, resumiu-se a teoria básica mais comumente utilizada. Neste trabalho, aplicou-se o conjunto de ferramentas analisadas em um estudo de caso para um virabrequim forjado de um motor quatro cilindros em linha, obtendo-se a diferença dos critérios de balanceamento utilizados em relação à análise dinâmica. Foi observado que há critério de balanceamento que não considera efeito dinâmico importante. Finalmente, demonstrou-se que quando se deseja ter um contrapeso leve, existem alternativas de geometria que minimizam o impacto da retirada de massa / Abstract: Due to the current emission standard and fuel consumption requirements, lightweight components with no impact in the design criterion are desired. As a consequence, it is vital to understand and discuss the design criteria of the studied component. This work aims to understand the influence of crankshaft counterweight reduction in an inline-four cylinder engine. Thus, to analyze the counterweight mass reduction, it was done a sensitivity study at this region. In order to analyze this feasibility, it was discussed some balancing criteria and also the crankshaft under virtual engine operation. In these balancing methodologies, it was summarized the basic theory usually designed. In this work, it was applied a package of tools in a study of case for a 4cyl. in-line engine crankshaft, obtaining the difference between some balancing methods versus the dynamics analysis. It was noticed that there are balancing methodologies which do not mind important dynamics effect. All in all, it was showed that if a lightweight design is desired, there are some ways to minimize the unbalancing impact when saving counterweight mass / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientadores: Pablo Siqueira Meirelles, Douglas E. Zampieri / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T03:09:14Z (GMT). No. of bitstreams: 1 Mendes_AlexandreSchalch_M.pdf: 7112696 bytes, checksum: 0f7bdbd014e6bd5c62865524aaa15fca (MD5) Previous issue date: 2005 / Resumo: Este trabalho tem como objetivo a análise do fenômeno das vibrações torcionais em árvores de manivelas de motores de combustão interna para aplicações veiculares. Como exemplo, a formulação proposta será aplicada no estudo da árvore de manivelas de um motor fabricado pela empresa MWM Motores Diesel Ltda., de seis cilindros em linha, quatro tempos, considerando-se a utilização de um amortecedor de vibrações de material elastomérico acoplado ao componente. Da análise das vibrações torcionais é possível de se obter os torques atuantes em cada secção do virabrequim. Estes esforços poderão ser aplicados posteriormente como condições de contorno a um modelo de elementos finitos, para que juntamente aos demais carregamentos existentes, seja feita a verificação do ciclo de fadiga atuante, de modo a avaliar o coeficiente de segurança do componente. Apesar de não ser este o foco deste trabalho, pode-se notar a importância da análise das vibrações torcionais no dimensionamento estrutural de uma árvore de manivelas. Iremos comparar as amplitudes de vibrações torcionais teóricas às obtidas experimentalmente, para a validação do modelo matemático proposto / Abstract: The scope of this work is the study of the crankshaft torsional vibration phenomenon for internal combustion engines. As an example, the formulation will be applied to an engine for a vehicular application, manufactured by MWM Motores Diesel Ltda., with six cylinders in line configuration, four strokes and considering a rubber damper assembled to the component. From the torsional vibrations analysis, it is possible to ca1culatethe actuating torque in each crankshaft section. These loads can be applied as boundary conditions to a finite element model and with the consideration of the other existing loads it is possible to determine the fatigue cyc1e,to calculate the safety factor ofthe component. This is not the objective ofthis work, but it is possible to note the importance of the torsional vibrations analysis in the structural dimensioning of the crankshafts. The obtained results by the presented methodology will be compared to the measured values for the validation of the proposed mathematical model / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Glow plugs are widely used to promote the desired cold start and post-cold start combustion characteristics of light duty diesel engines. The importance of the glow plug becomes more apparent when the compression ratio is low. An experimental investigation of combustion initiation and development aided by the glow plug has been carried out on a single cylinder HPCR DI diesel engine with a low compression ratio of 15.5:1. High speed imaging of combustion initiated by the glow plug in a combustion bomb has been used to add understanding of initiation process. Complementary CFD studies have been carried out using ANSYS Fluent 14.0 to explore the interactions between the glow plug and the spray behavior. Observation of successful combustion initiation show that two conditions must be met, compression heating and heat transfer from the glow plug must raise temperature of gas nearby to at least 413ºC and the vapour/air equivalence ratio no lower than 0.15-0.35. The initiation site was at spray edge close to the glow plug, the flame grew locally before expanding downstream in direction of spray penetration after the end of the main injection. Experimental studies carried out on the engine indicated that the engine IMEP, heat release and combustion stability were continuously improved by using the glow plug at ambient temperatures higher than the temperature requiring the glow plug for initiation of combustion. A rapid development of premixed combustion was achieved associated with improved engine work output, heat release rate and cycle-by-cycle stability. The premixed combustion was enhanced by strengthening spray vaporization through the glow plug. In this study, the combustion behavior was enhanced by the glow plug up to ambient temperature of 20ºC. Initiation delay was shortened by a rapid development of combustion aided by the glow plug. An initiation delay model was developed to account for both physical part (transport delay) and chemical part (chemical delay). The transport delay (ms) is equivalent to the time for spray to transport to the vicinity of the glow plug, dictated by parameters including S, distance between the glow plug tip and the injector tip (mm).

Internal diesel injector deposits (IDIDs) have become a prolific issue in the last decade, increased number of incidences have occurred since the introduction of ultra-low sulfur diesel and biodiesel. The IDIDs have caused concerns for customers such as injector systems misfiring or blocking, increased emissions and fuel consumption. Interest into the origins of the deposits has steadily grown, with identified possible causes including contaminants, degraded additives, or thermal and pressure stresses of the engine. Most examples in previous studies only provide surface analysis of IDIDs, however, the surface only provides a relatively small part of the story. In order to understand how an IDID has formed the history needs to be explained, to do this the lower layers of the IDID need to be analysed. Outcomes of this research include the first example of focused ion beam and secondary ion mass spectrometry being used in combination to analyse IDIDs and clearly shows different chemical layers, demonstrating that these deposits are made up of multiple complex chemistries. Raman spectroscopy can provide graphitic content information for IDIDs giving evidence of formation however, a method to remove fluorescence from carbonaceous structures was first devised and validated in order to allow this to be performed. The jet fuel thermal oxidation test (JFTOT) has been proven to be an effective method of replicating deposits on comparison with IDIDs from failed field engines, and key chemistries have been identified for B20 biodiesel and ultra-low sulfur diesel (ULSD). This work has used existing analytical methods to understand IDIDs and found novel insights that have not been previously observed in the literature.

The study of the reciprocating internal combustion engine is of prime importance to the student engineer. In our present civilization, the number of units and the total rated power of internal combustion engines in use is far greater than that of all other prime movers combined. Many basic engineering problems are present in the study of the operation of internal combustion engines. A number of mechanical and electrical devices have been developed to aid the engineer in his studies of engine performance. The purpose of this project is to provide the Mechanical Engineering Department of the North Dakota State University with an addition to its laboratory facilities which will enable the student to do additional experimental work in the internal combustion engines field. / North Dakota State University (NDSU)

Five plasma jet ignitor designs were tested on a Waukesha ASTM-CFR engine fueled with natural gas. The pollutant emissions, fuel and air flow rates and dynamic cylinder pressure were measured for the full range of Air/Fuel ratios. From these measurements the indicated power and specific fuel consumption were calculated. The energy for the ignitors was provided by a variable high energy ignition system, and each ignitor was supplied with 0.00, 0.08, 0.32, 0.72 and 1.28 Joules of energy in addition to that provided by the standard ignition coil. To differentiate between the benefits gained by use of the plasma jet ignitors and those due to the higher ignition energies, an ordinary spark plug was also tested with added ignition energies. The goal of the experiment was to find an ignitor that could be used to extend the lean operating limit of a natural gas fueled engine, so that the emission of NO_x, and other pollutants could be reduced. The following table shows the optimum pollutant emission reductions achieved by the use of the most effective plasma jet ignitor and the high energy spark plug compared with the emissions from the engine when operated with the standard equipment spark plug near stoichiometric. The plasma jet ignitor for which the results are displayed in this table consisted of an 83 mm³ cavity and a 118 mm³ ejector, both of which were insulated with ceramic cylinders. / Master of Science

Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: In the design or modification of internal combustion (IC) engine components, the South African Automotive industry has always relied on either design by mother companies or quasi-empirical design methods. These methods have restricted the performance and reliability of local designs. A personal computer based model of four stroke engine operation has been developed as a rapid and cost-effective aid to users who wish to determine the performance of an engine with reasonable accuracy before dynamometer testing is possible. This model consists of a thermodynamic model of combustion and gas exchange linked to a manifold flow model. Accompanying this is a simulation of valve flow and a cam dynamic model, enabling full assessment of the optimum cam profiles and valve angles for various automotive engine configurations. The accuracy of these models has been verified by comparison with a set of engine dynamometer tests. The models have also been used with great success in local and international development projects in conjunction with local automotive manufacturers. In particular, two engine upgrade projects have been successfully completed, in which the program was used to aid the design of inlet manifolds, the selection of camshafts, and the selection of compression ratios. / AFRIKAANSE OPSOMMING: In die ontwerp of modifikasie van binnebrandenjin-komponente het die Suid-Afrikaanse Motorbedryf gewoonlik staatgemaak op óf die ontwerpe van die moedermaatskappy óf is van quasi-empiriese ontwerp metodes gebruik gemaak. Hierdie metodes het die werkverrigting en uithouvermoë van plaaslike ontwerpe beperk. 'n Rekenaar model wat die werking van 'n vierslagenjin moduleer, is ontwikkel as 'n vinnige en koste effektiewe hulpmiddel vir ontwerpers om 'n redelike akkurate voorspelling van enjin werkverrigting te verkry, voordat dynamomotor toetswerk moontlik is. Die model bestaan uit 'n termodinamise model vir ontbranding en die gas uitruilproses, gekoppel aan 'n spruitstuk vloeimodel. Die model word saam met 'n simulasie van klepvloei en 'n nok dinamiese model gebruik, wat toelaat dat 'n goeie raming van die optimum nokprofiele en klephoeke gemaak kan word vir verskeie automobielenjin konfigurasies. Die akuraatheid van hierdie modelle is bevestig deur die vergelyking van simulasie resultate met 'n omvangreike stel enjin dynamomotor toetse. Die modelle is ook met groot sukses in verskeie plaaslike en internasionale ontwikkelingsprojekte, in samewerking met die plaaslike motorbedryf, gebruik. In besonder is twee enjinontwikkelingsprojekte suksesvol voltooi, waarin die simulasie program gebruik is om die ontwerp van die inlaat spruitstuk, die keuse van nokasse en die keuse van drukverhouding te vergemaklik.

Thesis. 1979. Ph.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / Ph.D.