Dissertations / Theses: 'Engine performance and combustion characteristics'

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Yang, Changho. "Investigation of combustion and performance characteristics of CAI combustion engine with positive and negative valve overlap." Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/3016.

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In the first part of studies, Controlled Auto-Ignition (CAI) combustion was investigated in a Ricardo E6 single cylinder, four stroke gasoline engine. CAI combustion is achieved by employing positive valve overlap configuration in combination with various compression ratios and intake air temperature strategies. The CAI operational region is limited by engine load due to knock and partial burned boundaries. The combustion characteristics and emissions are studied in order to understand the major advantages and drawbacks of CAI combustion with positive valve overlap. The enlargement of the CAI operational region is obtained by boosting intake air and external EGR. The lean-boosted operation elevators the range of CAI combustion to the higher load region, and the use of external EGR allows the engine to operation with CAI combustion in the mid range of region between boosted and N/A CAI operational range. The results are analyzed and combustion characteristics, performance and emissions are investigated. A Ricardo Hydra single cylinder, four stroke optical gasoline engine with optical access is then experimented to investigate CAI combustion through negative valve overlap configuration and an intake heater. The effects of direct fuel injection timings spark timings and air/fuel ratio are studied by means of simultaneous incylinder heat release study and direct visualization, chemiluminescence techniques which uses full, OH radical and CHO species. Both heat release analysis and chemiluminescence results have identified the pressure of minor combustion during the NVO period. Both the charge cooling and local air/fuel ratio effects are also investigated by varying the quantity of direct air injection.

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Fleck, R. "Predicting the performance characteristics of internal combustion engines." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431397.

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Groenewegen, Jon-Russell Jacob. "The Performance and Emissions Characteristics of Heavy Fuels in a Small, Spark Ignition Engine." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1323369703.

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Pisac, Claudia A. "An experimental study of combustion characteristics of fatty acid methyl ester biodiesel." Thesis, University of Hertfordshire, 2014. http://hdl.handle.net/2299/14641.

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The thesis presents an experimental investigation of combustion performance and emissions of waste cooking oil (WCO) based biodiesel. To evaluate the comparative performance of biodiesel and diesel, combustions tests were conducted using Continuous Combustion rig (CCR) and Land Rover VM diesel engine. Firstly, physical properties of WCO biodiesel and diesel samples were measured in the laboratory. Elemental analysis of WCO biodiesel showed that there are differences between the functional groups in diesel and biodiesel which lead to major differences in the combustion characteristics of the two fuel types. It was found that biodiesel had 10% lower carbon content, almost no sulphur content for biodiesel and up to 12% more oxygen content compared with diesel. This explains the lower caloric value for WCO biodiesel (up to l8 %) compared with diesel. However, higher oxygen content and double bounds in WCO biodiesel increase its susceptibility to oxidation. The CCR test results showed an increase in combustion gas temperature with the increases in biodiesel blend ratio in diesel. This was due to a faster reaction rate for biodiesel than that of diesel leading to a faster brakeage of the hydrocarbon chain to release more heat. The engine tests were performed to measure the torque and emissions for different engine speeds and loads. In general a decrease in engine torque with up to 9% for biodiesel was observed, which was due to the lower calorific value of biodiesel compared with that of diesel. The brake specific fuel consumption (BSFC) increased as the biodiesel blend ratio in diesel increases due a greater mass of fuel being injected at a given injection pressure, compared with diesel. Using WCO blends ratio up to 75% in diesel showed a reduction in exhaust emission compared with diesel, however, at the cost of increased fuel consumption. A common conclusion can be drawn in favour of the WCO biodiesel as being a greener alternative to petro-diesel when used in blend with diesel. However, due to large variations in the biomass used for biodiesel production could lead to variations in physical and chemical properties between biodiesel produced from different biomass. Therefore more stringent standards need to be imposed for biodiesel quality in order to diminish the effect of variation in physicochemical properties on engine performance and emissions. The future work in developing standard test procedures for establishing fuel properties and limits/targets would be beneficial in using a large amount of waste cooking oil in the production of biodiesel, thus contributing to reduction in CO2 and waste minimisation.

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Namasivayam, Ashand Mitra. "Combustion, performance and emissions characteristics of compression-ignition engines fuelled by sustainable fuels." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/668.

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Internal combustion engines are approaching their theoretical maximum efficiency, which could indicate limited future technological improvements in performance and exhaust emissions with standard fuels. In addition, fossil fuel dependence can only be reduced by implementing appropriate renewable fuel sources. The experimental investigation in this work only concerns the compression-ignition (CI) engine combustion process both in normal operation and “dual-fuel” operation. The dual-fuel mode allows low-cetane number fuel to be used in CI engines, with a “pilot” fuel spray injection of high-cetane number fuel to provide ignition. Initially, rapeseed methyl ester (RME) and two water-in-RME emulsions were compared with normal diesel fuel during normal operation. Neat RME generally performed similarly to diesel fuel, while giving higher specific fuel consumption (SFC) levels. Both water- in-RME emulsions performed fairly similarly to neat RME. This suggests that the cooling effect of water vapourisation was a negligible factor throughout the operating range. Natural gas dual-fuel operation reduced NOx at certain conditions and overall CO2 emissions while thermal efficiencies were maintained compared with normal operation. However, significantly higher unburnt hydrocarbons (HC) and CO emissions were recorded at low and intermediate engine loads. For the emulsified pilot fuels, better fuel-air mixing (possibly as a result of “microexplosions”) increased NOx after an equivalence ratio of about 0.6. Hydrogen dual-fuel operation generally increased NOx emissions while CO2 emissions were reduced compared with normal operation. Thermal efficiencies remained comparable for all pilot fuels. NOx emissions in the emulsified fuel cases were generally comparable to the neat RME pilot. Lower volumetric efficiency was also recorded, while power output was limited to maintain engine stability and avoid abnormal combustion caused by excessively high pressure-rise rates (called “hydrogen knock”). Overall, significant optimisation is needed to improve combustion efficiency at low and intermediate engine loads during dual-fuel CI engine operation. As these engines are designed specifically for liquid fuels, substantial engine customisation or even complete redesign (particularly in the fuel supply system) is needed to improve the combustion quality on a scale larger than that seen in this work.

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Martins, Mario Eduardo Santos. "Investigation of performance and characteristics of a multi-cylinder gasoline engine with controlled auto-ignition combustion in naturally aspirated and boosted operation." Thesis, Brunel University, 2007. http://bura.brunel.ac.uk/handle/2438/7915.

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Controlled Auto-Ignition (CAI) also known as Homogeneous Charge Compression Ignition (HCCI) is increasingly seen as a very effective way of lowering both fuel consumption and emissions. Hence, it is regarded as one of the best ways to meet stringent future emissions legislation. It has however, still many problems to overcome, such as limited operating range. This combustion concept was achieved in a production type, 4-cylinder gasoline engine, in two separated tests: naturally aspirated and turbocharged. Very few modifications to the original engine were needed. These consisted basically of a new set of camshafts for the naturally aspirated test and new camshafts plus turbocharger for the boosted test. The first part of investigation shows that naturally aspirated CAI could be readily achieved from 1000 to 3500rpm. The load range, however, decreased noticeably with engine speed due to flow restrictions imposed by the low lift camshafts. Ultra-low levels of NOx emissions and reduced fuel consumption were observed. After baseline experiments with naturally aspirated operation, the capability of turbocharging for extended CAI operation was investigated. The results show that the CAI range could achieve higher load and speed with the addition of the turbocharger. The engine showed increased fuel consumption due to excessive pumping losses. Emissions, however, have been reduced substantially in comparison to the original engine. NOx levels could be reduced by up to 98% when compared to a standard SI production engine.

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Redford, Tim. "Effects of incomplete fuel-air mixing on the performance characteristics of mixed compression, shock-induced combustion ramjet, shcramjet, engines." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0010/MQ34109.pdf.

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Liu, Liang 1971. "Modeling the performance of the piston ring-pack with consideration of non-axisymmetric characteristics of the power cylinder system in internal combustion engines." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30336.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. Includes bibliographical references (p. 139-143). The performance of the piston ring-pack is directly associated with the friction, oil consumption, wear, and blow-by in internal combustion engines. Because of non-axisymmetric characteristics of the power cylinder system, the performance of a ring varies along its circumference. Investigating these variations is of great interest for developing advanced ring-packs, but is out of the capabilities of the existing two-dimensional models. In this work, three separate but closely related numerical models were developed to study the performance of the piston ring-pack. The model for static analysis was developed to facilitate the design of piston rings. In this model, a finite beam element model is adopted with incorporation of a physics-based sub-model describing the interaction between the ring and the bore as well as the ring and the groove. A step-by-step approach is adopted to calculate the ring/bore and ring/groove conformability if the free shape of the ring is given. A method that can be used to determine the free shape as to achieve a specific tension distribution is also developed. Model results revealed the complex ring/bore and ring/groove interaction. A three-dimensional model for ring dynamics and blow-by gas flow was developed to address non-axisymmetric characteristics of the power cylinder system. In this model, the rings are discretized into straight beam elements. 3-D finite element analysis is employed to address the structural response of each ring to external loads. Physics-based sub-models are developed to simulate each ring's interactions with the piston groove and the liner. The gas flows driven by the pressure difference along both the axial and circumferential directions are modeled as well. (cont.) This model predicts the inter-ring gas pressure and 3-D displacements of the three rings at various circumferential locations. Model results show significant variations of the dynamic behavior along ring circumference. In the ring-pack lubrication model, an improved flow continuity algorithm is implemented in the ring/liner hydrodynamic lubrication, and proves to be very practicable. By coupling the ring/liner lubrication with the in-plane structural response of the ring, the lubrication along the entire ring circumference can be calculated. Model results show significant variations of lubrication along the circumference due to the non-axisymmetric characteristics of the power cylinder system. Bore distortion was found to have profound effects on oil transport along the liner. Particularly, it stimulates the occurrence of oil up-scraping by the top ring during compression stroke. Because the oil evaporation on the liner affects the liner oil film thickness, a sub-model for liner evaporation with consideration of multi-species oil is incorporated with the lubrication model. With consideration of oil transport along the liner, the prediction of evaporation is more precise. The combination of these models is a complete package for piston ring-pack analysis. It is computationally robust and efficient, and thus has appreciable practical value. by Liang Liu. Ph.D.

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Gaudart, Louis. "Incidences des configurations de fonctionnement de navires militaires sur la suralimentation a deux etages de leurs moteurs diesel de propulsion pag btc." Nantes, 1987. http://www.theses.fr/1987NANT2061.

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Attard, William. "Small engine performance limits - turbocharging, combustion or design." SAE Technical Paper Series, 2007. http://repository.unimelb.edu.au/10187/514.

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Growing concerns about interruption to oil supply and oil shortages have led to escalating global oil prices. In addition, increased public acceptance of the global warming problem has prompted car manufacturers to agree to carbon emission targets in many regions including most recently, the Californian standards. Other legislating bodies are sure to follow this lead with increasingly stringent targets. As a result of these issues, spark ignition engines in their current form will need significant improvements to meet future requirements. One technically feasible option is smaller capacity downsized engines with enhanced power that could be used in the near term to reduce both carbon emissions and fuel consumption in passenger vehicles.This research focuses on exploring the performance limits of a 0.43 liter spark ignited engine and defining its operating boundaries. Limiting factors such as combustion, gas exchange and component design are investigated to determine if they restrict small engine performance. The research gives direction to the development of smaller gasoline engines and establishes the extent to which they can contribute to future powertrain fuel consumption reduction whilst maintaining engine power at European intermediate class requirements.

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Erickson, Robert R. "A Numerical Investigation on the Influence of Engine Shape and Mixing Processes on Wave Engine Performance." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6819.

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Wave engines are a class of unsteady, air-breathing propulsion devices that use an intermittent combustion process to generate thrust. The inherently simple mechanical design of the wave engine allows for a relatively low cost per unit propulsion system, yet unsatisfactory overall performance has severely limited the development of commercially successful wave engines. The primary objective of this investigation was to develop a more detailed physical understanding of the influence of gas dynamic nonlinearities, unsteady combustion processes, and engine shape on overall wave engine performance. Within this study, several numerical models were developed and applied to wave engines and related applications. The first portion of this investigation examined the influence of duct shape on driven oscillations in acoustic compression devices, which represent a simplified physical system closely related in several ways to the wave engine. A numerical model based on an application of the Galerkin method was developed to simulate large amplitude, one-dimensional acoustic waves driven in closed ducts. Results from this portion of the investigation showed that gas-dynamic nonlinearities significantly influence the properties of driven oscillations by transferring acoustic energy from the fundamental driven mode into higher harmonic modes. The second portion of this investigation presented and analyzed results from a numerical model of wave engine dynamics based on the quasi one-dimensional conservation equations in addition to separate sub-models for mixing and heat release. This model was then used to perform parametric studies of the characteristics of mixing and engine shape. The objectives of these studies were to determine the influence of mixing characteristics and engine shape on overall wave engine performance and to develop insight into the physical processes controlling overall performance trends. Results from this model showed that wave engine performance was strongly dependent on the coupling between the unsteady heat release that drives oscillations in the engine and the characteristics that determine the acoustic properties of the engine such as engine shape and mean property gradients. Simulation results showed that average thrust generation decreased dramatically when the natural acoustic mode frequencies of the engine and the frequency content of the unsteady heat release were not aligned.

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Bonnet, Baptiste. "Matching of Internal Combustion Engine Characteristics for Continuously Variable Transmissions." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/3205.

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This work proposes to match the engine characteristics to the requirements of the Continuously Variable Transmission [CVT] powertrain. The normal process is to pair the transmission to the engine and modify its calibration without considering the full potential to modify the engine. On the one hand continuously variable transmissions offer the possibility to operate the engine closer to its best efficiency. They benefit from the high versatility of the effective speed ratio between the wheel and the engine to match a driver requested power. On the other hand, this concept demands slightly different qualities from the gasoline or diesel engine. For instance, a torque margin is necessary in most cases to allow for engine speed controllability and transients often involve speed and torque together. The necessity for an appropriate engine matching approach to the CVT powertrain is justified in this thesis and supported by a survey of the current engineering trends with particular emphasis on CVT prospects. The trends towards a more integrated powertrain control system are highlighted, as well as the requirements on the engine behaviour itself. Two separate research axes are taken to investigate low Brake Specific Fuel Consumption [BSFC] in the low speed region and torque transient respectively for a large V8 gasoline engine and a turbocharged diesel V6 engine. This work is based on suitable simulation environments established for both engines in the powertrain. The modelling exercises are aimed at supplying appropriate models that can be validated against experimental data. The simulation platforms developed then allow the investigation of CVT powertrain biased engine characteristics. The V8 engine model in particular benefited from engine and vehicle dynamometer data to validate the model behaviour and the accuracy of the prediction. It benefited from the parallel work conducted on the Electrically Assisted Infinitely Variable Transmission [EASIVT] project in Cranfield University. The EASIVT vehicle is a parallel mild hybrid aimed at demonstrating the combined fuel economy benefits of a CVT technology and hybridisation. From the CVT powertrain requirements for fuel economy, BSFC operation can be further promoted in the low speed region if Noise Vibration and Harshness [NVH] counter-measures are developed. A study of the combustion torque oscillations at the crankshaft led to the elaboration of an Active Vibration Control [AVC] strategy for the hybrid Integrated Motor Generator [IMG]. Successful implementation of the strategy in both simulation and in-vehicle helped quantify the benefits and short comings of engine operation for best fuel economy. The development in parallel of the hybrid control functions for torque assist and regenerative braking made it possible to implement the low speed AVC in the vehicle without a driveability penalty. The V6 TDI model yielded a realistic and representative simulation for the transient torque response improvement research to be undertaken. For that purpose, the model was tuned against full-load data and the air path control sub-systems were designed and calibrated similarly to a real application. The model was able to highlight the turbocharger lag issue associated with a large combined speed and torque transient inevitable in the fuel economy biased CVT powertrain. This study proposes a Manifold Air Injection [MAI] system in the intake of the engine to help breathing when the VGT operating conditions cannot be shifted rapidly enough for a manoeuvre. The system design constraints were analysed and a suitable strategy was elaborated and calibrated. A sensitivity analysis was also conducted to demonstrate the influence of the MAI design and control variables on the engine performance in the CVT powertrain In conclusion, the benefits of the engine characteristic matching were highlighted in both cases. A review of the work achieved is available in the last chapter, including prospects for further improvements and investigations. The ideal engine characteristics for gasoline and diesel engine technologies integrated in a CVT powertrain are derived from the experience gathered in the research and the results obtained from the tests in low speed operation and transient torque control respectively for the gasoline and the diesel engines. The engine characteristics can be altered toward a better match with a CVT by the use of specific hardware and control strategy. This work recommends that a direct injected, variable valve actuated gasoline engine provides the ideal starting point for low fuel consumption powertrain. When integrated within a mild hybrid CVT powertrain, the full benefits are obtained with the use of low speed operation and AVC. If no electrical machine is available to torque assist the engine, then existing supercharging concepts for a downsized engine can be applied. Diesel engines can also be downsized because of their high torque density. Increased turbocharging boost levels allow steady state torque levels to be maintained in the downsizing process. The CVT powertrain can optimise the fuel consumption and emission levels by appropriate selection of the engine steady state operating points. The torque response lag then becomes critical for the CVT to control the engine speed. This can be improved by the use of Manifold air Injection to assist the turbocharger.

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Thomas, François. "Contribution a l'etude des performances d'une petite turbine de suralimentation en regime stationnaire." Paris, ENSAM, 1987. http://www.theses.fr/1987ENAM0015.

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Etude d'une turbine radiale de turbocompresseur de suralimentation de moteur. Le calcul est base sur la resolution de l'equation de l'equilibre radial dans la section de sortie de la machine. On se limite a une approche monodimensionnelle de l'ecoulement. Etablissement experimental d'une cartographie des ecarts flux-profil en sortie de roue

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Dawood, Alaa Eldin Elsaeed Shafeek. "Combustion and flow characteristics in a disc-shaped spark ignition engine." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535686.

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Taylor, Oliver. "Improving the performance of internal combustion engines through lubricant engineering." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:4db8f32e-8260-4cff-ad57-08bfa0b9568e.

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Low friction lubricant development provides a worthwhile contribution to vehicle CO2 emission reduction. Conventional low friction lubricant development focuses on empirical processes using out dated engine technology and old test methods. This strategy is inefficient and restricts the lubricant's potential. A new method proposed in the present research combines tribological simulations with rig, engine and vehicle tests. This approach provides insights undocumented until now. The contribution to CO2 emission reduction from individual engine components on vehicle drive cycles that include warm-up is predicted using lubricants down to the new SAE 8 viscosity grade. A bearing model is used to design the lubricant's non Newtonian characteristics to achieve friction reduction. An isoviscous lubricant with a viscosity of 4.6 cSt is shown to achieve the minimum friction in the bearing. The research shows that by starting with lubricants having kinematic viscosities higher than this value, it is possible to improve lubricant performance by lowering viscosity index (VI), introducing shear thinning, or reducing the density and pressure viscosity coefficient. Conversely, for lubricants with lower starting viscosities it is shown that higher VI values, more shear-stable lubricants and higher densities and pressure viscosity coefficients are required. The model predicts that high oil film pressures occur in the bearing and cause significant local lubricant viscosity increase (300&percnt;), indicating that the lubricant's pressure viscosity behaviour is important here, despite the contact being conformal. Simulation and motored engine testing establishes lubricant behaviour in the piston-to-bore conjunction. This analysis identifies a poor correlation between measured and predicted values at low engine speeds. A rig-on-liner tribometer shows that this error is attributable to a deficiency in the simulation's characterisation of boundary regime friction. An oil pump test determines how a modern variable displacement oil pump (and its control system) responds to lowering viscosity. The hypothesis that low viscosity lubricants cause the parasitic load from this component to increase is disproven using this component-level rig test. Chassis dynamometer testing compares the CO2 reduction performance of lubricant thermal management systems to the values achieved by reducing the viscosity grade. CO2 reductions of between 0.4&percnt; and 1.0&percnt; are identified using a cold-start new European drive cycle (NEDC) with a 5W-30 preheated to 60°C and 90°C respectively. Reductions in CO2 emissions between 0.4&percnt; and 1.2&percnt; are found on the NEDC by lowering the oil fill volume from 5.1 L to 2.1 L. For the unmodified case, a 3.7&percnt; reduction in CO2 emissions is reported by reducing the viscosity grade from a 5W 30 to an SAE 8 in the NEDC. The performance of a novel external oil reservoir is simulated to understand its ability to retain oil temperature during the vehicle cool-down procedure. An oil temperature of 65°C at the end of the soak period (following a prior test where the oil was assumed to reach 90°C) is predicted by installing insulation to the reservoir and indicates that a viable method to achieve the CO2 benefits identified through lubricant preheating tests exists. A full vehicle model combines the outputs from each of these sub-models to predict lubricant performance on the NEDC the new World-wide harmonized light duty test cycle (WLTC). This new approach provides a tool that enables next generation low friction lubricants to be developed. The model predicts that an SAE 8 lubricant can reduce CO2 emissions by 2.8&percnt; on the NEDC and 1.9&percnt; on the WLTC compared to a 5W-30. A theoretical experiment, where all lubricant related friction was deleted from the simulation, predicts that lubricant-related CO2 emissions are 8.7&percnt; on the NEDC and reduce to 6.3&percnt; on the WLTC. These results indicate that the planned adoption of the WLTC in September 2017 reduces the potential contribution to CO2 emission reduction from lubricants by 28&percnt;.

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Seabrook, Justin Frank. "Combustion and emissions optimisation in a high performance S.I. engine." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362422.

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VILLELA, ANTONIO CARLOS SCARDINI. "ANHYDROUS AND HYDROUS ETHANOL PERFORMANCE AND COMBUSTION IN MULTIFUEL ENGINE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16728@1.

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PETRÓLEO BRASILEIRO S. A. O presente trabalho apresenta um estudo comparativo do desempenho, em banco de provas, de um motor multicombustível do ciclo Otto equipado com um sistema de injeção eletrônica programável, funcionando com etanol hidratado e etanol anidro. Para tanto, foram obtidos resultados de parâmetros de desempenho com esses dois combustíveis, em diferentes condições de operação. A partir dos resultados de pressão, adquiridos por um sensor instalado em um dos cilindros do motor, foram calculados, entre outros, o calor liberado, a taxa de liberação de calor, a fração de massa queimada e a duração da combustão. Os ensaios ocorreram em três condições operacionais do motor multicombustível: potência máxima, torque máximo e em uma condição representativa de velocidade de cruzeiro do motor. Devido à possibilidade de se variar livremente alguns parâmetros normalmente fixos em um motor com um sistema de injeção eletrônica de combustível convencional foi possível otimizar o torque do motor para cada combustível e nas condições operacionais escolhidas, no que se refere ao avanço de ignição e à relação ar-combustível. Dessa forma, pôde-se simular os efeitos da utilização do etanol anidro em motor calibrado para o etanol hidratado. Os resultados mostram os efeitos da variação do conteúdo de água no etanol, bem como a influência da relação ar-combustível e do avanço de ignição sobre o desempenho e a combustão em motor multicombustível. São apresentadas ainda correlações entre as variáveis de desempenho medidas e os parâmetros de combustão calculados, bem como comparações com resultados de desempenho obtidos em veículos multicombustível. The present work includes a comparative performance engine test bed study of a multifuel engine equipped with a programmable electronic central unit (ECU), fueled with anhydrous and hydrous ethanol. It is reported fuel consumption, power, torque and exhaust emissions with these two fuels for different operational points. Using pressure data, acquired by a sensor installed in one engine cylinder, it was possible to calculate heat release, rate of heat release, mass fraction burned, combustion duration and others, for selected cases. Tests occurred at three multifuel engine operational points: maximum power, maximum torque and one selected cruise condition. Due to the possibility of setting some parameters normally fixed in commercial engines, torque was optimized regarding spark advance and air fuel ratio, for all selected operational points. So, it was possible to simulate anhydrous ethanol usage in an engine calibrated to hydrous ethanol. Test results presented the effects of water ethanol content, air-fuel ratio and ignition advance influence on performance and combustion of a multifuel engine. Additionally, it is presented some correlations between performance measured and calculated and combustion parameters, as well as comparisons to multifuel vehicle results.

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Tsakiroglou, G. B. "Performance modelling of a one-stroke rotary internal combustion engine." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/848135/.

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The subject of this Thesis is the performance modelling and evaluation of the Rotary Internal Combustion One-Stroke Engine specified in Patent Application number PCT/GB 84/0048. A mathematical model, capable of simulating the various changes that take place during the cycle of the engine, has been formed and applied to the engine for testing its performance. Before forming the model the dimensions of the engine were calculated by considering the stressing of the main movable parts of the engine such as the driveshaft, radial sealing wall and rotary piston, as well as the surface area to volume ratio. Also the timing and conditions under which the engine operates were speci--fied and used as input to the model. The model incorporates six subroutines namely, "DATUM" which stores all the input constants and variables, "GEOMETRY" which calculates various geometrical engine parameters, "COMBUST" and "EXPAND" which simulate the ignition delay/combustion and expansion respectively, and "PERFORMANCE" which calculates the various performance parameters of the engine. The above model was run with different sets of fuel-air ratios/speeds as input. The performance evaluated has been tabulated and a performance map of the engine drawn. Typical pressure-volume and heat flux diagrams were plotted. Further, the model was tested, with different sets of operating variables as input, to optimise the principal dimensions and timing of the engine. The model was validated by adaption to simulate a two-stroke internal combustion reciprocating piston engine and run with MAN-B&W L55GB engine data. The output was compared with the figures quoted by the engine manufacturers. The comparison was favourable. Once the model had been validated a direct comparison was made between the internal combustion rotary one-stroke engine and the MAN-B&W L55GB engine. Costs were analysed and proposals of possible methods of optimising the design of the above engine formulated.

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Mägi, M. "Effect of gasoline fuel additives on combustion and engine performance." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1462024/.

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Ever increasing emissions regulations and demand for fuel economy have brought about great advances in fuel and engine technologies. Improving engine efficiency through the use of fuel additives has been practiced for nearly a century but advances to direct injection gasoline engines have presented new obstacles that need to be overcome. With direct injection systems often suffering from reduced timescales allowed for combustion processes, atomisation and vaporisation characteristics have become of paramount significance. Present study aimed at adding to the field of knowledge by experimentally investigating commercial fuel additives of different functional iti es against their effects on fuel atomisation and combustion characteristics. Fuel atomisation was evaluated through the use of a laser diffraction system and measurement of fuel viscosity and surface tension. Additives from six functional groups were investigated. Additionally, effects of anti-knock and ignition promoting additives on gasoline combustion behaviour were studied in a constant volume combustion vessel and a single cylinder research engine. Flame speed, heat release rate and emissions output were compared for three commercially available combustion improvers. Investigation into the effect of fuel additives on the physical properties and therefore on fuel atomisation and sprays revealed that in commercially employed quantities, no significant change in recorded Sauter Mean Diameter could be observed. Combustion investigations in a combustion vessel demonstrated that the low temperature reactions initiated by ignition promoting additive reduced CO emissions up to 37.7 % which could be attributed to possible reduced flame quenching near combustion chamber walls. However, in high quantities this reduction in CO levels was not experienced. Addition of anti-knock additives resulted in increased NOx emissions, which was thought to result from increased combustion durations. Present work has clarified fuel additive function and interactions with combustion processes and has demonstrated that gasoline fuel additives do not interfere with combustion processes outside their intended functionality.

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Bennett, Matthew James. "Investigation of the flow characteristics in the spark initiation region of SI engines using hot wire and laser doppler anemometry." Thesis, Coventry University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328948.

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Gidney, Jeremy. "The performance stability of a homogeneous charge lean-burn spark-ignition engine." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303644.

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Kevric, Arman. "Combustion characteristics of a compression ignition engine running on biodiesel and gasoline blended fuels." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605993.

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An experimental investigation of the effects of fuel composition on the ignition delay and heat release characteristics of a light duty, automotive compression ignition engine has been carried out. The ignition delay is defined as the period between the start of the main fuel injection event and the start of combustion (SOC). The research has covered a range of fuel types and blends to maximise the effects of composition on the ignition delay and heat release. The fuels used were diesel, gasoline and FAME (Fatty Acid Methyl Esters) produced from rapeseed oil, coconut oil and waste cooking oil. All the engine test studies were carried out using a 2.4 litre displacement, direct injection Ford Puma engine, at test conditions representing low load, mid load and high load at 2000rpm, with EGR rates of up to 35%. Single equation, semi-empirical ignition delay models based upon the Arrhenius equation were studied and developed to fit the experimental ignition delay data, and thus incorporate fuel composition effects. Fuel composition is shown to affect the duration of the ignition delay, but after the start of combustion the heat release characteristics, for a given energy supplied in fuel, proved to be relatively insensitive to fuel composition effects. The premixed fraction is shown to be directly proportional to the ignition delay. The ignition delay of biodiesel fuel is up to 15% shorter than diesel while a gasoline blend of 50% gasoline/50% diesel lengthens the ignition delay by up to 30% with respect to diesel. These differences in the ignition delay affect the engine thermal efficiency by up to 2% due to combustion phasing effects. Gasoline fuel blended up to 80% (by volume) with diesel was combusted successfully, resembling PCCI (Premixed Charged Compression Ignition) combustion regimes, while biodiesel fuel types RME (Rapeseed Methyl Esters), CME (Coconut Methyl Esters) and WCO (Waste Cooking Oil Methyl Esters) all showed differences in heat release characteristics due to ignition delay differences. Calibration changes are necessary to compensate for the fuel composition effects on the ignition delay and subsequent combustion characteristics. An engine specific, single equation ignition delay model was developed that successfully described the experimental ignition delay data over the fuel range of fuel composition: rID = 4.32p-l.02/'P-O.2exp (:;) where EA = A.Kevric University of Nottingham , ' )t8186 . Based upon the analysis of combustion characteristics of the experimental CN+ZS) data, the initial form of a universal ignition delay model was developed, composing of a physical delay portion and a chemical delay portion. A.

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23

Reiter, Aaron Jesse. "Combustion and emissions characteristics of a compression-ignition engine using dual ammonia-diesel fuel." [Ames, Iowa : Iowa State University], 2009.

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24

Wittmers, Nicole K. "Direct-connect performance evaluation of a valveless pulse detonation engine." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FWittmers.pdf.

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25

Behrens, Justin William. "Modification and Performance Evaluation of a Mono-valve Engine." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/638.

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AN ABSTRACT OF THE THESIS OF Justin W. Behrens, for the Master of Science degree in Mechanical Engineering, presented on June 24, 2011 at Southern Illinois University Carbondale. TITLE: MODIFICATION AND PERFORMANCE EVALUATION OF A MONO-VALVE ENGINE MAJOR PROFESSOR: Dr. Suri Rajan A four-stroke engine utilizing one tappet valve for both the intake and exhaust gas exchange processes has been built and evaluated. The engine operates under its own power, but has a reduced power capacity than the conventional 2-valve engine. The reduction in power is traced to higher than expected amounts of exhaust gases flowing back into the intake system. Design changes to the cylinder head will fix the back flow problems, but the future capacity of mono-valve engine technology cannot be estimated. The back flow of exhaust gases increases the exhaust gas recirculation (EGR) rate and deteriorates combustion. Intake pressure data shows the mono-valve engine requires an advanced intake valve closing (IVC) time to prevent back flow of charge air. A single actuation camshaft with advanced IVC was tested in the mono-valve engine, and was found to improve exhaust scavenging at TDC and nearly eliminated all charge air back flow at IVC. The optimum IVC timing is shown to be approximately 30 crank angle degrees after BDC. The mono-valve cylinder head utilizes a rotary valve positioned above the tappet valve. The open spaces inside the rotary valve and between the rotary valve and tappet valve represent a common volume that needs to be reduced in order to reduce the base EGR rate. Multiple rotary valve configurations were tested, and the size of the common volume was found to have no effect on back flow but a direct effect on the EGR rate and engine performance. The position of the rotary valve with respect to crank angle has a direct effect on the scavenging process. Optimum scavenging occurs when the intake port is opened just after TDC.

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26

Aksu, Cagdas. "Performance Analysis Of A Compression Ignition Internal Combustion Engine Using Superheated Ethanol Vapor." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613255/index.pdf.

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The aim of this study is to experimentally measure performance characteristics of a compression ignition (CI) internal combustion engine using superheated ethanol vapor. The engine is a 1.3L inline 4 cylinder direct injection (DI) turbocharged compression ignition (CI) engine. While the engine will be fed with superheated ethanol as homogeneous fuel-air mixture through intake manifold, the amount of diesel fuel that the engine requires to run at idle will also be supplied in order to initiate combustion. Ethanol will be superheated using a new patented double heat exchanger has been manufactured by Prof. Dr. Demir Bayka, Dr. Anil Karel and Deniz &Ccedil akar. The results will indicate if the suggested concept can be applicable.

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27

Daniel, Ritchie Lewis. "Combustion and emissions performance of oxygenated fuels in a modern spark ignition engine." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3675/.

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The combustion and emissions performance of oxygenated fuels has been investigated in a modern direct-injection spark-ignition (DISI) engine. In particular, the new biofuel candidate, 2,5-dimethylfuran, otherwise known as DMF, has been assessed as a future automotive fuel against ethanol, the most commercially accepted spark-ignition (SI) biofuel. When operating with DMF, the engine performance and emissions are less sensitive to changes in key control parameters than with gasoline. This allows a wider window for improving performance and/or reducing emissions. The relevance of modern injection strategies to increase performance or efficiency has also been assessed when using DMF. The use of split-injection at full load is shown to be less beneficial than with gasoline. Novel fuel preparation techniques have been investigated by comparing externally supplied gasoline-biofuel blends (conventional method) to internally mixed, dual-injection blends. This new mode presents an avenue for optimising oxygenated fuels with a low heat of vaporization, such as DMF and n-butanol; low blends with gasoline (≤25% by volume) are more efficiently utilised than in external blends. Furthermore, the particulate matter (PM) emissions can be reduced with dual-injection because gasoline is supplied through PFI. The unlegislated emissions when using DMF have been benchmarked against gasoline and compared to other oxygenated fuels. In particular, the emissions of the major carbonyls are lower when using DMF compared to gasoline and even less so than ethanol, which heavily emits acetaldehyde and formaldehyde. The dual-injection mode further reduces the total carbonyl emissions when using DMF and ethanol blends compared to direct-injection (DI).

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28

McGhee, Michael James. "Factors influencing cycle-by-cycle combustion characteristics of a diesel engine under cold idling conditions." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13179/.

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An experimental investigation of post-start cold idling behaviour has been carried out on a modern single-cylinder HPCR DI light duty diesel engine with a low compression ratio of 15.5:1 at temperatures between 10 and -20°C. The trend toward lower compression ratios from more common values of around 22:1 a few years ago has resulted in lower compression pressures and temperatures, which negatively affects cold idle operation. Improvements in cycle-by-cycle stability of indicated work output through fuel injection strategy and glow plug temperature changes have been explored. This is important to improve NVH and the consumer’s perception of vehicle quality. The key effects on heat release characteristics have been identified and the associated impact on stability discussed. High speed imaging of ignition in a combustion bomb has been used to aid interpretation of engine results. Up to four pilot injections placed in advance of the main have been used. Shorter separation between pilots and pilot-to-main improves stability independent of the number of pilot injections and extends the range of main injection timings to meet target stability of 10% or lower at -20°C. Increasing the number of pilot injections was effective in stabilising combustion at all investigated soak temperatures at fuelling levels producing indicated work required to match friction and ancillary demands. Stability can be susceptible to deterioration at moderate soak temperatures because fuelling demand is relatively low. If a high number of pilot injections are to be avoided to reduce potential wear, then increasing main injection quantity is an effective method to stabilise combustion for a lower pilot number strategy but any increase above target load has to be harnessed by additional ancillary devices. Very high glow plug temperatures of up to 1200°C were examined using a smaller diameter tip ceramic type design. Stable combustion cannot be achieved through higher glow plug temperatures alone. A temperature of 1000°C, which can be achieved using a low voltage metallic type, is adequate to stabilise combustion when combined with a triple-pilot strategy at sub-zero temperatures. The best stability is achieved using 1200°C, which can only be achieved using a more expensive ceramic type, in combination with a triple-pilot strategy producing the desirable target of ~5% or below; the effects are not mutually exclusive. At high glow plug temperatures and using three or four pilot injections, stability improved with warmer soak temperatures. At -5°C, stability was relatively poor when one or two pilots were used irrespective of glow plug temperature. A high premixed contribution to main combustion is associated with improved stability. Minimum threshold values are necessary to stabilise combustion: ~25 J/° at -20°C, ~20 J/° at -5°C and only ~10 J/° at 10°C. A higher number of pilot injections raises pilot induced combustion and improves mixture distribution. These effects subsequently increase the premixed combustion and help sustain a strong main development with less variability. This benefit is maximised when using hotter glow plug temperatures raising IMEPg magnitude and reducing variation.

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He, Yuesheng. "Effect of intake primary runner blockages on combustion characteristics and emissions in spark ignition engines." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1190053207.

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30

Shrestha, Amit. "Development and Performance Evaluation of a Mono-Valve Engine." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1879983291&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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31

Kawambwa, S. J. M. "Performance and combustion of ethanol in a high-compression, direct-injection, compression-ignition engine." Thesis, University of Surrey, 1993. http://epubs.surrey.ac.uk/981/.

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32

Mobasheri, Raouf. "Investigations of advanced injection and combustion strategies on DI diesel engine performance and emissions." Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/43294/.

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The main driving force behind this research was the need for cleaner and more efficient engines to meet the ever-increasing demands on the modern automobile's emissions. In recent years different studies have been carried out to analyze the combined effects of high-pressure injection, boost pressure, multiple injections, included spray angle and combustion chamber geometry. Though considerable research has shown these technologies can meet the low emission regulations, the careful optimization of the engine operating conditions is still required in order to get the full benefit of the different strategies. With these issues as motivation, the first important objective of this study was to gain a detailed understanding of the mechanisms through which fuel injection interacts with other engine parameters and influences diesel combustion and emissions, and hence to attempt to generalize the adoption of multiple injection strategies with regards to improving diesel engine performance. For this purpose, a modified parameter called “Homogeneity Factor of in-cylinder charge” (HF) was introduced and proposed as a new measure in combustion theory to analyze the combustion characteristics and air-fuel mixing process of diesel engines in more detail. The second part of this research builds upon a detail investigation on the included spray cone angle concept and explores further their use in conjunction with multiple-injection strategies in diesel engines. In addition, an investigation was performed in third phase of this research to analyze the effects of piston geometry on combustion, performance and exhaust emission characteristics. The results showed that employing a post-injection combined with a pilot injection results in reduced soot formation from diffusion combustion and enhances the soot oxidation process during the expansion stroke, resulting in decreased soot emissions, while the NOx concentration is maintained in low levels. It was also found that spray targeting is very effective for controlling the in-cylinder mixture distributions especially when it accompanied with advanced injection strategies. Moreover, the results confirmed that a narrower width of piston bowl has a higher unburned fuel air mixture region and hence results in higher soot emissions but with slightly larger piston surface area the optimum operating point could be obtained.

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33

Chiu, Ya-Tien. "A Performance Study of a Super-cruise Engine with Isothermal Combustion inside the Turbine." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/30202.

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Current thinking on the best propulsion system for a next-generation supersonic cruising (Mach 2 to Mach 4) aircraft is a mixed-flow turbofan engine with afterburner. This study investigates the performance increase of a turbofan engine through the use of isothermal combustion inside the high-pressure turbine (High-Pressure Turburner, HPTB) as an alternative form of thrust augmentation. A cycle analysis computer program is developed for accurate prediction of the engine performance and a supersonic transport cruising at Mach 2 at 60,000 ft is used to demonstrate the merit of using a turburner. When assuming no increase in turbine cooling flow is needed, the engine with HPTB could provide either 7.7% increase in cruise range or a 41% reduction in engine mass flow when compared to a traditional turbofan engine providing the sane thrust. If the required cooling flow in the turbine is almost doubled, the new engine with HPTB could still provide a 4.6% increase in range or 33% reduction in engine mass flow. In fact, the results also show that the degradation of engine performance because of increased cooling flow in a turburner is less than half of the degradation of engine performance because of increased cooling flow in a regular turbine. Therefore, a turbofan engine with HPTB will still easily out-perform a traditional turbofan when even more cooling than currently assumed is introduced. Closer examination of the simulation results in off-design regimes also shows that the new engine not only satisfies the thrust and efficiency requirement at the design cruise point, but also provides enough thrust and comparable or better efficiency in all other flight regimes such as transonic acceleration and take-off. Another finding is that the off-design bypass ratio of the new engine increases slower than a regular turbofan as the aircraft flies higher and faster. This behavior enables the new engine to maintain higher thrust over a larger flight envelope, crucial in developing faster air-breathing aircraft for the future. As a result, an engine with HPTB provides significant benefit both at the design point and in the off-design regimes, allowing smaller and more efficient engines for supersonic aircraft to be realized. Ph. D.

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Chiu, Ya-tien. "A Performance Study of a Super-cruise Engine with Isothermal Combustion inside the Turbine." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/30202.

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Current thinking on the best propulsion system for a next-generation supersonic cruising (Mach 2 to Mach 4) aircraft is a mixed-flow turbofan engine with afterburner. This study investigates the performance increase of a turbofan engine through the use of isothermal combustion inside the high-pressure turbine (High-Pressure Turburner, HPTB) as an alternative form of thrust augmentation. A cycle analysis computer program is developed for accurate prediction of the engine performance and a supersonic transport cruising at Mach 2 at 60,000 ft is used to demonstrate the merit of using a turburner. When assuming no increase in turbine cooling flow is needed, the engine with HPTB could provide either 7.7% increase in cruise range or a 41% reduction in engine mass flow when compared to a traditional turbofan engine providing the sane thrust. If the required cooling flow in the turbine is almost doubled, the new engine with HPTB could still provide a 4.6% increase in range or 33% reduction in engine mass flow. In fact, the results also show that the degradation of engine performance because of increased cooling flow in a turburner is less than half of the degradation of engine performance because of increased cooling flow in a regular turbine. Therefore, a turbofan engine with HPTB will still easily out-perform a traditional turbofan when even more cooling than currently assumed is introduced. Closer examination of the simulation results in off-design regimes also shows that the new engine not only satisfies the thrust and efficiency requirement at the design cruise point, but also provides enough thrust and comparable or better efficiency in all other flight regimes such as transonic acceleration and take-off. Another finding is that the off-design bypass ratio of the new engine increases slower than a regular turbofan as the aircraft flies higher and faster. This behavior enables the new engine to maintain higher thrust over a larger flight envelope, crucial in developing faster air-breathing aircraft for the future. As a result, an engine with HPTB provides significant benefit both at the design point and in the off-design regimes, allowing smaller and more efficient engines for supersonic aircraft to be realized. Ph. D.

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35

Aivaz, Balian Razmik. "The effect of compression ratio on the performance of a direct injection diesel engine." Thesis, Brunel University, 1990. http://bura.brunel.ac.uk/handle/2438/11249.

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This thesis considers the effect of compression ratio on the performance of a direct injection diesel engine. One aspect of engine performance is considered in great detail, namely the combustion performance at increased clearance volume. This aspect was of particular interest because variable compression ratio (VCR) systems normally operate by varying the clearance volume. The investigation relied upon results obtained both from experimental and computer simulating models. The experimental tests were carried out using a single-cylinder direct-injection diesel engine, under simulated turbocharged conditions at a reduced compression ratio. A number of one-dimensional computer models were developed; these simulate the induction and compression strokes, and the fuel spray trajectories in the presence of air swirl. The major objectives of the investigation were: to assess the benefits of VCR in terms of improvements in output power and fuel economy; to assess the effects on combustion of increased clearance volume, and investigate methods for ameliorating resulting problems; develop computational models which could aid understanding of the combustion process under varying clearance volume conditions. It was concluded that at the reduced compression ratio of 12.9:1 (compared to the standard value of 17.4:1 for the naturally-aspirated engine), brake mean effective pressure (BMEP) could be increased by more than 50%, and the brake specific fuel consumption (BSFC) could be reduced by more than 20%. These improvements were achieved without the maximum cylinder pressure or engine temperatures exceeding the highest values for the standard engine. Combustion performance deteriorated markedly, but certain modifications to the injection system proved successful in ameliorating the problems. These included: increase in the number of injector nozzle holes from 3 to 4, increase in injection rate by about 28%, advancing injection timing by about 6°CA. In addition, operation with weaker air fuel ratio, in the range of 30 to 40:1 reduced smoke emissions and improved BSFC. Use of intercooling under VCR conditions provided only modest gains in performance. The NO emission was found to be insensitive to engine operating conditions (fixed compression ratio of 12.9:1), as long as the peak cylinder pressure was maintained constant. Engine test results were used in order to assess the accuracy of four published correlations for predicting ignition delay. The best prediction of ignition delay with these correlations deviated by up to 50% from the measured values. The computer simulation models provided useful insights into the fuel distribution within the engine cylinder. It also became possible to quantify the interaction between the swirling air and the fuel sprays, using two parameters: the crosswind and impingement velocities of the fuel spray when it impinges on the piston-bowl walls. Tentative trends were identified which showed that high crosswind velocity coincided with lower smoke emissions and lower BSFC.

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36

Aghaali, Habib. "On-Engine Turbocharger Performance Considering Heat Transfer." Licentiate thesis, KTH, Maskinkonstruktion (Inst.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93981.

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Heat transfer plays an important role in affecting an on-engine turbocharger performance. However, it is normally not taken into account for turbocharged engine simulations. Generally, an engine simulation based on one-dimensional gas dynamics uses turbocharger performance maps which are measured without quantifying and qualifying the heat transfer, regardless of the fact that they are measured on the hot-flow or cold-flow gas-stand. Since heat transfer situations vary for on-engine turbochargers, the maps have to be shifted and corrected in the 1-D engine simulation, which mass and efficiency multipliers usually do for both the turbine and the compressor. The multipliers change the maps and are often different for every load point. Particularly, the efficiency multiplier is different for every heat transfer situation on the turbocharger. The heat transfer leads to a deviation from turbocharger performance maps, and increased complexity of the turbocharged engine simulation. Turbochargers operate under different heat transfer situations while they are installed on the engines. The main objectives of this thesis are: heat transfer modeling of a turbocharger to quantify and qualify heat transfer mechanisms, improving turbocharged engine simulation by including heat transfer in the turbocharger, assessing the use of two different turbocharger performance maps concerning the heat transfer situation (cold-measured and hot-measured turbocharger performance maps) in the simulation of a measured turbocharged engine, prediction of turbocharger walls’ temperatures and their effects on the turbocharger performance on different heat transfer situations. Experimental investigation has been performed on a water-oil-cooled turbocharger, which was installed on a 2-liter GDI engine for different load points of the engine and different heat transfer situations on the turbocharger by using insulators, an extra cooling fan, radiation shields and water-cooling settings. In addition, several thermocouples have been used on accessible surfaces of the turbocharger to calculate external heat transfers. Based on the heat transfer analysis of the turbocharger, the internal heat transfer from the bearing housing to the compressor significantly affects the compressor. However, the internal heat transfer from the turbine to the bearing housing and the external heat transfer of the turbine housing mainly influence the turbine. The external heat transfers of the compressor housing and the bearing housing, and the frictional power do not play an important role in the heat transfer analysis of the turbocharger. The effect of the extra cooling fan on the energy balance of the turbocharger is significant. However, the effect of the water is more significant on the external heat transfer of the bearing housing and the internal heat transfer from the bearing housing to the compressor. It seems the radiation shield between the turbine and the compressor has no significant effect on the energy balance of the turbocharger. The present study shows that the heat transfer in the turbocharger is very crucial to take into account in the engine simulations. This improves simulation predictability in terms of getting the compressor efficiency multiplier equal to one and turbine efficiency multiplier closer to one, and achieving turbine outlet temperature close to the measurement. Moreover, the compressor outlet temperature becomes equal to the measurement without correcting the map. The heat transfer situation during the measurement of the turbocharger performance influences the amount of simulated heat flow to the compressor. The heat transfer situation may be defined by the turbine inlet temperature, oil heat flux and water heat flux. However, the heat transfer situation on the turbine makes a difference on the required turbine efficiency multiplier, rather than the amount of turbine heat flow. It seems the turbine heat flow is a stronger function of available energy into the turbine. Of great interest is the fact that different heat situations on the turbocharger do not considerably influence the pressure ratio of the compressor. The turbine and compressor efficiencies are the most important parameters that are affected by that. The component temperatures of the turbocharger influence the working fluid temperatures. Additionally, the turbocharger wall temperatures are predictable from the experiment. This prediction enables increased precision in engine simulations for future works in transient operations. QC 20120504

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37

Gambrill, Richard. "The sensitivity of diesel engine performance to fuel injection parameters at various operating points." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/11253/.

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This thesis describes research undertaken to establish the advantages and disadvantages of using high pressure common rail fuel injection systems with multiple injection capabilities. The areas covered are detailed as follows. Oscillations in the rail pressure due to the opening of the injector can affect the quantity of fuel injected in subsequent injection events. The source of these oscillations has been investigated. A method of damping or reducing the oscillations has been defined and was applied. This successfully reduced the level of unpredictability of the quantity of injected fuel in subsequent injection events. A relationship between needle lift, injection pressure and the quantity of fuel injected was established. The effects of fuel injection parameters (main injection timing, split main separation and ratio) and engine operating parameters (boost pressure and EGR level) on emissions formations and fuel economy have been investigated at five operating points. Design of Experiments techniques were applied to investigate the effect of variables on pollutant emissions and fuel consumption. The sensitivity and linearity of responses to parameter changes have been analysed to assess the extent to which linear extrapolations will describe changes in smoke number (FSN) and oxides of nitrogen (NOx); and which parameters are the least constricting when it comes to adjustments of parameter settings on the FSN-NOx map. Comparing results for split main and single injection strategies at the five operating conditions shows that split main injection can be exploited to reduce NOx or FSN values at all conditions and both NOx and FSN simultaneously at high load conditions. The influence of changing engine speed and brake mean effective pressure (BMEP) on FSN and NOx emissions with given fixed values of parameter settings has been investigated. This established how much of the operating map could be covered by discrete calibration settings. Finally the variation in parameter settings required to maintain fixed FSN and NOx values across the operating map, near the optimum trade-off on the FSN-NOx map, was analysed. Combining the information gained from the individual investigations carried out highlighted some techniques that can be used to simplify the calibration task across the operating map, while also reducing the amount of experimental testing required.

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Animashaun, Lukman Aremu. "Tribochemistry of boron-containing lubricant additives on ferrous surfaces for improved internal combustion engine performance." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17660/.

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Global concerns for the environmental impact of pollutants from automotive sources require considerable reduction of phosphorus and sulphur-based antiwear additives in lubricating oils. One of such additives used as antiwear/extreme pressure (EP) additives in lubricating oils is Zinc Dialkyl DithioPhosphate (ZDDP). Potential replacements for ZDDP are antiwear/EP boron-based additives. In this study, a comprehensive evaluation of the tribological properties of model oils of different types of borate antiwear additives are considered for comparison to ZDDP on steel surfaces in tribo-contact. In this thesis, tribological experiments in pure sliding under boundary lubrication conditions were performed using pin-on-reciprocating plate test rig with variations of: additive concentrations in the oil, bulk-oil temperature, sliding process, dissolved, and free water contamination tests. The coefficient of friction response and antiwear performance of tribofilms were evaluated. Bulk oil analysis of the model oils were performed to evaluate their response to different thermal and oxidative conditions in comparison to ZDDP. In addition, chemical characterization of key crystalline boron compounds was done. The physical and chemical aspects of tribofilms generated during tribological tests were evaluated using surface analysis techniques such as: Optical white-light interferometry, Atomic Force Microscopy (AFM), Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM), Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Nanoindentation. One of the key findings of this study is that tribofilms from hydrolytically unstable borates additives gave poor antiwear performance compared to ZDDP and other synthetic borate additives with better resistance to hydrolysis. This study has revealed that boric acid is not directly responsible for the poor antiwear performance as previously understood. Tribochemistry results by this thesis has shown that high atomic concentration of boron and particles such as; boron nitride and carbides acts as third body abrasives, are responsible for the poor antiwear performance. The established antiwear mechanism of borate tribofilms relies on the digestion of abrasive iron oxides by trigonal structural groups in boron oxide. Results at different test conditions from this research have indicated that boric acid, iron oxyhydroxide, and tetragonal structural units in boron oxide plays a major role in this process. The established friction reducing mechanism of boron-containing tribofilms relies on the weak van der Waal’s of boric acid and passivation of its high energy edge-sites by moisture. Another major finding of this PhD thesis is that decomposition and volatility of boric acid at certain temperatures affects the easy shear of the lamellar. An important finding from this study indicated that the abnormal behaviour of boron oxide effect in borosilicate glass manufacture could also affect the antiwear performance and durability of tribofilms containing nanoparticle alkali borate ester. In addition, the hardness of built-up tribofilms from oils containing hydrated potassium borate was found to be comparable to ZDDP, unlike organic borates which gave significantly higher hardness. Another major finding of this research is that in moisture-rich atmosphere, borate tribofilms formed on ferrous surfaces was more wear-resistant than ZDDP due to their different tribochemistry.

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39

Ipakchi, Hassan. "Development and performance characteristics of a family of gas-fired pulsed combustors." Thesis, Middlesex University, 2000. http://eprints.mdx.ac.uk/13374/.

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Two nominally 15, and 30 kW Helmholtz-type pulsed combustors were designed and constructed. These were bench mounted with the heat exchangers (i.e. combustion chamber and tailpipe) immersed in the water bath. Their design was based upon the design of a nominally 7.5 kW pulsed unit previously developed at Middlesex University. The design enabled the lengths of the combustion chambers to be varied so that various combustion chamber volumes could be achieved. This provided a new dimension to the study of pulsed combustors which is lacking in many reported works. It was found that the required input rates could be achieved by scaling up or down each combustion chamber dimensions linearly by a factor of 1.5, while maintaining the geometry identical. Tests showed that the present design of pulsed combustors can operate successfully at various input rates of mains natural gas (93 % methane) with a maximum turn-down ratio of 1.8:1. Results indicated that the three developed combustors would generally operate in the fuel-lean condition. Interestingly, these tests revealed that the amount of excess air reduced as the combustion chamber volume (CCV) was increased. Systematic investigation on the three developed combustors showed that the temperature within the combustor was principally controlled by the air-to-fuel ratio (A/F). Analysis of the average measured NOx concentrations at various operating conditions indicated that NOx emission in this type of pulsed combustor is principally controlled by combustion temperature with no significant influence of combustion chamber volume, tailpipe length or scale of the combustors except in so far as these influenced the A/F and hence the temperature within the combustor. The dominant role of temperature on NOx production from these combustors become more evident when nitrogen or argon was injected into the system resulting in reduced NOx emissions at a given A/F. Systematic analysis of data indicated that as the amount of diluent increased, the temperature within the combustor decreased. Almost all the NOx values recorded were in the form of NO which is believed to be as a result of the high flame temperature (typically above 1850K). The minimum recorded NOx value was 5 ppm at the upper limiting value of excess air ratio, λ ; importantly it was round that at these high A/F values there was no significant reduction in overall efficiency of the pulsed units, showing calculated values above 90%. Analysis of data indicated that combustion temperature is also a primary factor controlling CO emissions from the present design of pulsed combustors. CO concentrations exhibited U-shaped characteristics when plotted vs λ, showing maximum values at the lowest and highest λ values. By changing water bath temperature (WBT) and hence modifying heat losses to the combustion chamber wall, it was shown that the quenching of the combustion reactions and incomplete mixing of air and gas prior to combustion are contributing factors to CO formation in this type of pulsed combustor. The developed pulsed combustors were operated successfully with standard test gases. The composition and flame stability of these test gases were similar to the standard test gases G21 (incomplete combustion gas), G222 (light back gas) and G23 (flame lift gas). Analysis of the exhaust gas composition showed similar trends to those obtained when burning mains natural gas; as the heat input was increased, O2 levels decreased while CO2 and NOx emission levels increased. Similarly, CO concentrations showed U-shaped characteristics when plotted against firing rate. Measurements of peak pulsing pressure and frequency were used as a guide to operation and stability performance of the pulsed units. It was found that the operating frequency was a function of configuration of the combustors and temperature of the internal gases. Frequency of operation showed a reciprocal correlation with volume of combustion chamber and tailpipe length and increased as the heat input was increased. Pulsing pressure amplitude also was influenced by change of configuration of the combustors, increasing as the CCV and tailpipe length were decreased. Analysis of experimental data obtained at fixed configuration of the combustors showed that the peak pulsing pressure was a strong function of the heat release per cycle in the present design of pulsed combustors. A major drawback of the use of pulsating combustors is the high noise level which is associated with their operation. It was found that it is possible to reduce overall noise levels of the pulsed burners to acceptable values by configuring the system appropriately. This included the use of expansion chambers at the inlet and the exhaust outlet which reduced the overall noise levels to a minimum value of 65 dBA.

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Ormond, Adam. "The influence of valve timing and other features on the combustion and emissions characteristics of a DISI engine." Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442289.

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Sappok, Alexander G. (Alexander Georg). "Emissions and in-cylinder combustion characteristics of Fischer-Tropsch and conventional diesel fuels in a modern CI engine." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35637.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. Includes bibliographical references (p. 137-140). Increasingly stringent emissions regulations, rising oil prices, and an increased focus on environmental awareness are driving the search for clean, alternative fuels. Derived from natural gas, coal, and even biomass Fischer-Tropsch (FT) fuels are one such alternative. The inherently clean nature of FT diesel coupled with the fact that FT diesel exhibits similar physical properties to those of conventional diesel make FT diesel an ideal candidate as both a blending agent with and eventual replacement for conventional petroleum-based diesel fuels. The potential for emissions reduction with FT diesel fuels in laboratory engine tests and on-road vehicle tests is well documented. While a number of chemical and physical characteristics of FT fuels have been attributed to the observed reduction in emissions, the actual effects of both the fuel properties and in-cylinder combustion characteristics in modern diesel engines are still not well understood. In this study a 2002, six-cylinder, 5.9 liter, Cummins ISB 300 diesel engine, outfitted with an in-cylinder pressure transducer, was subjected to a subset of the Euro III 13-mode test cycle under steady-state operating conditions. (cont.) Emissions and in-cylinder pressure measurements were conducted for neat FT diesel, low sulfur diesel (LSD), ultra-low sulfur diesel (ULSD), and a blend of FT/LSD. The experimental results show a significant reduction in regulated emissions with the neat FT fuel and a more than proportional reduction in particulate emissions for the blend. In order to provide further insight into the emissions behavior of the fuels, combustion characteristics were determined from a heat release analysis based on the in-cylinder pressure measurements. In addition, a detailed chemical analysis of the fuels and particulate emissions was carried out. The differences in the measured combustion characteristics and fuel properties were compared to the emissions variations between the fuels studied, and an explanation for the observed emissions behavior of the fuels was developed. by Alexander G. Sappok. S.M.

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Tippett, Esther Claire. "The effects of combustion chamber design on turbulence, cyclic variation and performance in an SI engine." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/28071.

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An experimental program of motored and fired tests has been undertaken on a single cylinder spark ignition engine to determine the influence of combustion chamber design on turbulence enhancement in the achievement of fast lean operation. Flow field measurements were taken using hot wire anemometry in the cylinder during motored operation. On line performance tests and in-cylinder pressure data were recorded for the operation of the engine by natural gas at lean and stoichiometric conditions over a range of speed and loads. Squish and squish jet action methods of turbulence enhancement were investigated for six configurations, using a standard bathtub cylinder head and new piston designs incorporating directed jets through a raised wall, a standard bowl-in-piston chamber and an original squish jet design piston. A non squish comparison was provided by a disc chamber. Peak Pressure and Indicated Mean Effective Pressure (IMEP), two parameters characterizing performance and cyclic variability, showed that enhanced turbulence by combustion chamber geometry is effective in improving performance at lean operation. The single jet action directed towards the spark was most effective in improving the efficiency at high speed and lean mixtures. The addition of jets to the single jet, or jet channels to the main squish action of the bowl- in-piston chamber, reduced performance and increased cyclic variability. Mass fraction burn analysis of the cylinder pressure data showed that squish action was most effective in the main burn period. Configurations with large squish area and centrally located spark produced the greatest reduction in both the initial and main burn periods. The potential for the squish jet action to improve engine drivability and increase the knock limit was exhibited in reduced coefficient of variance of IMEP and reduced ignition advance requirements. Directions for further research to exploit this potential for engines operated by alternative fuels are identified. Applied Science, Faculty of Mechanical Engineering, Department of Graduate

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Bale, Christopher J. C. "The application of advanced spark-ignition engine combustion systems for high-performance and a better environment." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/36018.

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This is a thesis that brings together work conducted over a thirty year period concerning the research, development and knowledge management of high perfonnance and low exhaust emission engines. The thesis includes nine published and refereed works that are discussed and appended. Internal combustion engines translate the chemical energy of a fuel into mechanical work by burning the fuel with air in a combustion chamber. It is demonstrated that this process can be improved beneficially with respect to power output, fuel economy and exhaust emissions, by efficient cylinder filling and the generation of enhanced charge motion characteristics at the point of ignition. The advantages of multivalve engines, particularly with 5-valves per cylinder, and the methods of producing and measunng good air flow and beneficial amounts of tumble or barrel swirl, are described. Two patents and three novel research techniques for air flow and air motion are presented and discussed. The combustion developments carried out by the author for competition and high-perfonnance road cars are presented as examples of the application of the theory and research.

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Baker, Christopher E. "The effect of transient dynamics of the internal combustion compression ring upon its tribological performance." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14068.

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The losses in an internal combustion engine are dominated by thermal and parasitic sources. The latter arises from mechanical inefficiencies inherent within the system, particularly friction in load bearing conjunctions such as the piston assembly. During idle and at low engine speeds, frictional losses are the major contributor to the overall engine losses as opposed to the dominant contribution of thermal losses under other driving conditions. Given the relatively small size and simple structure of the top compression ring, it has a disproportionate contribution to the total frictional losses. This suggests further analysis would be required to understand the underlying causes of compression ring behaviour throughout the engine cycle. The available literature on tribological analyses of compression rings does not account for the transient ring elastodynamics. They usually assume a rigid ring for film thickness and power loss predictions, which is not representative of the ring's dynamic response. A combined study of ring elastodynamic behaviour and its tribological conjunction is a comprehensive approach.

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Dombrovsky, Artem. "Synthesis of the 1D modelling of turbochargers and its effects on engine performance prediction." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/82307.

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Low fuel consumption is one of the main requirement for current internal combustion engines for passenger car applications. One of the most used strategies to achieve this goal is to use downsized engines (smaller engines while maintaining power) what implies the usage of turbochargers. The coupling between both machines (the turbocharger and the internal combustion engines) presents many difficulties due to the different nature between turbomachines and reciprocating machines. These difficulties make the optimal design of the turbocharged internal combustion engines a complicated issue. In these thesis a strong effort has been made to improve the global understanding of different physical phenomena occurring in turbochargers and in turbocharged engines. The work has been focused on the 1D modelling of the phenomena since 1D tools currently play a major role in the engine design process. Both experimental and modelling efforts have been made to understand the heat transfer and gas flow processes in turbochargers. Previously to the experimental analysis a literature review has been made in which the state of the art of heat transfer and gas flow modelling in turbochargers have been analysed. The experimental effort of the thesis has been focused on measuring different turbochargers in the gas stand and the engine test bench. In the first case, the gas stand, a more controlled environment, has been used to perform tests at different conditions. Hot tests with insulated and not insulated turbocharger have been made to characterise the external heat transfer. Moreover, adiabatic tests have been made to compare the effect of the heat transfer on different turbocharger variables and for the validation of the turbine gas flow models. In the engine test bench full and partial load tests have been made for model validation purposes. For the models development task, the work has been divided in heat flow models and gas flow models. In the first case, a general heat transfer model for turbochargers has been proposed based on the measured turbochargers and data available from previous works of the literature. This model includes a procedure of conductive conductances estimation, internal and external convection correlations and radiation estimation procedure. In the case of the gas flow modelling, an extended model for VGT performance maps extrapolation for both the efficiency and the mass flow has been developed as well as a model for discharge coefficient prediction in valves for two stage turbochargers. Finally, the models have been fully validated coupling them with a 1D modelling software simulating both the gas stand and the whole engine. On the one hand, the results of the validation show that compressor and turbine outlet temperature prediction is highly improved using the developed models. This results prove that the turbocharger heat transfer phenomena are important not only for partial load and transient simulation but also in full loads. On the other hand, the VGT extrapolation model accuracy is high even at off-design conditions. El bajo consumo de combustible es uno de los principales requerimientos de los motores de combustión interna actuales para aplicaciones de coches de pasajeros. Una de las estrategias más usadas para conseguir ese fin es el uso de motores "downsized" (motores más pequeños con la misma potencia) lo que implica el uso de turbocompresores. El acoplamiento entre ambas máquinas (el turbocompresor y el motor de combustión alternativo) presenta muchas dificultades debido a la diferente naturaleza entre las turbomáquinas y las máquinas alternativas. Estas dificultades convierten el diseño óptimo de los motores de combustión interna sobrealimentados en un asunto complicado. En esta tesis se ha realizado un importante esfuerzo para mejorar el entendimiento global de los diferentes fenómenos físicos que ocurren en los turbocompresores y en los motores sobrealimentados. El trabajo se ha centrado en el modelado 1D de los fenómenos puesto que las herramientas 1D juegan actualmente un papel principal en el proceso de diseño del motor. Se han realizado tanto esfuerzos experimentales como de modelado para el entendimiento de los procesos de transmisión de calor y de flujo de gases en turbocompresores. Previamente al análisis experimental se ha realizado una revisión de la literatura disponible en la que se ha analizado el estado del arte del modelado de transmisión de calor y flujo de gases en turbocompresores. El esfuerzo experimental de la tesis se ha centrado en la medida de diferentes turbocompresores en el banco de gas y en el banco motor. En el primer caso, se ha utilizado el banco de gas, un ambiente más controlado, para realizar ensayos en diferentes condiciones. Se han realizado ensayos calientes con y sin aislamiento del turbocompresor para caracterizar el flujo de calor externo. Además, se han realizado ensayos adiabáticos para comparar el efecto de la transmisión de calor sobre diferentes variables del turbocompresor y para la validación de los modelos de flujo de gases de la turbina. En el banco motor se han realizado ensayos a plena carga y a cargas parciales para usarlos en la validación. Para la tarea del desarrollo de los modelos, el trabajo se dividió en modelos de flujo de calor y modelos de flujo de gases. En el primer caso, se ha propuesto un modelo general de transmisión de calor para turbocompresores basado en los turbocompresores medidos y en datos disponibles de trabajos previos de la literatura. Este modelo incluye un procedimiento para la estimación de las conductancias conductivas, correlaciones de convección interna y externa y un procedimiento de estimación de la radiación. En el caso del modelado de flujo de gases, se ha desarrollado un modelo extendido para la extrapolación de mapas de funcionamiento de TGV tanto para el rendimiento como para el gasto másico además del modelo de predicción de coeficientes de descarga en válvulas de turbocompresores de doble etapa. Finalmente, los modelos han sido completamente validados con su acoplamiento a un software de modelado 1D simulando tanto el banco de turbos como el motor completo. Por un lado, los resultados de la validación señalan que la predicción de las temperaturas de salida de compresor y turbina mejora notablemente usando los modelos desarrollados. Este resultado demuestra que los fenómenos de transmisión de calor son importantes no sólo en simulaciones de cargas parciales y de transitorios sino también en plenas cargas. Por otro lado, la precisión del modelo de extrapolación de TGV es alta incluso en condiciones fuera de diseño. El baix consum de combustible és un dels principals requeriments dels motors de combustió interna actuals per a aplicacions de cotxes de passatgers. Una de les estratègies més usades per a aconseguir eixe fi és l'ús de motors "downsized" (motors més xicotets amb la mateixa potència) el que implica l'ús de turbocompressors. L'adaptament entre ambdues màquines (el turbocompressor i el motor de combustió alternatiu) presenta moltes dificultats degut a la diferent naturalesa entre les turbomàquines i les màquines alternatives. Estes dificultats convertixen el disseny òptim dels motors de combustió interna sobrealimentats en un assumpte complicat. En esta tesi s'ha realitzat un important esforç per a millorar l'enteniment global dels diferents fenòmens físics que ocorren en els turbocompressors i en els motors sobrealimentats. El treball s'ha centrat en el modelatge 1D dels fenòmens ja que les ferramentes 1D juguen actualment un paper principal en el procés de disseny del motor. S'han realitzat tant esforços experimentals com de modelatge per a l'enteniment dels processos de transmissió de calor i de flux de gasos en turbocompressors. Prèviament a l'anàlisi experimental s'ha realitzat una revisió de la literatura disponible en què s'ha analitzat l'estat de l'art del modelatge de transmissió de calor i flux de gasos en turbocompressors. L'esforç experimental de la tesi s'ha centrat en la mesura de diferents turbocompressors en el banc de gas i en el banc motor. En el primer cas, s'ha utilitzat el banc de gas, un ambient més controlat, per a realitzar assajos en diferents condicions. S'han realitzat assajos calents amb i sense aïllament del turbocompressor per a caracteritzar el flux de calor extern. A més, s'han realitzat assajos adiabàtics per a comparar l'efecte de la transmissió de calor sobre diferents variables del turbocompressor i per a la validació dels models de flux de gasos de la turbina. En el banc motor s'han realitzat assajos a plena càrrega i a càrregues parcials per a usar-los en la validació. Per a la tasca del desenvolupament dels models, el treball es va dividir en models de flux de calor i models de flux de gasos. En el primer cas, s'ha proposat un model general de transmissió de calor per a turbocompressors basat en els turbocompressors mesurats i en dades disponibles de treballs previs de la literatura. Este model inclou un procediment per a l'estimació de les conductàncies conductivas, correlacions de convecció interna i externa i un procediment d'estimació de la radiació. En el cas del modelatge de flux de gasos, s'ha desenvolupat un model estés per a l'extrapolació de mapes de funcionament de TGV tant per al rendiment com per al gasto màssic a més del model de predicció de coeficients de descàrrega en vàlvules de turbocompressors de doble etapa. Finalment, els models han sigut completament validats amb el seu adaptament a un software de modelatge 1D simulant tant el banc de turbos com el motor complet. D'una banda, els resultats de la validació assenyalen que la predicció de les temperatures d'eixida de compressor i turbina millora notablement usant els models desenrotllats. Este resultat demostra que els fenòmens de transmissió de calor són importants no sols en simulacions de càrregues parcials i de transitoris sinó també en plenes càrregues. D'altra banda, la precisió del model d'extrapolació de TGV és alta inclús en condicions fora de disseny. Dombrovsky, A. (2017). Synthesis of the 1D modelling of turbochargers and its effects on engine performance prediction [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/82307 TESIS

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Jalal, Aslan Sabahaldeen. "Design and performance investigation of flux-concentrated tubular linear generator for an external combustion free piston engine." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/4007.

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The increasing global desire for highly fuel efficient power systems and the need for environmentally friendly energy sources is driving much present research in electrical power. A linear power system, where a linear machine is driven directly by a free piston engine, offers scalability and a wide range applicability. Standalone power units, hybridised power systems and range extenders in electrified vehicles are all potential applications for this technology. This thesis explores the application of a Linear Joule Engine driving a Permanent Magnet Linear Machine for electrical power generation. Whereas most Joule cycle engines have a rotary compressor and expander, at smaller scale this configuration suffers from leakage around the blades. The linear engine uses a double acting free piston configuration running on the external combustion Joule-cycle, overcoming the low efficiency inherent in small scale gas turbines. The key element for electrical power generation, and the main focus of this thesis, is the development of a linear machine operating as a generator, the design of which is heavily constrained by the geometrical and the operational characteristics of the engine. Using specific constraints for an 5kW engine and by using two dimensional finite element analysis, a novel design methodology of tubular PM linear machine with modular armature winding and feasible arrangements of magnets on the translator member is outlined. The effect of core material, pole number and power conversion system on the machine design are investigated, highlighting the effect of the interconnected design variables on the resulting performance and material use, all satisfying design objectives. A Flux – Concentrated PM configuration is selected for further development. vi In order to accomplish an overall system performance investigation tool, at first the development of a general novel linear machine model is introduced and tested in a feedforward manner with accounts for all machine interacting electromagnetic forces. Then, a novel dynamic model incorporating both the linear machine model driven by the linear Joule engine model, coupled together in a closed loop form, is realized. The coupled model bridges mechanical and electrical parts of the engine-generator, and provides a solid dynamic performance prediction of the system focusing on identifying the effect of cogging force on system performance and the resultant electrical power loss and electrical efficiency. Compared with the reported cogging force reduction techniques, a novel structural technique and a selection criteria are presented with two dimensional axisymmetric finite element analysis verification showing the effectiveness of the proposed technique. Finally, a machine prototype of the selected design model is manufactured and tested on a bespoke test rig to validate the design model findings. Manufacturing recommendations and future achievable steps are reported for future development of the existing work.

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Magee, Samuel John. "Investigation of the performance and emissions characteristics of small capacity two-stroke cycle engines." Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388072.

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Hsieh, Wei-Dong, and 謝煒東. "Combustion Characteristics, Pollution Analysis and Engine Performance on Ethanol-Gasoline Fuels." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/88073157920205094496.

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碩士 國立成功大學 機械工程學系 88 This study is focused on the combustion characteristics, engine performance, and pollution analysis of different ratios of ethanol-gasoline blended fuels (E0,E5,E10,E20,E30). This study includes three parts, the experiments, the theory analysis of stagnation plane spray combustion, and the engine test. Throughout the experiment, we use stagnation plane spray burner to investigate the combustion characteristics of different ratios of ethanol-gasoline blended fuels. The results show that, with increasing ethanol content in the blend fuel, the equivalence ratio of the system when extinction gets higher. From the temperature analysis, we conclude that the flame speed of the blended fuel with less than 20% ethanol is mainly affected by the fuel-air equivalence ratio of the system. The characteristic of higher latent heat and lower heat of combustion of the ethanol will not show effects until the ration of ethanol in the blend fuels is over 30%. In theory analysis, we develop a model for the stagnation plane spray combustion to analyze the phenomena of fully pre-evaporized spray combustion and investigate factors that affect the combustion phenomena. These factors include concentration of gas fuel, flame stretch rate, Lewis number, the amount of liquid fuel and the ratio of ethanol in the blended fuels. The results of the theory analysis coincide with the results of experiments of stagnation plane spray combustion. During the engine test, we use different ratios of ethanol-gasoline blended fuels with different rpms and different throttle valves of engine as test conditions. The results show that using ethanol-gasoline blended fuels slightly increase the torque output and fuel consumption while the emissions of CO and HC decrease as a result of leaning effect due to addition of ethanol, the emission of CO2 increases as a result of better combustion situation. At last, emission of NOX depends on the operating condition of engine.

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Gunawan, Hardi. "Performance and combustion characteristics of a diesel-pilot gas injection engine." Thesis, 1992. http://hdl.handle.net/2429/2059.

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High pressure injection of natural gas with diesel liquid pilot fuel has been investigated in a single-cylinder two-stroke diesel engine of low compression ratio. The thermal efficiency and emissions of NOx, CO and HC were determined at 1200RPM as a function of load. Variations of the pilot-diesel energy to total heat energy ratio (in the range 15 -25%) strongly affected efficiency and emissions rate. Gas injection pressure was also shown to be an important variable. The thermal efficiency of the gas-diesel engine was shown to exceed that of the conventional diesel at full load, and is less at low load in the present configuration. The combustion rate analysis has been used to determine the pressure rise (ignition time) delay and combustion duration as well as the characteristic burning pattern. At low load late burning high cyclic variations, and incomplete combustion are associated with peak compression temperature lower than 900 K.

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Huang, Kuo-Cheng, and 黃國政. "Numerical Analysis of Ignition Characteristics and Combustion Performances in a Rotary Engine." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/36416393826224458602.

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碩士 逢甲大學 航太與系統工程所 97 This study used computational fluid dynamic (CFD) software, Fluent®, to simulate the combustion flows with methane as the fuel in the rotary engine by employing the technique of dynamic mesh, k-ε turbulence model, and finite-rate/eddy-dissipation combustion model provided by Fluent. Effects of different location and duration time of ignition on the engine performance were studied via flame propagation process, pressure and temperature changes in the combustion chamber, pressure-volume diagram, indicated horsepower and indicated mean effective pressure. Ignition location before top dead center displays better combustion performance indicated by horsepower and mean effective pressure. This is caused by the higher temperature and wider spread of flame to establish higher mean pressure and temperature in the combustion chamber to produce better combustion performances. In addition, the flame temperature and mean pressure are increased obviously when the duration of ignition is increased and therefore the mean effective pressure and indicated horsepower are performed.

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Dissertations / Theses on the topic 'Engine performance and combustion characteristics'

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