Dissertations / Theses: 'Turbocharged engines'

1

Hong, C. W. "Computer simulation of turbocharged spark ignition engines." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47281.

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2

Cieslar, Dariusz. "Control for transient response of turbocharged engines." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244951.

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The concepts of engine downsizing and down-speeding offer reductions in CO2 emissions from passenger cars. These reductions are achieved by reducing pumping and friction losses at part-load operation. Conventionally, rated torque and power for downsized units are recovered by means of turbocharging. The transient response of such engines is, however, affected by the static and dynamic characteristics of the turbo-machinery. Recent advances in engine simulation and control tools have been employed for the purpose of the research reported in this thesis to identify and verify possible air-path enhancements. A systematic method for evaluating various turbocharger assistance concepts is proposed and discussed in this thesis. To ensure a fair comparison of selected candidate systems, an easily reconfigurable controller providing a close-to-optimal operation, while satisfying physical limits, is formulated. This controller is based on the Model Predictive Control framework and uses a linearised mean value model to optimise the predicted behaviour of the engine. Initially, the controller was applied to a 1D simulation model of a conventional light-duty Diesel engine, for which the desired closed-loop features were verified. This procedure was subsequently applied to various air-path enhancement systems. In this thesis, a turbocharger electric assistance and various concepts based on compressed gas injection were considered. The capability of these systems to improve engine response during third gear tip-in manoeuvre was quantified. This investigation was also complemented with a parametric study of how effectively each of the considered methods used its available resources. As a result, injecting compressed gas into the exhaust manifold was identified as an effective method, which to date has attracted limited attention from engine research community. The effectiveness of the exhaust manifold assistance was experimentally verified on a light-duty Diesel engine. The sensitivity of the improvements to compressed gas supply parameters was also investigated. This led to the development of the BREES system: a low component count, compressed gas based system for reducing turbo-lag. It was shown that during braking manoeuvres a tank can be charged to the level sufficient for a subsequent boost assistance event. Such a functionality was implemented with a very limited set of additional components and only minor changes to the standard engine control.

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3

Chan, Siew Hwa. "Transient performance of turbocharged vehicle diesel engines." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46707.

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4

Andersson, Per. "Air charge estimation in turbocharged spark ignition engines /." Linköping : Dept. of Electrical Engineering, Linköping University, 2005. http://www.bibl.liu.se/liupubl/disp/disp2005/tek989s.pdf.

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5

Plianos, Alexandros. "Nonlinear modelling and control of turbocharged diesel engines." Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496800.

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The main focus of this thesis is the investigation of nonlinear control designs on the airpath of a diesel engine equipped with exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT). This problem presents strong couplings between controlled variables and actuators, since both EGR and VGT flows are driven by gases in the exhaust manifold. An additional coupling arises from the common shaft of the compressor and the turbine. The multivariable, highly nonlinear dynamics of the system gives motivation for model-based nonlinear control. Firstly, an eighth order mean-value model of the diesel engine is derived. This is consequently used to perform closed-loop simulations and to tune the controller gains offline. To reduce the complexity of the controllers, a third-order mean-value is used to design the nonlinear controllers.

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6

Craddock, J. P. "Investigations into the performance of highly turbocharged diesel engines." Thesis, University of Hertfordshire, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355851.

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7

Wiklund, Eric, and Claes Forssman. "Bypass Modeling and Surge Control for turbocharged SI engines." Thesis, Linköping University, Department of Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-3594.

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Since measurements in engine test cells are closely coupled with high costs it is of interest to use physically interpretable engine models instead of engine maps. Such engine models can also be used to do off-line tests of how new or altered components affects engine performance.

In the thesis an existing mean value engine model will be extended with a model of a compressor bypass valve. A controller for that valve will also be developed. The purpose with that controller is to save torque and boost pressure but at the same time avoid having the compressor entering surge during fast closing transients in the throttle position.

Both the extension and controller is successfully developed and implemented. The extension lowers the pressure after the compressor and increases the pressure before the compressor when the bypass valve is being opened and the controller shows better results in simulations than the controller used in the research lab. By using the proposed controller, as much as 5 percent higher torque can be achieved in simulations.

Finally there is a discussion on wastegate control alternatives and the use of TOMOC for optimization of wastegate control.

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8

Ren, Zizhong. "Theoretical and experimental study on sequentially turbocharged diesel engine performance." Thesis, Glasgow Caledonian University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388308.

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An investigation on the sequential turbocharging of a Kelvin TFSC6 6-cylinder 4- stroke marine diesel engine developing 320 kW at 1200 r/min is reported in this thesis. The sequential turbocharging (ST) system, utilising turbochargers of unequal size, resulted in significant improvement when compared with previously designed systems. The engine test results show that the new sequential turbocharging system improves the engine performance at both high speeds and low speeds except at or near to the 'transfer' speed. The engine low speed performance is obviously improved with the fuel saving of up to 7 g/kwh for the 1st sequence. The engine high speed performance is also improved for the 2nd sequence where both turbochargers are in operation. There is some boost air leakage from the delivery pipe which is used for connecting the peak unit to the intercooler inlet. This restricts the 2nd sequence gains. An optimised sequence transfer control mode is also proposed in this research and validated by both test and simulation results. Two control valves, one at the peak unit turbine inlet and the other at the compressor outlet, are specifically designed for the ST system and both of them worked very well during the engine test programme. Both simulation models - "Filling& Emptying" and "Method of Characteristic" were modified and used for the sequential turbocharging simulation. The modified program of the "Filling& Emptying" model can be used to analyse and compare the effects of different exhaust systems. It can also be applied to simulate and design a pulse converter system for a sequential turbocharged diesel engine. The modification on the "MOC" program makes it possible to simulate the exhaust pressure wave for the ST system with different turbocharger arrangements (concentrated or separated). The consideration of pressure losses in the 'three branch junction' boundary improves the simulation accuracy. In addition, a comprehensive engine test data acquisition and control system has been developed in this study. The advanced system with many new features can be used for engine condition monitoring. diagnosis and other similar applications for engine development and test. The efficiency and reliability of the system have been corroborated by the engine test process. The real time data process, analysis and display in various forms are available using the developed program with 'LabVIEW'. The proposed self-adaptive auto-load setting with optimised parameters is validated as an economic solution for engine load control with an early type of hydraulic dynamometer.

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9

Smith, Leslie Arthur. "Prediction of air mass flowrate in turbocharged four-stroke diesel engines." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46557.

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10

Rämmal, Hans. "Studies of flow duct acoustics with applications to turbocharged engines." Doctoral thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10590.

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A number of experimental and theoretical studies, performed in the field of technical flow duct acoustics are presented in this thesis. The acoustical methods treated are implemented on turbocharged IC-engines and engine gas exchange system components. A new method based on the well-known two-load technique has been developed. The method was applied to characterise the source data of various piston-engines with non-linear behaviour including a 6 cylinder turbo-charged truck diesel engine. The source characterisation results were compared to the results obtained using the linear two-load technique. It was demonstrated that the new non-linear multi-load technique gives improved results when the source is slightly non-linear. The use of active one-port models has been tested to characterize an air terminal device (ATD) as a source of flow generated noise. In order to predict the noise generation at different operating points of the device a scaling law was derived and verified. In the experimentally derived scaling law a flow speed dependence of 3 was found for the narrow band spectra, corresponding to a dipole-like behavior of the source in the plane wave range. The proposed technique was validated successfully and the results indicated a good prediction of in-duct sound generation by the air terminal device. Sound reflection from hot flow duct openings has been investigated experimentally. The reflection coefficient was measured for flow temperatures up to 500 ºC and jet velocities up to 108m/s. The results have been compared with famous Munt’s theory. It was concluded that at low Mach number and Helmholz number cases the results agree well with the Munt’s model. This was the first experimental validation of the theory for hot flow conditions. Experimental procedures to determine the sound transmission through automotive turbo-charger compressors were developed and described in detail. An overview of a unique turbocharger testing facility established at KTH CICERO in Stockholm is given. The facility can be used to measure acoustic two-port data for turbo-compressors. Results from measurements on a passenger car turbo-compressor are presented and the influence of operating conditions on the sound transmission is discussed. Current wave action models developed in CMT for computation of the gas exchange processes in I.C. engines have been implemented to determine the acoustic wave transmission through the turbo- compressor. The models are validated with the experimental data and the results are presented for different operating conditions of a Volvo passenger car turbo-compressor.
QC 20100809

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11

Westin, Fredrik. "Simulation of turbocharged SI-engines - with focus on the turbine." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-216.

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12

Rämmal, Hans. "Studies of flow duct acoustics with applications to turbocharged engines /." Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10590.

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13

Degong, Dang. "Theoretical and experimental diesel engine system studies, with special reference to temperature and altitude derating." Thesis, University of Bath, 1989. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234139.

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14

Fatohi, Wathik Noel. "Some aspects of high pressure charging of automotive diesel engines." Thesis, University of Hertfordshire, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315669.

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15

Ismail, Muhammad Izzal. "One-dimensional modelling of pulse separation strategy, waste-gated turbines and electric turbocharger systems for downsized turbocharged gasoline engines." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/58097.

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The demand for CO2 emission reduction for modern road vehicles has seen engine downsizing become a key trend in internal combustion engine design: a smaller engine has reduced pumping, frictional and heat losses, and therefore better fuel economy. Turbocharger technology is one of the enabling technologies, offering lower specific fuel consumption and producing more power for a given engine capacity. The turbocharger matching process, which specifies an appropriate turbocharger design for a particular engine, is crucial in obtaining optimum engine performance. In order to achieve a high level of accuracy in the system-level prediction, high fidelity turbocharger models are required; but such models have not yet reached fruition. The present study has assessed the effect of preserving the exhaust pulse energy from an engine right through to the turbine on the steady and transient engine performance. A combination of appropriate turbine sizing and pulse-divided exhaust manifold was applied, and as a consequence, lower back pressure and improved engine scavenging reduced residual content by 28%, while the brake specific fuel consumption (BSFC) improves by approx. 1.2% on average over speed range. Furthermore, the implementation of electric turbo assist (ETA) system on the engine results in better fuel economy by 2.4%. The present work has also assessed the overall engine performance using a commercial 1-D gas dynamics simulation tool by modelling the waste-gated turbines in a novel manner. This approach has been validated experimentally. The study also examined the benefits of electric turbocharger systems for a highly-downsized engine, a modified version of the baseline engine. Some potential multi-boosting systems were applied, and the overall benefits in terms of engine performance were assessed. An integration of an electric turbocharger and a low-pressure turbine with electric turbo compounding gives the best advantages particularly in pumping loss, residual and transient performance while improving fuel economy in comparison with other systems.

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16

Thomasson, Andreas. "Modeling and control of actuators and co-surge in turbocharged engines." Doctoral thesis, Linköpings universitet, Fordonssystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-105687.

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The torque response of the engine is important for the driving experience of a vehicle. In spark ignited engines, torque is proportional to the air flow into the cylinders. Controlling torque therefore implies controlling air flow. In modern turbocharged engines, the driver commands are interpreted by an electronic control unit that controls the engine through electromechanical and pneumatic actuators. Air flow to the intake manifold is controlled by an electronic throttle, and a wastegate controls the energy to the turbine, affecting boost pressure and air flow. These actuators and their dynamics affect the torque response and a lot of time is put into calibration of controllers for these actuators. By modeling and understanding the actuator behavior this dynamics can be compensated for, leaving a reduced control problem, which can shorten the calibration time. Electronic throttle servo control is the first problem studied. By constructing a control oriented model for the throttle servo and inverting that model, the resulting controller becomes two static compensators for friction and limp-home nonlinearities, together with a PD-controller. A gain-scheduled I-part is added for robustness to handle model errors. The sensitivity to model errors is studied and a method for tuning the controller is presented. The performance has been evaluated in simulation, in test vehicle, and in a throttle control benchmark. A model for a pneumatic wastegate actuator and solenoid control valve, used for boost pressure control, is presented. The actuator dynamics is shown to be important for the transient boost pressure response. The model is incorporated in a mean value engine model and shown to give accurate description of the transient response. A tuning method for the feedback (PID) part of a boost controller is proposed, based on step responses in wastegate control signal. Together with static feedforward the controller is shown to achieve the desired boost pressure response. Submodels for an advanced boost control system consisting of several vacuum actuators, solenoid valves, a vacuum tank and a vacuum pump are developed. The submodels and integrated system are evaluated on a two stage series sequential turbo system, and control with system voltage disturbance rejection is demonstrated on an engine in a test cell. Turbocharged V-type engines often have two parallel turbochargers, each powered by one bank of cylinders. When the two air paths are connected before the throttle an unwanted oscillation can occur. When the compressors operate close to the surge line and a disturbance alters the mass flow balance, the compressors can begin to alternately go into surge, this is called co-surge. Measurements on co-surge in parallel turbocharged engines are presented and analyzed. A mean value engine model, augmented with a Moore-Greitzer compressor model to handle surge, is shown to capture the cosurge behavior. A sensitivity analysis shows which model parameters have the largest influence of the phenomena. The compressor operation in the map during co-surge is studied, and the alternating compressor speeds are shown to have a major impact on the continuing oscillation. Based on the analysis, detection methods and a controller are proposed, these detect co-surge and control the turbo speeds to match during co-surge. The controller is evaluated both in simulation and on a test vehicle in a vehicle dynamometer, showing that co-surge can be detected and the oscillations quelled.

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17

Carden, Clare Margaret. "Gas dynamics in exhaust systems of turbocharged medium-speed diesel engines." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47375.

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18

Gurney, D. C. "The application of 1D simulation to model turbocharged and supercharged spark ignition engines." Thesis, University of Warwick, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271942.

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19

Wang, Zheng. "DEVELOPMENT OF ACOUSTIC MODELS FOR HIGH FREQUENCY RESONATORS FOR TURBOCHARGED IC-ENGINES." Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91335.

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Automotive turbo compressors generate high frequency noise in the air intake system. This sound generation is of importance for the perceived sound quality of luxury cars and may need to be controlled by the use of silencers. The silencers usually contain resonators with slits, perforates and cavities. The purpose of the work reported is to develop acoustic models for these resonators where relevant effects such as the effect of realistic mean flow on losses and possibly 3D effects are considered. An experimental campaign has been undertaken where the two-port matrices and transmission loss of four sample resonators has been measured without flow and for two different mean flow speeds (M=0.05 & M=0.1) using two source location technique. Models for the four resonators have been developed using a 1D linear acoustic code (SIDLAB) and a FEM code (COMSOL Multi-physics). Different models, from the literature, for including the effect of mean flow on the acoustic losses at slits and perforates have been discussed. Correct modeling of acoustic losses for resonators with complicated geometry is important for the simulation and development of new and improved silencers, and the present work contributes to this understanding. The measured acoustic properties compared well with the simulated model for almost all the cases.

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20

McKenzie, Jacob Elijah. "The autoignition characteristics of turbocharged spark ignition engines with exhaust gas recirculation." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100139.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis. Page 145 blank.
Includes bibliographical references (pages 131-134).
The societal demand for vehicles with high efficiency and low emissions has spurred considerable changes to the automotive internal combustion engine within the past decade. Reductions in the displacement volume and increases in maximum output per unit of displacement are among the characteristics adopted to meet the fuel economy targets of world governments. However, the extent to which these changes in engine configuration may be pursued in search of efficiency is limited by several fundamental phenomena. The intent of this research project is to investigate the modeling of one of these phenomena - the autoignition of an unburned portion of the air-fuel mixture - and a potential strategy intended to delay the occurrence of this frequently damaging type of combustion reaction. The autoignition abatement approach studied entails the recirculation of burned exhaust gasses which serve to dilute the air-fuel mixture and reduce maximum unburned gas temperatures Experimental testing was performed on two different types of exhaust gas recirculation (EGR) system - one which extracts exhaust gases from upstream of the catalytic converter and another which extracts gases from downstream - in order to determine if the changes in composition that occur across the catalyst affect the autoignition abatement characteristics of the recirculated exhaust. This testing indicated that differences between the alternative installations are dominated by changes in the flow dynamics of the exhaust system, with no definite changes attributable to compositional differences. An empirical method of predicting the occurrence of autoignition using experimental data was then developed based on an approach originally proposed by Livengood and Wu. Ignition delay correlations were developed that provide accurate autoignition prediction over a range of speeds, loads, air-fuel equivalence ratios and dilution rates. Additionally, a new statistical model for autoignition is proposed that captures the cycle-to-cycle variation in autoignition intensity and relates these variations to the thermodynamic state of the charge.
by Jacob Elijah McKenzie.
Ph. D.

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21

Zhou, Junqiang. "CONTROL OF OVER-ACTUATED SYSTEMS WITH APPLICATION TO ADVANCED TURBOCHARGED DIESEL ENGINES." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420810533.

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22

Backhouse, R. J. "The dynamic behaviour and feedback control of a turbocharged automotive diesel engine with variable geometry turbine." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375340.

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23

Lindén, Erik, and David Elofsson. "Model-based turbocharger control : A common approach for SI and CI engines." Thesis, Linköpings universitet, Institutionen för systemteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-70288.

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In this master’s thesis, a turbine model and a common control structure for theturbocharger for SI and CI-engines is developed. To design the control structure,simulations are done on an existing diesel engine model with VGT. In order tobe able to make simulations for engines with a wastegated turbine, the model isextended to include mass flow and turbine efficiency for that configuration. Thedeveloped model has a mean absolute relative error of 3.6 % for the turbine massflow and 7.4 % for the turbine efficiency. The aim was to control the intake manifoldpressure with good transients and to use the same control structure for VGTand wastegate. By using a common structure, development and calibration timecan be reduced. The non-linearities have been reduced by using an inverted turbinemodel in the control structure, which consists of a PI-controller with feedforward.The controller can be tuned to give a fast response for CI engines and a slowerresponse but with less overshoot for SI engines, which is preferable.

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24

Meindl, Emmeram [Verfasser]. "Numerical and Experimental Investigation of Knock in Turbocharged Direct Injection Spark Ignition Engines / Emmeram Meindl." München : Verlag Dr. Hut, 2017. http://d-nb.info/1149580119/34.

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25

Schäfer, Lukas [Verfasser]. "Modeling and Simulation of Spark Ignition in Turbocharged Direct Injection Spark Ignition Engines / Lukas Schäfer." München : Verlag Dr. Hut, 2016. http://d-nb.info/1106593502/34.

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26

Cedrone, Kevin David. "Control strategy for hydrocarbon emissions in turbocharged direct injection spark ignition engines during cold-start." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81693.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 185-191).
Gasoline consumption and pollutant emissions from transportation are costly and have serious, demonstrated environmental and health impacts. Downsized, turbocharged direct-injection spark ignition (DISI) gasoline engines consume less fuel and achieve superior performance compared with conventional port fuel injected spark ignition (PFI-SI) engines. Although more efficient, turbocharged DISI engines have new emissions challenges during cold start. DISI fuel injection delivers more liquid fuel into the combustion chamber, increasing the emissions of unburned hydrocarbons. The turbocharger slows down activation (warm-up) of the catalytic exhaust after-treatment system. The objective of this research is to find a control strategy that: 1. Accelerates warm-up of the catalyst, and 2. Maintains low emissions of unburned hydrocarbons (UBHCs) during the catalyst warm-up process. This research includes a broad experimental survey of engine behaviour and emission response for a modern turbocharged DISI engine. The study focuses on the idle period during cold-start for which DISI engine emissions are worst. Engine experiments and simulations show that late and slow combustion lead to high exhaust gas temperatures and mass flow rate for fast warm-up. However, late and slow combustion increase the risk of partial-burn misfire. At the misfire limit for each parameter, the following conclusions are drawn: 1. Late ignition timing is the most effective way to increase exhaust enthalpy flow rate for fast catalyst warm-up. 2. By creating a favourable spatial fuel-air mixture stratification, split fuel injection can simultaneously retard and stabilize combustion to improve emissions and prevent partial-burn misfire. 3. Excessive trapped residuals from long valve overlap limit the potential for valve timing to reduce cold-start emissions. 4. Despite their more challenging evaporation characteristics, fuel blends with high ethanol content showed reasonable emissions behaviour and greater tolerance to late combustion than neat gasoline. 5. Higher exhaust back-pressure leads to high exhaust temperature during the exhaust stroke, leading to significantly more post-flame oxidation. 6. Post-flame oxidation in the combustion chamber and exhaust system play a critical role in decreasing the quantity of catalyst-in emissions due to hydrocarbons that escape primary (flame) combustion. A cold start strategy combining late ignition, 15% excess air, and high exhaust backpressure yielded the lowest cumulative hydrocarbon emissions during cold start.
by Kevin David Cedrone.
Ph.D.

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27

Elmqvist-Möller, Christel. "1-D simulation of turbocharged SI engines : focusing on a new gas exchange system and knock prediction." Licentiate thesis, KTH, Machine Design (Div.), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4218.

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This licentiate thesis concerns one dimensional flow simulation of turbocharged spark ignited engines. The objective has been to contribute to the improvement of turbocharged SI engines’ performance as well as 1 D simulation capabilities.

Turbocharged engines suffer from poor gas exchange due to the high exhaust pressure created by the turbine. This results in power loss as well as high levels of residual gas, which makes the engine more prone to knock.

This thesis presents an alternative gas exchange concept, with the aim of removing the high exhaust pressure during the critical periods. This is done by splitting the two exhaust ports into two separate exhaust manifolds.

The alternative gas exchange study was performed by measurements as well as 1-D simulations. The link between measurements and simulations is very strong, and will be discussed in this thesis.

As mentioned, turbocharged engines are prone to knock. Hence, finding a method to model knock in 1-D engine simulations would improve the simulation capabilities. In this thesis a 0-D knock model, coupled to the 1-D engine model, is presented

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Elmqvist-Möller, Christel. "1-D simulation of turbocharged SI engines : focusing on a new gas exchange system and knock prediction /." Stockholm : KTH, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4218.

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29

Klasén, Erik. "Modeling and Estimation of Long Route EGR Mass Flow in a Turbocharged Gasoline Engine." Thesis, Linköpings universitet, Fordonssystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131102.

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Due to the continuous work in the automobile industry to reduce the environmental impact, reduce fuel consumption and increase efficiency, new technologies need to be developed and implemented in vehicles. For spark ignited engines, one technology that has received more attention in recent years is long route Exhaust Gas Recirculation (EGR), which means that exhaust gases after the turbine are transported back to the volume before the compressor in the air intake system of the engine. In this work, the components of the long route EGR system is modeled with mean value engine models in Simulink, and implemented in a existing Simulink engine model. Then different methods for estimating the mass flow over the long route EGR system are compared, and the transport delays for the recirculated exhaust gases in the engines air intake system are modeled. This work is based on measurements done on an engine rig, on which a long route EGR system was installed. Finally, some ideas on how a long route EGR system on a gasoline engine can be controlled are presented based on the results in this thesis work.

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30

Gómez, Gil Javier. "Development of an altitude simulator and analysis of the performance and emissions of turbocharged Diesel engines at different altitudes." Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/101284.

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En el pasado, la investigación de los motores de combustión interna se ha centrado en la reducción del combustible y las emisiones, manteniendo constante el rendimiento. Además, en los últimos años la presión está aumentando aún más para los fabricantes de motores. La nueva homologación es un gran desafío, principalmente debido a la introducción de los ciclos de emisiones de conducción reales (RDE), lo que obligará a homologar los coches en condiciones reales de conducción, más dinámicas y con un amplio rango de condiciones ambientales, donde la altitud ambiente puede llevar a los 1300 metros sobre el nivel del mar. Hoy en día, los fabricantes tienen diferentes formas de ensayar los motores y los automóviles en condiciones de altitud. Pruebas en altitud real, donde el automóvil, los ingenieros y los sistemas de medida y ensayo deben desplazarse a un lugar en altitud durante largos períodos de tiempo. La otra solución es ensayar el automóvil en una cámara hipobárica, donde se puede controlar la presión. Sin embargo, estas cámaras son costosas, difíciles de operar e intensivas en espacio y recursos. En la presente tesis, se desarrolla un simulador de altitud, que presentará otra alternativa para el ensayo de motores en altitud. En este simulador de altitud, el motor está a presión ambiente y solo sus conductos de admisión y escape están a la altitud del ensayo. En la tesis, se describe el principio de operación del simulador de altitud, sus diferentes elementos y su efecto sobre el rendimiento del simulador de altitud, así como las estrategias de control aplicadas para controlar las diferentes variables y elementos. Para estudiar el potencial del simulador de altitud, un motor diésel turboalimentado se ha ensayado a diferentes altitudes y su rendimiento y emisiones se han comparado con los obtenidos en una cámara hipobárica. Además, el motor se ha ensayado a diferentes altitudes en ciclos dinámicos y se ha analizado su rendimiento y emisiones, cuyos resultados muestran que la estrategia de control del motor cuando está operando en altitud se centra en la protección de los diferentes elementos sin tener en cuenta las emisiones. Por estas razones, es importante estudiar diferentes estrategias para reducir las emisiones de los motores en altitud. Finalmente, se han realizado diferentes estudios paramétricos cambiando la geometría de las válvulas del motor y colector de escape para analizar su efecto sobre la temperatura de entrada de los sistemas de postratamiendo y el consumo especifico de combustible, como una forma de reducir el tiempo que tardan dichos sistemas en alcanzar la temperatura objetivo con mayor eficiencia de trabajo.
In the last decades, the internal combustion engines research has been focused in the reduction of the fuel consumption and emissions while keeping constant the performance. Besides, in the last years the pressure is increasing even more to the engine manufacturers. The new homologation is a big challenge, mainly because of the introduction of the real driving emissions cycles, which will force to homologate the cars under real driving conditions, more dynamic and with an extended range of ambient conditions. The ambient altitude can reach up to 1300 meters above sea level. Nowadays, the manufacturers have different ways to test the engines and cars in altitude conditions. Real altitude tests, where the car, engineers and testing systems have to be displaced to an altitude place during long periods of time. The other solution is to test the car in a hypobaric chamber, where the pressure can be controlled. However, these chambers are expensive, difficult to operate and intensive in space and resources. In the present thesis, an altitude simulator is developed, which will introduce another alternative to test engines in altitude. In this altitude simulator, the engine or car is at room pressure and only its intake and exhaust pipes are at the tested altitude. In the thesis, it is described the altitude simulator operation principle, its different elements and their effect on the altitude simulator performance, as well as the control strategies applied to control the different variables and elements. In order to proof the potential of the altitude simulator, a turbocharged diesel engine is tested at different altitudes and its performance and emissions results are compared with those obtained in a hypobaric chamber. Also the engine is tested at the different altitudes in dynamic cycles and its performance and emissions are analyzed, showing that the engine control strategy when it is operating in altitude is focused in the protection of the different elements without taking into account the emissions. For these reason, it is important to study different strategies to reduce engine emissions in altitude. Finally, different parametric studies changing different geometries of the engine valves and exhaust manifold in order to analyze its effect on the aftertreatment inlet temperature and the specific fuel consumption, as a way to reduce the time that it takes to the aftertreatment to reach the target conversion efficiency temperature.
En el passat, la investigació dels motors de combustió interna s'ha centrat en la reducció del combustible i les emissions, mantenint constant el rendiment. A més, en els últims anys la pressió està augmentant encara més per als fabricants de motors. La nova homologació és un gran desafiament, principalment a causa de la introducció dels cicles d'emissions de conducció reals (RDE), el que obligarà a homologar els cotxes en condicions reals de conducció, més dinàmiques i amb un ampli rang de condicions ambientals, on l'altitud ambient pot portar els 1300 metres sobre el nivell del mar. Avui dia, els fabricants tenen diferents formes d'assajar els motors i els automòbils en condicions d'altitud. Proves en altitud real, on l'automòbil, els enginyers i els sistemes de mesura i assaig han de desplaçar-se a un lloc en altitud durant llargs períodes de temps. L'altra solució és assajar l'automòbil en una cambra hipobàrica, on es pot controlar la pressió. No obstant això, aquestes càmeres són costoses, difícils d'operar i intensives en espai i recursos. En la present tesi, es desenvolupa un simulador d'altitud, que presentarà una altra alternativa per a l'assaig de motors en altitud. En aquest simulador d'altitud, el motor està a pressió ambient i només els seus conductes d'admissió i escapament estan a l'altitud de l'assaig. A la tesi, es descriu el principi d'operació del simulador d'altitud, els seus diferents elements i el seu efecte sobre el rendiment del simulador d'altitud, així com les estratègies de control aplicades per controlar les diferents variables i elements. Per estudiar el potencial del simulador d'altitud, un motor dièsel turboalimentat s'ha assajat a diferents altituds i el seu rendiment i emissions s'han comparat amb els obtinguts en una cambra hipobàrica. A més, el motor s'ha assajat a diferents altituds en cicles dinàmics i s'ha analitzat el seu rendiment i emissions, els resultats mostren que l'estratègia de control del motor quan està operant en altitud se centra en la protecció dels diferents elements sense tenir en compte les emissions. Per aquestes raons, és important estudiar diferents estratègies per reduir les emissions dels motors en altitud. Finalment, s'han realitzat diferents estudis paramètrics canviant la geometria de les vàlvules del motor i col·lector d'escapament per analitzar el seu efecte sobre la temperatura d'entrada dels sistemes de postratamiendo i el consum especäifico de combustible, com una forma de reduir el temps que triguen aquests sistemes en arribar a la temperatura objectiu amb major eficiència de treball.
Gómez Gil, J. (2018). Development of an altitude simulator and analysis of the performance and emissions of turbocharged Diesel engines at different altitudes [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/101284
TESIS

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Greplová, Kristýna. "Design For Six Sigma." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230032.

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The aim of the master’s thesis is analysis of practical application limits of waste-gate TwinScroll turbocharger located in BMW X6 M vehicle by using DFSS (Design For Six Sigma) tools. The goal is to create a special measurement device for a measurement of waste gate leakage with chance of testing all sorts of characteristics having impact on key parameters of turbocharger.

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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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33

Westin, Fredrik. "Accuracy of turbocharged SI-engine simulations." Licentiate thesis, KTH, Machine Design, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1491.

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This licentiate thesis deals mainly with modelling ofturbocharged SIengines. A model of a 4-cylinder engine was runin both steady state and transient conditions and the resultswere compared to measured data. Large differences betweenmeasurements and simulations were detected and the reasons forthis discrepancy were investigated. The investigation showedthat it was the turbocharger turbine model that performed in anon-optimal way. To cope with this, the turbine model containedparameters, which could be adjusted so that the model resultsmatched measured data. However, it was absolutely necessary tohave measured data to match against. It was thus concluded thatthe predictivity of the software tool was too poor to try topredict the performance of various boosting systems. Thereforemeans of improving the modelling procedure were investigated.To enable such an investigation a technique was developed tomeasure the instantaneous power output from, and efficiency of,the turbine when the turbocharger was used on the engine.

The projects initial aim was to predict, throughsimulations, the best way to boost a downsized SI-engine with avery high boost-pressure demand. The first simulation run on astandard turbocharged engine showed that this could not be donewith any high accuracy. However, a literature study was madethat presents various different boosting techniques that canproduce higher boost pressure in a larger flow-range than asingle turbocharger, and in addition, with smallerboost-pressure lag.

Key words:boosting, turbocharging, supercharging,modelling, simulation, turbine, pulsating flow, unsteadyperformance, SI-engine, measurement accuracy

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Kristoffersson, Ida. "Model Predictive Control of a Turbocharged Engine." Thesis, KTH, Reglerteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107508.

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Engine control becomes increasingly important in newer cars. It is therefore interesting to investigate if a relatively new control method as Model Predictive Control (MPC) can be useful in engine control in the future. One of the advantages of MPC is that it can handle contraints explicitly. In this thesis basics on turbocharged engines and the underlying theory of MPC is presented. Based on a nonlinear mean value engine model, linearized at multiple operating points, we then implement both a linear and a nonlinearMPC strategy and highlight implementation issues. The implemented MPC controllers calculate optimal wastegate position in order to track a requested torque curve and still make sure that the constraints on turbocharger speed and minimum and maximum opening of the wastegate are fulfilled.

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Dale, Adrian Peter. "Radial, vaneless, turbocharger turbine performance." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/11363.

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Wang, Xu. "A study into vibrations of turbocharger blading with a lacing wire." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/10754.

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The vibration of a turbocharger blade and dynamic characteristics of bladed packets connected by a lacing wire have been studied. The study was carried out using three analytical and experimental methods. They are: Modal Testing, Electronic Speckle Pattern Interferometry (ESPD and Finite Element Analysis (FEA)). Vibration modes of a turbocharger blade with aerodynamic profile, with and without a lacing wire, were identified using model blades with simplified geometry. The separation of coupled modes was achieved using ESPI tests. The modes of vibrations of bladed packets were identified. The effect of inter-blade coupling through a lacing wire is that a cluster of sub-modes are generated in bladed packets corresponding to each fundamental mode of the freestanding blade, the number of the sub-modes being equal to the number of blades in the packet. Apart from the fundamental sub-mode, the vibration of all other submodes are out of phase with different phase relations. The stiffness of the lacing wire and its location with respect to the blade make great contributions towards certain mode clusters in terms of mode shapes and natural frequencies. The nonlinearity of the stiffness of the deformed lacing wire caused by centrifugal force was established. The coupling of this non linearity with different vibration amplitudes, due to different phase relation, results in the dynamic mistuning in lacing wire stiffness. This mistuning is considered to be a major attribute in reducing the responses at resonance.

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Sutton, Anthony James. "Experimental evaluation of compressor variable geometry in a turbocharger compressor." Thesis, University of Bath, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289813.

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Jo, Young Suk. "Turbocharged engine operations using knock resistant fuel blends for engine efficiency improvements." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81606.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 61).
Engine downsizing with a turbocharger has become popular these days in automotive industries. Downsizing the engine lets the engine operate in a more efficient region, and the engine boosting compensates for the power loss accompanied by downsizing. However, the use of high boost in a downsized engine is limited by knock. Changing operating parameters such as spark timing has shown to be effective in avoiding knock. However, those strategies usually deteriorate efficiency of the engine. Another method to suppress knock without lowering efficiency is to use knock resistant fuels. Among them ethanol has gotten a large attention due to its renewable characteristics. About 13.3 billion gallons of ethanol were produced in 2012, and about 99 % of them are used as fuel added to gasoline. However, the optimal use of ethanol in a spark ignited engine as a knock suppressing additive is not well quantified. Also, operation limitations of a knock free engine are not well known. The objective of this project was to determine the knock onset engine operating conditions and to explore the potential of a direct injection of ethanol enhanced fuels. An engine with a turbocharger was used to measure efficiencies of the engine over the wide range of operating points. Speed range was chosen from 1500 rpm to 3000 rpm in which vehicle is usually driven in the driving cycle. Then, knock onset of different ethanol-gasoline blends, from 0 % ethanol to 85 % ethanol contents with 91 RON gasoline, were determined. Generated engine fuel consumption maps with knock onset limits were utilized in a vehicle driving simulation tool. In a simulation, the consumption of gasoline and knock suppressing fuels was determined in different driving cycles. Finally, effects of downsizig and spark retard on ethanol fraction in the fuel were determined.
by Young Suk Jo.
S.M.

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39

Abdullah, Abu Hasan. "The application of high inlet swirl angles for broad operating range turbocharger compressor." Thesis, University of Bath, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320555.

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40

Renberg, Ulrica. "1D engine simulation of a turbocharged SI engine with CFD computation on components." Licentiate thesis, KTH, Machine Design (Div.), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9162.

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1D engine simulations of turbocharged engines are difficult to

Techniques that can increase the SI- engine efficiency while keeping the emissions very low is to reduce the engine displacement volume combined with a charging system. Advanced systems are needed for an effective boosting of the engine and today 1D engine simulation tools are often used for their optimization.

This thesis concerns 1D engine simulation of a turbocharged SI engine and the introduction of CFD computations on components as a way to assess inaccuracies in the 1D model.

1D engine simulations have been performed on a turbocharged SI engine and the results have been validated by on-engine measurements in test cell. The operating points considered have been in the engine’s low speed and load region, with the turbocharger’s waste-gate closed.

The instantaneous on-engine turbine efficiency was calculated for two different turbochargers based on high frequency measurements in test cell. Unfortunately the instantaneous mass flow rates and temperatures directly upstream and downstream of the turbine could not be measured and simulated values from the calibrated engine model were used. The on-engine turbine efficiency was compared with the efficiency computed by the 1D code using steady flow data to describe the turbine performance.

The results show that the on-engine turbine efficiency shows a hysteretic effect over the exhaust pulse so that the discrepancy between measured and quasi-steady values increases for decreasing mass flow rate after a pulse peak.

Flow modeling in pipe geometries that can be representative to those of an exhaust manifold, single bent pipes and double bent pipes and also the outer runners of an exhaust manifold, have been computed in both 1D and 3D under steady and pulsating flow conditions. The results have been compared in terms of pressure losses.

The results show that calculated pressure gradient for a straight pipe under steady flow is similar using either 1D or 3D computations. The calculated pressure drop over a bend is clearly higher1D engine simulations of turbocharged engines are difficult to using 1D computations compared to 3D computations, both for steady and pulsating flow. Also, the slow decay of the secondary flow structure that develops over a bend, gives a higher pressure gradient in the 3D calculations compared to the 1D calculation in the straight pipe parts downstream of a bend.

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Baranski, Jacob A. "Experimental Investigation of Octane Requirement Relaxation in a Turbocharged Spark-Ignition Engine." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1375262182.

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42

Nishimoto, Keane T. (Keane Takeshi) 1981. "Design of an automobile turbocharger gas turbine engine." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/41810.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
Includes bibliographical references (leaf 24).
The turbocharger gas turbine engine was designed with the intent of being built as a demonstration for the Massachusetts Institute of Technology Department of Mechanical Engineering courses 2.005 and 2.006 to supplement material covered. A gas turbine operates on an open version of the Brayton cycle and consists of a compressor, a combustion chamber and a turbine. An automobile turbocharger was chosen because it contains a compressor and turbine on a common shaft. Designs for the combustion chamber, oil system, fuel system, and ignition system were created based on research of similar projects. Many of the necessary parts were also specified.
by Keane T. Nishimoto.
S.B.

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43

Rezaeian, M. "Modelling of engine transmission systems for heavy vehicles : the differential compound engine versus the turbocharged engine." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484306.

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44

Roberts, Stefan Ross. "Non-intrusive knock detection in a turbocharged, dual fuel engine." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq22664.pdf.

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45

McCoy, Colleen (Colleen M. ). "Fuel economy of a turbocharged, single-cylinder, four-stroke engine." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112556.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 56-57).
Agriculture is the main source of livelihood for a majority of India's population. However, despite the number of workers, the yield and the yield of principal crops in India is much lower than that in developed nations. One of the reasons for this is the lack of farming mechanization in India. One of the common ways to run farming equipment is by using a single-cylinder, four-stroke diesel engine. Diesel engines can be turbocharged in order to make them more efficient for less cost. A method has been found to turbocharge a single-cylinder diesel engine by adding an air capacitor to form a buffer between the intake and exhaust strokes. This thesis analyzes how the size and heat transfer of the air capacitor for this turbocharged diesel engine are correlated to engine performance and fuel economy. According to the modeled engine, a 3.0 liter capacitor had better peak power and fuel economy at high loads and speeds than a 2.4 or 1.25 liter capacitor. Additionally, forced convection cooling on the capacitor using a fan allowed the intake air density to increase, and the engine to have better fuel economy than the . However the peak power and fuel economy of the modeled naturally aspirated engine was better than the turbocharged engine for speeds below 2500 rpm. The general trends from the model were reflected in the experimental data. The forced convection increased cooling, and improved the intake air density. However, it was difficult to make any confident recommendations about the fuel economy based on the experimental data.
by Colleen McCoy.
S.B.

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46

Ghazy, Mohamed Riad Aly. "Exciting forces and their relationship to turbocharged diesel engine vibration." Thesis, University of Southampton, 1986. https://eprints.soton.ac.uk/52293/.

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The work presented here quantifies the forces applied to the main bearings of three six-cylinder turbocharged diesel engines and reviews their exciting properties in both time and frequency domains. The engine structure response at the bearing supports and the outer surfaces are correlated. Vibration acceleration was measured, in the three different directions, at the engine main bearings and the outer surface. The liner vibrations were also measured. A theoretical model for calculating the bearing forces and estimating the bearing moment characteristics is proposed. The calculated bearing forces are investigated in both time and frequency domains. The characteristics of the forces driving the piston across the cylinder clearance are calculated. The characteristics of the forces acting on the liner by the piston are also calculated. Combining the results of the measurements with the theoretical model for force calculation, a technique for estimating the actual running clearance of the piston is presented. A technique for deriving the displacement from the measured acceleration is developed. By representing the engine response in terms of displacement it is possible to recognise the applied force time history and thus the identification of the specific parts of the engine structure primarily excited by moments and by direct force. It is shown that the engine structure response is a transient phenomenon and is maximum in the vicinity of the applied force. The displacement technique for quantifying engine response provides detailed information of the distortion of the running engine enabling the prediction of mechanical inputs which control the turbocharged engine noise.

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47

Raimbault, Vincent. "Benefit of air intake optimization for new turbocharged gasoline engine." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0024.

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Ces dernières années les ventes de moteurs à allumage commandé sont croissantes. Pourtant les exigences en termes d’émissions de CO2 et d’émissions polluantes sont devenues plus contraignantes, taxant lourdement les dépassements. De plus le cycle d’homologation a évolué vers un élargissement de la fenêtre d’utilisation du moteur ou les émissions sont réglementées. La réduction de cylindrée « downsizing » opérée ces dernières années a permis de réduire les consommations notamment grâce à la réduction des pertes par pompage. Les performances ont pu être maintenues par l’adoption de système de suralimentation et notamment du turbocompresseur. Celui-ci présente toutefois une lacune à bas régime où il ne peut fournir une réponse instantanée et où la pression desuralimentation est limitée. De même à plus haut régime le fort taux de compression utilisé pour augmenter le rendement du moteur rend difficile le contrôle du cliquetis. Cette thèse s’est focalisée sur l’utilisation des ondes de pression pour améliorer la réponse du moteur à bas régime. Tout d’abord avec des outils de simulation puis en validation sur banc moteur. Une seconde partie a permis de développer une architecture de ligne d’admission d’air permettant de réduire la température d’admission afin d’augmenter la résistance au cliquetis et d’augmenter l’avance à l’allumage. La température d’échappement est ainsi réduite. Celle-ci est un élément dimensionnant de la stratégie moteur qui a maintenu, dans ces travaux, un mélange stoechiométrique afin de limiter les émissions polluantes
The last years have witnessed a strong increase of the sold spark ignition engines. Furthermore the new regulations are formally constraining pollutant emissions and CO2 with high fines. In the same time the new homologation driving cycle extends the engine operating conditions where the emissions need to be controlled. The downsizing has been a strong lever over the last years to improve the fuel consumption with reduction of the throttling and thus the pumping losses. With the downsizing, the turbocharger has been widely adopted to maintain the output performance. The implementation of turbocharger challenges the time to torque and the low end torque at low engine speed. In the same time the increase of boost pressure associated to high compression ratio confront the knock controls at maximum power operating conditions. This thesis focuses on acoustic boosting with volumetric efficiency enhancement to improve the low end torque and the time to torque. Firstly a simulation model allows taking into account the combustion behavior as well as the turbocharger characteristics. The intake geometry has been optimized to enhance the engine response time and low end torque. The second part deals with the pressure wave action used to reduce the intake temperature and thus improve the knock resistance being beneficial for exhaust gas temperature reduction. The interaction between the waves created the different cylinder is demonstrated. The test has confirmed the power increase while maintaining lambda 1 and thus keeping the three way catalyst efficient

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Rivera, Gilbert D. "Turbochargers to small turbojet engines for uninhabited aerial vehicles." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA346353.

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Thesis (Degree of Aeronautical and Astronautical Engineer) Naval Postgraduate School, June 1998.
Thesis advisor(s): Garth V. Hobson, David W. Netzer. "June 1998." Includes bibliographical references (p. 73). Also available online.

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Hakeem, Imtiaz. "Steady and unsteady performance of mixed-flow turbines for automotive turbochargers." Thesis, Imperial College London, 1995. http://hdl.handle.net/10044/1/7402.

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Pai, Ajith V. "Air induction noise investigation during turbocharger surge events in petrol engines." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19449.

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Abstract:

Turbocharging is used as a means to downsize petrol engines, thereby, producing more power for a lower engine size, when compared with a naturally aspirated engine. Due to the presence of a throttle valve in the intake system in petrol engines, flow is restricted at the outlet pipe of the compressor during low load engine operation. For example, during transient tip out tip in maneuvers. Hence, there is a chance of the turbocharger operating in near surge or surge conditions and, thus, generating surge noise. This Thesis describes an experimental and simulation method to predict and measure the turbocharger surge noise. Initially, experimental transient tip-in and tip-out maneuver was performed on a non turbocharged car with a petrol engine. The measured noise level in the intake manifold, at a low frequency of up to 1200 Hz, was analysed and was shown not to represent surge noise. Next, a one dimensional simulation method was applied to simulate the noise of the engine and this demonstrated an increase in the acoustic pressure level in the intake manifold during the tip in and tip out maneuver. However, a surge noise pattern was not observed in the analysis of acoustic pressure signals in the intake system using Short Time Fourier Transform (STFT). The simulation procedure was also used to inform the design of an experimental rig to recreate the surge noise under laboratory conditions. An experimental turbocharger noise rig, designed and built for this purpose, is explained in the Thesis. Important component parts likely to be involved in the surge noise generation such as the intake system, compressor, throttle body, compressor recirculation valve and measurement and control systems were integrated into the test rig. Background noise contributions from the electric motor, AC mains, supercharger pulley, throttle body, inverter fan, throttle body gearing and structural vibration of the supporting structure were identified from the analysed frequency components of the signals from surface microphone measurements taken at the intake system. This helped to clearly identify the surge noise frequency components (3250 Hz) in the STFT analysis. The fundamental mechanism of noise generation was identified using an analysis of the experimental results and a frequency calculation for vortex shedding and the radial acoustic resonances. One of the main conclusions of the Thesis is that the compressor recirculation valve (CRV) open or close position, the CRV delay time and the throttle position are major contributing factors to the cause of the surge noise. Another major conclusion is that the radial acoustic resonance may be a mechanism of surge noise generation. Finally, a passive solution to reduce the surge noise is proposed. A pipe with cross ribs is designed as a passive solution using the radial acoustic resonance calculation and the corresponding nodal patterns. This solution demonstrated a measured intake system noise reduction of up to 10dB under compressor surge conditions.

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Dissertations / Theses on the topic 'Turbocharged engines'

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