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Viewing 1 to 30 of 167
2012-09-10
Technical Paper
2012-01-1735
Alexander Darlington, Dariusz Cieslar, Nick Collings, Keith Glover
Delivering acceptable low end torque and good transient response is a significant challenge for all turbocharged engines. As downsized gasoline engines and Diesel engines make up a larger and larger proportion of the light-duty engines entering the market, the issue takes on greater significance. Several schemes have been proposed to improve torque response in highly boosted engines, including the use of electrical assist turbochargers and compressed air assist. In this paper we examine these methods with respect to their effectiveness in improving transient response and their relative performance along with some of the practical considerations for real world application. Results shown in this paper are from 1-D simulations using the Ricardo WAVE software package.
2012-09-10
Technical Paper
2012-01-1734
Mitsunori Ishii
The design parameters of a turbo-compound engine system affecting the thermal efficiency and engine output have been analyzed, considering the allowable limit of the maximum cylinder pressure, exhaust temperature and other factors. By adjusting the values of the engine compression ratio to 20, the cross sectional area ratio of the turbine inlet to 0.4, and the compressor pressure ratio to 2.2 at full load and to 1.7 at part load, the thermal efficiencies of approximately 40% at full load and 25% at part load have been obtained in turbo-compound engine. Furthermore, the changes the optimum values are comparatively small, even if the engine compression ratio is greatly changed from 22 to 14.
2012-09-10
Technical Paper
2012-01-1733
Peter Kattwinkel, Christoph Reith, Martin Petersson
The use of fatty acid methyl esters (FAME), often referred to as biodiesel, instead of fossil diesel fuel is under consideration in order to increase the share of fuels from renewable sources and to reduce greenhouse gas emissions. In Europe, commercial diesel fuels already contain up to 7% biodiesel. Higher biodiesel blends or the use of pure biodiesel are probable measures to further increase the share of fuels from renewable sources. Due to its different feedstock and refining process, the specification of biodiesel reveals some important distinctions in comparison with standard diesel fuel. The current work aims to discuss the possible implications of biodiesel utilization on the aftertreatment systems of recent heavy-duty diesel (HDD) vehicles compliant with EURO VI legislation. In particular, the effect of biodiesel on heat-up operation, i.e., the increase of the exhaust gas temperature by catalytic combustion of fuel within a diesel oxidation catalyst (DOC), is investigated.
2012-09-10
Technical Paper
2012-01-1740
G Pitcher, J W G Turner, R J Pearson
Five different fuels, including gasoline, commercial E85, pure methanol and two mixtures of gasoline, ethanol and methanol, (GEM), configured to a target stoichiometric air fuel ratio have been investigated in a fully-optically-accessed engine. The work investigated effects of injection duration, and performed spray imaging, thermodynamic analysis of the combustion and OH imaging, for two fixed engine conditions of 2.7 and 3.7 bar NMEP at 2000 rpm. The engine was operated with constant ignition timing for all fuels and both loads. One of the most important results from this study was the suitability of a single type of injector to handle all the fuels tested. There were differences observed in the spray morphology between the fuels, due to the different physical properties of the fuels. The energy utilisation measured in this study showed differences of up to 14% for the different GEM fuels whereas an earlier in-vehicle study had showed only 2 to 3%.
2012-09-10
Journal Article
2012-01-1741
James Baustian, Leslie Wolf
Findings from an intermediate ambient temperature vehicle driveability study for isobutanol gasoline blends are reported. The pattern for the study was Coordinating Research Council Project CM-138-02, which investigated the effects of ethanol on cold-start/warm-up performance and Driveability Index. Objectives of the present study were: (a) to evaluate the efficacy of the current ASTM Driveability Index (DI) in predicting cold-start and warm-up driveability performance for isobutanol gasolines and (b) if required, identify modifications to the DI definition and specification limits for isobutanol blends. The test fuel matrix included fifteen fuels with nominal vapor pressures of 55 kPa (8 psi) at DI levels of 1150, 1200, 1250, and 1300 and isobutanol concentrations of 0, 16, and 24 volume percent. Twelve port- and direct-fuel-injected vehicles, which included US Tier 2 passenger cars and light-duty trucks from model years 2005 through 2008, were used to evaluate the test fuels.
2012-09-10
Journal Article
2012-01-1737
Scott McBroom, Robert A. Smithson, Roberto Urista, Christopher Chadwell
This paper describes advances in variable speed supercharging, including benefits for both fuel economy and low speed torque improvement. This work is an extension of the work described in SAE Paper 2012-01-0704 [8]. Using test stand data and state-of-the-art vehicle simulation software, a NuVinci continuously variable planetary (CVP) transmission driving an Eaton R410 supercharger on a 2.2 liter diesel was compared to the same base engine/vehicle with a turbocharger to calculate vehicle fuel economy. The diesel engine was tuned for Tier 2 Bin 5 emissions. Results are presented using several standard drive cycles. A Ford Mustang equipped with a 4.6 liter SI engine and prototype variable speed supercharger has also been constructed and tested, showing low speed torque increases of up to 30%. Dynamometer test results from this effort are presented. The combined results illustrate the promise of variable speed supercharging as a viable option for the next generation of engines.
2012-09-10
Technical Paper
2012-01-1738
Stephen R. Nattrass, Wayne R. Jones
The demonstration benefit from fuel-borne fuel-economy additives to a precision of 1%, or better, traditionally requires very careful experimental design and considerable resource intensity. In practice, the process usually requires the use of well-defined drive cycles (e.g. emission certification cycles HFET, NEDC) in conjunction with environmentally-controlled chassis dynamometer facilities. Against this background, a method has been developed to achieve high-precision fuel economy comparison of gasoline fuels with reduced resource intensity and under arbitrary real-world driving conditions. The method relies upon the inference of instantaneous fuel consumption via the collection of OBD data and the simultaneous estimation of instantaneous engine output from vehicle dynamical behaviour.
2012-09-10
Technical Paper
2012-01-1730
Jean P. Roy, Robert Panora, Joseph Gehret, Ranson Roser, Bruce Falls, Richard Geiss
Controlling exhaust gas temperature in a dual-stage catalyst system improves by a factor of three (or more) its capability to tolerate air-fuel ratio (AFR) variability and maintain compliance with stationary engine emission standards enforced in CA. This system is ideally suited for combined heat and power (CHP) generating units, in which heat is intentionally extracted from the engine exhaust gases to improve overall system thermal efficiency. Engines fueled with low-pressure natural gas typically employ fumigation fuel delivery systems. When operated at stoichiometric AFR using typical feedback fuel metering strategies and a three-way catalyst (TWC), these systems cannot reliably achieve the fuel control precision required to satisfy stringent emission requirements. Small rich or lean deviations in AFR result in large increases in tailpipe CO (rich) or NOx (lean). In the 1980's, automobile OEMs employed dual-stage catalyst systems to address a similar issue.
2012-09-10
Journal Article
2012-01-1731
Klaus Schrewe, Simon Steigert, Peter Neumann
Full flow particulate filters are a state of the art solution for many serial production diesel engine applications. They are very effective for removing ≻ 90% of particulate mass and ≻ 99% of the particulate number from the exhaust gas of diesel engines. Many diesel engines have to work at load profiles which necessitate active regeneration procedures to ensure continued engine operation and the reliability of the full flow particulate filter. Passive regeneration via NO₂, as a cost-effective solution, cannot be used as the sole method for all applications, due to restrictions such as, insufficient engine-out NOX/PM ratio, low exhaust gas temperature level or occasionally poor fuel quality. To meet the Tier 4 emission legislation casually partial flow particulate filters enable sufficient particulate reduction at boundary conditions where full flow DPF is not applicable.
2012-09-10
Technical Paper
2012-01-1728
Iason Dimou, Alexander Sappok, Victor Wong, Shuji Fujii, Hirofumi Sakamoto, Kazuya Yuuki, Claus Dieter Vogt
Diesel particulate filters (DPF) are a common component in emission-control systems of modern clean diesel vehicles. Several DPF materials have been used in various applications. Silicone Carbide (SiC) is common for passenger vehicles because of its thermal robustness derived from its high specific gravity and heat conductivity. However, a segmented structure is required to relieve thermal stress due to SiC's higher coefficient of thermal expansion (CTE). Cordierite (Cd) is a popular material for heavy-duty vehicles. Cordierite which has less mass per given volume, exhibits superior light-off performance, and is also adequate for use in larger monolith structures, due to its lower CTE. SiC and cordierite are recognized as the most prevalent DPF materials since the 2000's. The DPF traps not only combustible particles (soot) but also incombustible ash. Ash accumulates in the DPF and remains in the filter until being physically removed.
2012-09-10
Journal Article
2012-01-1760
Juan Du
This paper presents a method of calculating temperature field of the piston by using a wavelet neural network (WNN) to identify the unknown boundary conditions. Because of the complexity of the heat transfer and limitations of experimental conditions of heat transfer analysis of the piston in a diesel engine, boundary conditions of the piston temperature field were usually obtained empirically, and thus the result itself was uncertain. By employing the capability of resolution analysis from a wavelet neural network, the method obtains improved boundary heat transfer coefficients with a limited number of measured temperatures. Using FEA software iteratively, results show the proposed wavelet neural network analysis method improves the prediction of unknown boundary conditions and temperature distribution consistent with the experimental data with an acceptable error.
2012-09-10
Technical Paper
2012-01-1758
Mustapha Mahdaoui, Abdelouahad Ait Msaad, Mhamed Mouqallid, Elhoussin Affad
The overall goal of all engine researchers is to enhance fuel economy and reduce emissions. To achieve this objective, one should reduce the cycle-to-cycle variations in the combustion process. It is well known that cycle to cycle variations in combustion significantly influence the performance of spark engines. Traditionally, it has been explained as being the result of random fluctuations in equivalence ratio and fluid flow conditions due to the unsteady nature of turbulent flow in the engine. This paper presents a numerical study of the effect of the random inflow conditions and initial conditions to cycle-to-cycle variations in-cylinder flow. This study has been performed with the commercial CFD (computational fluid dynamic) code (FLUENT) coupled with our own development based on UDF facilities given by FLUENT.
2012-09-10
Technical Paper
2012-01-1759
Zhelin Dong, Guohua Chen, Yankun Jiang, Chunfa Wang
A transient gas-solid heat transfer model for the 3-D (three-dimensional) coupling components in internal combustion chamber was built. In order to implement this model, a transient heat transfer program based on FEM (finite-element method) was developed, the KIVA3V code was improved, and a KIVA-FEM interface program was developed. A special treatment for the grid generation were designed and utilized. The 3-D transient non-uniform gas temperature field and convective heat transfer coefficient distribution near the combustion chamber wall can be obtained using this heat transfer model. In addition, both steady and transient temperature fields of the 3-D coupling component system of a gasoline engine were calculated and analyzed. The results show that the temporal and spatial non-uniformity of thermal boundary conditions has an important influence on the steady temperature field, transient temperature field and heat flux of the combustion chamber wall.
2012-09-10
Technical Paper
2012-01-1745
Wataru Matsui, Tetsu Suzuki, Yasuo Ohta, Soichiro Ito, Yo Tanaka, Yutaka Kikuchi, Yasuhiro Daisho, Hisakazu Suzuki, Hajime Ishii
N₂O is known to have a significantly high global warming potential. We measured N₂O emissions in engine-bench tests by changing the NO/NH₃ ratio and exhaust gas temperature at the oxidation catalyst inlet in a heavy-duty diesel engine equipped with a urea SCR (selective catalytic reduction) system. The results showed that the peak N₂O production ratio occurred at an exhaust gas temperature of around 200°C and the maximum value was 84%. Moreover, the N₂O production ratio increased with increasing NO/NH₃. Thus, we concluded that N₂O is produced via the NO branching reaction. Based on our results, two methods were proposed to decrease N₂O formation. At low temperatures ~200°C, NO should be reduced by controlling diesel combustion to lower the contribution of NO to N₂O production. This is essential because the SCR system cannot reduce NOx at low temperatures.
2012-09-10
Technical Paper
2012-01-1743
S. F. Benjamin, M. Gall, C. A. Roberts
Use of selective catalytic reduction technology is the most popular strategy for removing NOx from lean diesel exhaust. The reductant is essentially ammonia and this has been supplied as a spray of urea droplets, but more recently alternative technology where ammonia gas is released from a storage medium has become a viable alternative. Experiments have been carried out on an engine test rig run to steady state conditions using NOx composed of either 25% or 50% of NO₂, with ammonia gas as the reductant. This was a 1D study where a long 10 degree diffuser provided uniform temperature and velocity profiles to the SCR catalyst brick. Under the transient conditions that occur during drive cycles, the dosing of the ammonia can deviate from the optimum. In this study, the dosage rate of ammonia was held at a fixed value, while the engine load was varied.
2012-09-10
Journal Article
2012-01-1744
Yuki Bisaiji, Kohei Yoshida, Mikio Inoue, Nobuyuki Takagi, Takao Fukuma
The details of Di-Air, a new NOx reduction system using continuous short pulse injections of hydrocarbons (HC) in front of a NOx storage and reduction (NSR) catalyst, have already been reported. This paper describes further studies into the deNOx mechanism, mainly from the standpoint of the contribution of HC and intermediates. In the process of a preliminary survey regarding HC oxidation behavior at the moment of injection, it was found that HC have unique advantages as a reductant. The addition of HC lead to the reduction or metallization of platinum group metals (PGM) while keeping the overall gas atmosphere in a lean state due to adsorbed HC. This causes local O₂ inhibition and generates reductive intermediate species such as R-NCO. Therefore, the specific benefits of HC were analyzed from the viewpoints of 1) the impact on the PGM state, 2) the characterization of intermediate species, and 3) Di-Air performance compared to other reductants.
2012-09-10
Technical Paper
2012-01-1742
Roger Cracknell, Arjun Prakash, Robert Head
Laminar burning velocity is a fundamental combustion property of any fuel/air mixture. Formulating gasoline fuel blends having faster burning velocities can be an effective strategy for enhancing engine and vehicle performance. Formulation of faster burning fuels by changing the fuel composition has been explored in this work leading to a clear correlation between engine performance and fuel burning velocity. In principle a gasoline vehicle should be calibrated to give optimal ignition timing (also known as MBT - minimum spark advance for best torque) while at the same time avoiding any possible engine knock. However, modern downsized/boosted engines frequently tend to be limited by knock and the spark timing is retarded in respect of the optimum. In such scenarios, faster burning fuels can lead to a more optimum combustion phasing resulting in a more efficient energy transfer and hence a faster acceleration and better performance.
2012-09-10
Technical Paper
2012-01-1747
Nic van Vuuren, Hamid Sayar
The recent implementation of new rounds of stringent nitrogen oxides (NOx) emissions reduction legislation in Europe and North America is driving the introduction of new automotive exhaust aftertreatment systems. One of these technologies comprises a catalyst that facilitates the reactions of ammonia (NH₃) with the exhaust nitrogen oxides (NOx) to produce nitrogen (N₂) and water (H₂O). This technology is referred to as Selective Catalytic Reduction (SCR). The ammonia is delivered by a separate fluid supply and injection system to the exhaust in the form of AUS-32 (Aqueous Urea Solution), and is also known under its commercial name of AdBlue® in Europe, and DEF - Diesel Exhaust Fluid - in the USA. The development and application of current production AUS-32 injection systems typically rely on spray diagnostics techniques that were implemented for the gasoline port injector. These data are often obtained under standard room temperature conditions.
2012-09-10
Technical Paper
2012-01-1746
Dihya Adouane, Hugo Dutilleul, Philippe Guibert, Mario Teixeira, Patrick Da Costa
Comparative study of impact of thermal aging on both surface morphology and catalyst performances was performed over fully formulated commercial lean NOx Trap using hydrothermal (oven) and engine aging for 5 hours at 750°C and 5 hr at 800°C. Investigations show that engine aging lead to more important degradation than hydrothermal aging because of the greater structural degradations that happened after engine aging: sintering of Pt particles, reaction of support (γAl₂O₃) with the storage material and a higher drop of surface area. It follows a decrease of oxidation and storage efficiency particularly after engine aging. During lean rich cycle environment, the rich step was not efficient to remove all the stored NOx due to storage on Ba-Bulk sites leading to accumulation of NOx after each cycle. The observed trend after engine aging was attributed to the presence of sulfur and mainly to soot as engine aging was performed with low concentration of sulfur in fuel.
2012-09-10
Journal Article
2012-01-1650
Sebastian Stenger, Steffi Köhler, Anna-Theresia Nasch, Reinhard Leithner, Stephan Scholl, Ulrike Krewer, Peter Eilts
This study investigates the technical feasibility of onboard carbon capture in vehicles. In fact there are two different main concepts of hybrid electric vehicles with batteries and range extenders proposed. The first concept uses an Internal Combustion Engine as range extender. Carbon dioxide is separated from the flue gas of this Internal Combustion Engine by chemical or physical absorption. In the second concept a solid oxide fuel cell (SOFC) is used as a range extender. The CO remaining in the anode exhaust gas is not combusted as usual by mixing anode and cathode exhaust gases but shifted with water vapor, sufficient available in the anode exhaust gas flow, to H₂ and CO₂. The H₂ is separated by a membrane permeable only for H₂ and recycled by the methane flow to the SOFC stack. Carbon dioxide can then be separated by simply condensing the water vapor of the anode exhaust gas of the SOFC.
2012-09-10
Technical Paper
2012-01-1651
Akira Kikusato, Hiroyuki Fukasawa, Kazutoshi Nomura, Jin Kusaka, Yasuhiro Daisho
Natural gas is an attractive alternative fuel for internal combustion engines. Homogeneous charge compression ignition (HCCI) combustion is considered to be one of the most promising measures for increasing thermal efficiency and reducing emissions, but it is difficult to control and stabilize its ignition and combustion processes. This paper describes an experimental study of natural gas combustion utilizing two types of ignition assistance. Spark assistance, which is used for conventional spark ignition (SI) engines, and pilot diesel injection, hereinafter called diesel pilot, which generates multiple ignition points by using a small injection of diesel that accounts for 2% of the total heat release for the cycle. The performance of these two approaches was compared with respect to various combustion characteristics when burning homogeneous natural gas mixtures at a high compression ratio.
2012-09-10
Technical Paper
2012-01-1647
Jiri Vavra, Michal Takats, Vojtech Klir, Marcel Skarohlid
In certain applications, the use of natural gas can be beneficial when compared to conventional road transportation fuels. Benefits include fuel diversification and CO₂ reduction, allowing future emissions regulations to be met. The use of natural gas in vehicles will also help to prepare the fuel and service infrastructure for future transition to gaseous renewable fuels. The composition of natural gas varies depending on its source, and engine manufacturers must be able to account for these differences. In order to achieve highly fuel flexible engines, the influence of fuel composition on engine properties must first be assessed. This demand is especially important for engines with high power densities. This paper summarizes knowledge acquired from engine dynamometer tests for different compositions of natural gas. Various levels of hydrocarbons and hydrogen in a mixture with methane have been tested at full load and various engine speeds.
2012-09-10
Technical Paper
2012-01-1649
Satoshi Taniguchi, Masahiko Masubuchi, Koji Kitano, Kazuhisa Mogi
The Diesel Dual Fuel (DDF) vehicle is one of the technologies to convert diesel vehicles for natural gas usage. The purpose of this research was to study the possibility of a DDF vehicle to meet emission standards for diesel vehicles. This research was done for small passenger vehicles and commercial vehicles. The exhaust emissions compliance of such vehicles in a New European Driving Cycle (NEDC) mode which was composed of Urban Driving Cycles (UDC) and an Extra Urban Driving Cycle (EUDC) was evaluated. (see APPENDIXFigure A1) In this study, the passenger vehicle engine, compliant with the EURO4 standard, was converted to a DDF engine. Engine bench tests under steady state conditions showed similar result to previous papers. Total hydrocarbon (HC) emission was extremely high, compared to diesel engine. The NEDC mode emissions of the DDF vehicle were estimated based on these engine bench test results.
2012-09-10
Technical Paper
2012-01-1644
Mayank Mittal, Harold Schock, Guoming Zhu
A direct-injection and spark-ignition single-cylinder engine with optical access to the cylinder was used for the combustion visualization study. Gasoline and ethanol-gasoline blended fuels were used in this investigation. Experiments were conducted to investigate the effects of fuel injection pressure, injection timing and the number of injections on the in-cylinder combustion process. Two types of direct fuel injectors were used; (i) high-pressure production injector with fuel pressures of 5 and 10 MPa, and (ii) low-pressure production-intent injector with fuel pressure of 3 MPa. Experiments were performed at 1500 rpm engine speed with partial load. In-cylinder pressure signals were recorded for the combustion analyses and synchronized with the high-speed combustion imaging recording. Visualization results show that the flame growth is faster with the increment of fuel injection pressure.
2012-09-10
Technical Paper
2012-01-1646
Adrian Irimescu
Several studies have been performed to investigate the effects of using hydrogen in spark ignition (SI) engines. One general conclusion that emerged was that stoichiometric operation of premixed charge hydrogen engines features increased losses compared to other fuels such as methane. Most studies attribute this higher loss to increased rates of heat transfer from the working fluid to the combustion chamber walls. Indeed, heat flux measurements during combustion and expansion recorded much higher values for hydrogen compared to methane stoichiometric operation. With regard to fluid properties, using the same net heat release equation as for gasoline engines results in an over prediction of heat losses to the combustion chamber walls. Also, the variation of specific heats ratio greatly influences calculated values for the rate of heat release. Therefore, a more detailed analysis of heat losses is required when comparing hydrogen to other fuels.
2012-09-10
Journal Article
2012-01-1642
William Imoehl, Luca Gestri, Marco Maragliulo, Licia Del-Frate, Manfred Klepatsch, Ray Wildeson
A series of designed experiments (DOE) was used to optimize the seat and orifice designs in a multi stream gasoline direct injector. The goal of the experiments was to minimize the effects of fuel deposits on the injector performance. Two different engines were used in the test campaign. One engine, a centrally injected turbocharged 1.6L four cylinder, was used to run a three factor full factorial DOE that tested the effects of SAC volume design, tip design and combustion seal position. Another, a centrally injected turbocharged 3.0L six cylinder, was used to run a three factor full factorial and a four factor half factorial DOE. The three factors in the full factorial were orifice hole divergence, orifice hole surface finish and the use of an inert amorphous silicon coating. A fourth factor, hydro erosive grinding of the orifice holes, was added to facilitate the calculation of a four factor half factorial DOE with only four additional engine tests.
2012-09-10
Journal Article
2012-01-1643
Magnus Sjöberg, David Reuss
The lean-burn stratified-charge DISI engine has a strong potential for increased thermal efficiency compared to the traditional throttled SI engine. This experimental study of a spray-guided stratified-charge combustion system compares the engine response to injection-timing retard for gasoline and E85. Focus is on engine-out NO and soot, and combustion stability. The results show that for either fuel, injection-timing retard lowers the engine-out NO emissions. This is partly attributed to a combination of lower peak-combustion temperatures and shorter residence time at high temperatures, largely caused by a more retarded combustion phasing. However, for the current conditions using a single-injection strategy, the potential of NO reduction with gasoline is limited by both elevated soot emissions and the occurrence of misfire cycles. In strong contrast, when E85 fuel is used, the combustion system responds very well to injection-timing retard.
2012-09-10
Technical Paper
2012-01-1682
Gautam S. Chandekar, Richard D. Hercamp, Doug Hudgens
Cavitation, the study of formation, growth, and collapse of vapor cavities in the coolant jacket adjacent to diesel engine cylinder liners is an area of concern for diesel engine builders and users. Prior experimental work provides insight into parameters such as temperature and pressure. A commonly used bench test has been found not to correlate well with field testing. Also, field testing is very time consuming and costly. The 250 hour engine dynamometer coolant test in the industry costs over $60,000. Therefore, use of mathematical models for sorting out coolants is used, to study effects of coolant properties such as viscosity and surface tension on liner cavitation. Jet velocity at the time of implosion of the bubble is considered as a mechanism to quantify cavitation damage potential near a rigid wall. A model calculating jet velocity at the time of bubble collapse near a finite plate is determined using a commercial boundary element code, 2DynaFS.
2012-09-10
Journal Article
2012-01-1680
Simon Bjerkborn, Karin Frojd, Cathleen Perlman, Fabian Mauss
This paper reports on a turbulent flame propagation model combined with a zero-dimensional two-zone stochastic reactor model (SRM) for efficient predictive SI in-cylinder combustion calculations. The SRM is a probability density function based model utilizing detailed chemistry, which allows for accurate knock prediction. The new model makes it possible to - in addition - study the effects of fuel chemistry on flame propagation, yielding a predictive tool for efficient SI in-cylinder calculations with all benefits of detailed kinetics. The turbulent flame propagation model is based on a recent analytically derived formula by Kolla et al. It was simplified to better suit SI engine modelling, while retaining the features allowing for general application. Parameters which could be assumed constant for a large spectrum of situations were replaced with a small number of user parameters, for which assumed default values were found to provide a good fit to a range of cases.
2012-09-10
Technical Paper
2012-01-1679
Rita Di Gioia, Domenico Papaleo, Fabio Massimo Vicchi, Nicolo Cavina
Recent and forthcoming fuel consumption reduction requirements and exhaust emissions regulations are forcing the development of innovative and particularly complex intake-engine-exhaust layouts. In the case of Spark Ignition (SI) engines, the necessity to further reduce fuel consumption has led to the adoption of direct injection systems, displacement downsizing, and challenging intake-exhaust configurations, such as multi-stage turbocharging or turbo-assist solutions. Further, the most recent turbo-GDI engines may be equipped with other fuel-reduction oriented technologies, such as Variable Valve Timing (VVT) systems, devices for actively control tumble/swirl in-cylinder flow components, and Exhaust Gas Recirculation (EGR) systems. Such degree of flexibility has a main drawback: the exponentially increasing effort required for optimal engine control calibration.
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