Mixture Nonuniformity Effects on S.I. Engine Combustion Variability

Sztenderowicz, Mark L.; Heywood, John B.

doi:10.4271/902142

Cited by 30 publications

(4 citation statements)

References 24 publications

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“…One of the common techniques of analysis of the dynamical behaviour of engines is constituted by using a massfraction-burned calculation versus crank angle θ. During a cycle, the burning process is then usually separated in four phases [1] as follows (i) the flame initiation associated with the angular range corresponding to a burned mass fraction (BMF) up to 2%. During this phase, the burning process is not detected by analyzing the cylinder pressure (ii) the flame development associated with burned mass fractions in the range 2% ≤ BMF ≤ 10%.…”

Section: Divergence Rate and Burning Eventsmentioning

confidence: 99%

“…By computing a divergence rate between different pressure cycles versus crank angle, four phases during the combustion cycle are exhibited. These four phases may be identified with the four common phases evidenced by burn rate calculations [1]. Starting from phase portraits and using Poincaré sections, we also study correlations between peak pressures, IMEP and the durations from ignition to appearance of a flame kernel.…”

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confidence: 97%

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Use of the Nonlinear Dynamical System Theory to Study Cycle-to-Cycle Variations from Spark Ignition Engine Pressure Data

Letellier¹,

Meunier-Guttin-Cluzel²,

Gouesbet³

et al. 1997

SAE Technical Paper Series

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Cycle-to-cycle variations in the pressure evolution within the cylinder of a spark ignition engine has long been recognized as a phenomenon of considerable importance. In this work, use of tools borrowed to the nonlinear dynamical system theory to investigate the time evolution of the cylinder pressure is explored. By computing a divergence rate between different pressure cycles versus crank angle, four phases during the combustion cycle are exhibited. These four phases may be identified with the four common phases evidenced by burn rate calculations [1]. Starting from phase portraits and using Poincaré sections, we also study correlations between peak pressures, IMEP and the durations from ignition to appearance of a flame kernel. Accounting for the fact that, during the ignition phase of the combustion cycle, trajectories in a plane projection of the reconstructed phase portrait associated with cycles in the case of motored engine cannot be distinguished from trajectories corresponding to combustion cycles, we estimate the duration of the ignition phase without any prior assumption on the combustion processes. Fluctuations of ignition phase lengths have been found to be correlated with IMEP standard deviations.

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Section: Divergence Rate and Burning Eventsmentioning

confidence: 99%

mentioning

confidence: 97%

Use of the Nonlinear Dynamical System Theory to Study Cycle-to-Cycle Variations from Spark Ignition Engine Pressure Data

Letellier¹,

Meunier-Guttin-Cluzel²,

Gouesbet³

et al. 1997

SAE Technical Paper Series

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“…Mixing within the cylinder may also have an effect. Sztenderowicz and Heywood demonstrate that in-cylinder inhomogeneity of a stoichiometric gasoline/air mixture produces a slight increase in the standard deviation of the flame initiation and development, but no significant impact on overall bum |, duration or indicated mean effective pressure (IMEP) [SH90]. To date, however, similar tests have not been conducted with natural gas mixtures.…”

Section: Cylinder-to-cylinder Mixingmentioning

confidence: 99%

Evaluation of aftermarket fuel delivery systems for natural gas and LPG vehicles

Willson

1992

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On September 16, 1991 theSolar Energy Institute was designateda nationallaboratory,and its name was changed to the National Renewable Energy Laboratory. NOTICFThis report was prepared as an accountofworksponsoredbyan agencyof the UnitedStatesgovernment, Neitherthe UnitedStatesgovernmentnor anyagencythereof,nor anyof theiremployees, makesany warranty,expressor implied, or assumesany legalliabilityor responsibility forthe accuracy, completeness, or usefulnessof anyinformation, apparatus,product, or processdisclosed, or representsthat itsuse wouldnotinfringeprivatelyowned rights.Reference herein to any srecificcommercialproduct,process,or service by tradename, trademark,manufacturer,or otherwisedoesnot necessarily constituteor implyitsendorsement, recommendation,or favoringbythe UnitedStatesgovernmentor any agencythereof.The viewsand opinionsof authorsexpressedhereindo notnecessarilystate or reflectthoseof the UnitedStatesgovernmentor any agencythereof. Price:Microfiche A01 PrintedCopy A05Codesare usedforpricingali publications. Thecodeis determinedbythenumberofpagesinthe publication. Information pertainingtothe pricingcodes can be found in the currentissue of the followin2publicationswhich are generallyavailablein most libraries:Energy Research Abstracts (ERA); Government Reports AnnouncementsandIndex(G/:_ and I);Scientific and Technica/AbstractReports(STAR);and publication NTIS.PR-360 available from NTIS at the above address. ! PrefaceThis study was designed to evaluate the effectiveness of aftermarket fuel delivery systems for vehicles fueled by compressed natural gas (CNG) and liquefied petroleum gas (LPG). Most of the CNG and LPG vehicles studied were converted to the alternative fuel after purchase. There are wide variations in the quality of the conversion hardware and the installation. This leads to questions about the overall quality of the converted vehicles, in terms of emissions, safety, and performance. "lhere is a considerable body of emissions data for converted light-duty vehicles, and a smaller amount for medium-and heavy-duty vehicles. However, very few of these data involve real world conditions, and there is growing concern about in-use emissions. This report also attempts to assess factors that could allow in-use emissions to vary from the "best-case" results normally reported. The study also addresses issues of fuel supply, fuel composition, performance, saiety, and warranty waivers. The report is based on an extensive literature and product survey and on the author's experience with fuel delivery systems for light-duty vehicles.I would like to thank several people for their contributions to the project. Mr. Bradley Cohen assisted with the literature _arch.A study was undertaken to evaluate the effectiveness of aftermarket fuel delivery systems for compressed natural gas (CNG) and liquefied petroleum gas (LPG). 'Ibis involved a detailed literature and product review to evaluate the performance, emissions, drivability, and safety of vehicles fueled by CNG or LPG.Currently, there are more than 50...

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“…In 1990, Sztenderowicz and Heywood [22] studied cycle-to-cycle combustion variability in a single cylinder research engine (Ricardo Hydra Mk III) and how it is influenced by spatial nonhomogeneity in the unburned mixture. They chose two mixture-nonhomogeneity cases: a typical nonhomogeneous mixture obtained with port fuel injection of indolene, and a perfect mixture of premixed isooctane prepared in a mixing tank before entering the combustion chamber.…”

Section: Introductionmentioning

confidence: 99%

Spark ignited turbulent flame kernel growth. Annual report, January--December, 1992

Santavicca¹

1994

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Results from an experimental study of the effect of incomplete fuel-air mixing on spark-ignited flame kernel growth in turbulent propane-air mixtures are presented. The experiments were conducted in a turbulent flow system that allows for independent variation of flow parameters, ignition system parameters, and the degree of fuel-air mixing. Measurements were made at I atm and 300 K conditions. Five cases were studied; a premixed and four incompletely mixed cases with 6°1o,13%, 24% and 33% RMS (root-mean-square) fluctuations in the fuel/air equivalence ratio. The overall fuel/air equivalence ratio was unity in all cases. The flow characteristics were measured by LDV. The RMS fluctuation in the fuel/air equivalence ratio was characterized using NOrbased laser induced fluorescence. High speed laser shadowgraphy at 4,000 frames-per-second was used to record flame kernel growth following spark ignition, from which the equivalent flame kernel radius as a function of time was determined. The effect of incomplete fuel-air mixing was evaluated in terms of the flame kernel growth rate, "cyclic" variations in the flame kernel growth, and the rate of misfire. The results show that fluctuations in local mixture strength due to incomplete fuel-air mixing cause the flame kernel surface to become wrinkled and distorted; and that the amount of wrinkling increases as the degree of incomplete fuel-air mixing increases. Incomplete fuel-air mixing was also found to result in a significant increase in "cyclic" variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed caseswere found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate is significantly lower. The premixed and 6%-RMS-fluctuation cases had a O°Iomisfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24%-RMS-fluctuation cases, respectively; however, it drastically increased to 23°Io in the 33%-RMS-fluctuation case.

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Mixture Nonuniformity Effects on S.I. Engine Combustion Variability

Cited by 30 publications

References 24 publications

Use of the Nonlinear Dynamical System Theory to Study Cycle-to-Cycle Variations from Spark Ignition Engine Pressure Data

Use of the Nonlinear Dynamical System Theory to Study Cycle-to-Cycle Variations from Spark Ignition Engine Pressure Data

Evaluation of aftermarket fuel delivery systems for natural gas and LPG vehicles

Spark ignited turbulent flame kernel growth. Annual report, January--December, 1992

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