Turbulence and Turbulent Combustion in Spark-Ignition Engines

Tabaczynski, R. J.

doi:10.1016/b978-0-08-024780-9.50017-4

Cited by 9 publications

(5 citation statements)

References 34 publications

(28 reference statements)

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“…flamefront NO is formed at an equivalence ratio Equation ( 1 and Vranos [38] show a fourfold reduction in flameheight or about one-tenth of the cylinder radius, front NO in a turbulent premixed atmospheric presswhich totally agrees with Tabaczynski's observations ure flame, when the equivalence ratio is reduced [35]. Figure 3 shows that the turbulent flame thickfrom 0.74 to 0.6, whereas Dodge et al claim that the ness is about 5 mm.…”

Section: Computation Of Flamefront No Emissions From Spark Ignition Enginessupporting

confidence: 69%

Computation of flamefront NO emissions from spark ignition engines

Narayan

Rajan

2001

International Journal of Engine Research

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Flamefront NO emissions from spark ignition The Fenimore mechanism [5] is yet another reacengines are estimated in this work using a two-zone thermo-tion pathway that leads to 'prompt' NO formation dynamic combustion model, an unsteady engine flame in a flamefront and also in post-flame gases of very model, the wrinkled laminar flame model of Bray and Moss, rich premixed flames [6]. In all premixed flames, O the k-å theory and simplified flamefront NO chemistry atom concentrations are much above chemical equiwhich has been verified in steady laminar premixed flames. librium levels, augmenting the rates within the The results show that as much as 230 ppm of flamefront NO flamefront of the Zeldovich and N 2 O reaction rates may be formed under stoichiometric engine operating con-[6]. Flamefront NO emissions, including Fenimore's ditions. The present approach is an alternative to the empiriprompt NO, from steady laminar methane/air cal correlations used to compute engine flamefront NO flames have been successfully predicted by a number which are based on highly extrapolated data. of workers [6-9], because of exponential increases in computing capabilities and more accurate chemical Key words: flamefront NO emissions, prompt NO, kinetic data. The flamefront NO mechanism in prespark ignition engine, methane fuel, two-zone engine mixed flames is very complex [6], but has recently combustion model been simplified by a number of workers [9, 10]. It is difficult to predict flamefront NO emissions from turbulent flames because turbulent flame codes cannot incorporate more than a few chemical reac-

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Section: Computation Of Flamefront No Emissions From Spark Ignition Enginessupporting

confidence: 69%

Computation of flamefront NO emissions from spark ignition engines

Narayan

Rajan

2001

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…14 and 15, suggesting that swirl and swumble may result in a similar structure of the incylinder fluid motion. Tumble, on the other hand, starts breaking up rapidly near TDC, leading to substantially high turbulence intensity during ignition and then the increased combustion rate [30,31]. The enhanced turbulence results in strong reduction of the burn delay.…”

Section: Discussionmentioning

confidence: 99%

Effect of Intake Primary Runner Blockages on Combustion Characteristics and Emissions with Stoichiometric and EGR-diluted Mixtures in SI Engines

He¹,

Selamet²,

Reese³

et al. 2007

SAE Technical Paper Series

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“…Turbulence intensity u' prior to ignition has a fundamental effect on combustion in SI engines, hence influences the engine performance and exhaust emissions. Much experimental work [1][2][3][4] has demonstrated that the ratio of turbulent flame speed S T to laminar flame speed S L increases nearly linearly with L ' S . u…”

Section: Introductionmentioning

confidence: 99%

Impact of Tumble on Combustion in SI Engines: Correlation between Flow and Engine Experiments

He¹,

Selamet²,

Reese³

et al. 2007

SAE Technical Paper Series

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The introduction of tumble into the combustion chamber is an effective method of enhancing turbulence intensity prior to ignition, thereby accelerating the burn rates, stabilizing the combustion, and extending the dilution limit. In this study, the primary intake runners are partially blocked to produce different levels of tumble motion in the cylinder during the air induction process. Experiments have been performed with a Chrysler 2.4L 4-valve I4 engine at maximum brake torque timing under two operating conditions: 2.41 bar brake mean effective pressure (BMEP) at 1600 rpm, and 0.78 bar BMEP at 1200 rpm. A method has been developed to quantify the tumble characteristics of blockages under steady flow conditions in a flow laboratory, by using the same cylinder head, intake manifold, and tumble blockages from the engine experiments. A refined tumblemeter is installed under cylinder head to measure the compressive load of the tumble vortex, allowing for the calculation of angular momentum of the incoming air, tumble number, and tumble ratio at varying intake valve lifts. A correlation is then sought between the engine and flow experiments to help quantify the impact of tumble motion on combustion and cyclic variation. The air flow rate into the cylinder, discharge coefficient of the intake system, and the flow loss coefficient across the blockage are also analyzed for different levels of tumble motion. The validity of the method under steady flow conditions is confirmed by comparison of the results with the engine experiments.

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Turbulence and Turbulent Combustion in Spark-Ignition Engines

Cited by 9 publications

References 34 publications

Computation of flamefront NO emissions from spark ignition engines

Computation of flamefront NO emissions from spark ignition engines

Effect of Intake Primary Runner Blockages on Combustion Characteristics and Emissions with Stoichiometric and EGR-diluted Mixtures in SI Engines

Impact of Tumble on Combustion in SI Engines: Correlation between Flow and Engine Experiments

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