A Comprehensive Model to Predict the Initial Stage of Combustion in SI Engines

Lucchini, Tommaso; Cornolti, Luca; Montenegro, Gianluca; D’Errico, Gianluca; Fiocco, Marco; Teraji, Atsushi; Shiraishi, Taisuke

doi:10.4271/2013-01-1087

Cited by 60 publications

(45 citation statements)

References 24 publications

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“…The transition to fully developed turbulent flame occurred when the flame kernel is large enough to be resolved by Eulerian grid. In a similar manner, Lucchini et al 14 proposed to place a set of Lagrangian particles as multiple flame kernels along the spark channel. Exponential transition from laminar to turbulent flame was assumed.…”

Section: Introductionmentioning

confidence: 99%

A semi-empirical laminar-to-turbulent flame transition model coupled with G equation for early flame kernel development and combustion in spark-ignition engines

Keum

Zhu

Grover

et al. 2019

International Journal of Engine Research

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It has been reported that early combustion in a spark-ignition engine determines the subsequent combustion. Also, the early combustion has a very strong correlation with cycle-to-cycle variability, which limits engine operating range. As such, accurate modeling of the early flame development is very important in accurate simulation of spark-ignition engine combustion. During the early flame development, the flame kernel, initiated by spark, grows initially at laminar flame speed. As the kernel grows, the flame surface wrinkles due to surface instability and interacts with the flow turbulence as the flame transitions from laminar to turbulent flame. In this study, a semi-empirical model is proposed to simulate the laminar-to-turbulent flame transition process during early spark-ignition combustion. A hyperbolic tangent function was used to emulate the laminar-to-turbulent flame speed transition process. The proposed transition function was evaluated during early flame kernel development for both Reynolds-averaged Navier–Stokes and large eddy simulation models against combustion analysis data from high-speed optical particle image velocimetry. Difference in Reynolds-averaged Navier–Stokes and large eddy simulation transition function was analyzed and discussed.

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Section: Introductionmentioning

confidence: 99%

A semi-empirical laminar-to-turbulent flame transition model coupled with G equation for early flame kernel development and combustion in spark-ignition engines

Keum

Zhu

Grover

et al. 2019

International Journal of Engine Research

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“…To date, an experimental study by Herweg et al 18 is often referenced for the development and validation of ignition models for a flowing mixture. 17,[19][20][21] They developed a unique swirl chamber which can optically capture the behavior of flames near the spark plug in a flowing mixture at high temperatures and pressures equivalent to those of SI engines. In experiments with a transistorized coil ignition (TCI) system, the flames were held behind the spark plug for every measured mixture of l = 1.0, 1.3, and 1.5 at a flow velocity near the spark plug of 30 m/s.…”

Section: Introductionmentioning

confidence: 99%

“…However, in the model devised by Dahms et al, 15,16 the spark channels are shortened when the length of the spark channels exceeds a certain threshold value. Also, the model devised by Lucchini et al 17 provides the thresholds for both the electric potential difference across the spark channels and the lengths of the spark channels. The prediction performance of these ignition models strongly depends on what threshold values are used under each ignition condition.…”

Section: Introductionmentioning

confidence: 99%

Spark ignition and early flame development of lean mixtures under high-velocity flow conditions: An experimental study

Sayama

Kinoshita

Mandokoro

et al. 2018

International Journal of Engine Research

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This study set out to experimentally investigate spark ignition and the subsequent early flame development of lean airfuel mixtures of A/F = 20-30 under high-velocity flow conditions using a uniquely designed swirl chamber. The swirl chamber realizes a high-velocity flow of 65 m/s at the spark plug gap, as well as internal temperature and pressure histories that are equivalent to those of spark-ignition engines, being equipped with an optically accessible engine. The designed swirl chamber clearly captures the characteristic behavior of the spark channels and flames in the vicinity of the spark plug. The results show that the spark channels stretch downstream following the flow and are subject to short circuits or restrikes. In the case of a high ignition energy of 200 mJ, short circuits of the spark channels occur in the early part of the discharge, while restrikes occur in the later parts. With a decrease in the ignition energy, restrikes occur in the earlier parts of the discharge. With a low ignition energy of 65 mJ, restrikes can occur immediately after the electrical breakdown without any significant spark stretch. At a sufficiently low dilution degree of A/F = 20, flames can hold behind the ground electrode of the spark plug, which significantly suppresses the cycle dispersion while also enhancing the combustion in the early stage. With further air dilution, that is, A/F. 20, flames develop, flowing downstream without flame holding. However, temporal flame attachment to the ground electrode is observed during the discharge duration even at A/F = 30, while the attached flames eventually blow off downstream at the end of the spark discharge.

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“…It could not be concluded from this study therefore whether the propagation differences were due to the flame stretch response rather than to a laminar flame speed ranking. Most CFD models require the unstretched laminar burning speed SL 0 [5,7,8,28], often calculated by using correlations such as those of Metghalchi and Keck [29] [30]. However, only a few models take into account the laminar flame speed dependence on the flame stretch with respect to the Markstein length or the Lewis number of the fuel-air mixture and use a stretched burning speed [6,7,9,10,31].…”

Section: Introductionmentioning

confidence: 99%

Fuel performances in Spark-Ignition (SI) engines: Impact of flame stretch

Bréquigny

Halter

Mounaïm‐Rousselle

et al. 2016

Combustion and Flame

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International audienceIn a context of decreasing pollutant emissions, the transport sector has to tackle improvements to the engine concept as well as fuel diversification. The use of these different fuels often has an impact on the combustion performance itself. In the case of Spark Ignition (SI) engines, efficiency is a function of the combustion speed, i.e. the speed at which the fresh air–fuel mixture is consumed by the flame front. Every expanding flame is subject to flame curvature and strain rate, which both contribute to flame stretch. As each air–fuel mixture responds differently to flame stretch, this paper focuses on understanding the impact of flame stretch on fuel performances in SI engines. Different air–fuel mixtures (different fuels or equivalence ratios) with similar unstretched laminar burning speeds and thermodynamic properties but different responses to stretch were selected. The mixtures were studied in a turbulent spherical vessel and in an optical engine using Mie-Scattering tomography. The combustion phasing was also investigated in both optical and all-metal single cylinder engines. Results show that flame stretch sensitivity properties such as Markstein length and Lewis number, determined in laminar combustion conditions, are relevant parameters that need to be taken into consideration to predict the global performance of fuels, either experimentally or for modeling simulation

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A Comprehensive Model to Predict the Initial Stage of Combustion in SI Engines

Cited by 60 publications

References 24 publications

A semi-empirical laminar-to-turbulent flame transition model coupled with G equation for early flame kernel development and combustion in spark-ignition engines

A semi-empirical laminar-to-turbulent flame transition model coupled with G equation for early flame kernel development and combustion in spark-ignition engines

Spark ignition and early flame development of lean mixtures under high-velocity flow conditions: An experimental study

Fuel performances in Spark-Ignition (SI) engines: Impact of flame stretch

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