Detailed Simulations of Stratified Ignition and Combustion Processes in a Spray-Guided Gasoline Engine using the SparkCIMM/G-Equation Modeling Framework

Dahms, Rainer N.; Drake, Michael C.; Grover, Ronald O.; Solomon, A. S. P.; Fansler, Todd D.

doi:10.4271/2012-01-0132

Cited by 16 publications

(11 citation statements)

References 38 publications

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“…44 Although the mathematical derivation of the variance equation has been questioned in Lipatnikov and Sabel’nikov, 49 and a significant under-prediction of the mean flame brush thickness was reported in Herrmann, 27 the G -equation framework has nonetheless shown considerable success when applied to IC engine combustion in previous studies. 26,50–56 Since detailed investigations into G variance modelling are well beyond the scope of the present investigation, the default formulation has therefore been adopted in this study.…”

Section: Methodsmentioning

confidence: 99%

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Wright

Schiliro

et al. 2018

International Journal of Engine Research

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Prechamber ignition technology receives increasing attention due to its considerable improvement on engine combustion efficiency and stability. However, fundamental knowledge concerning flame propagation inside the pre-chamber and jet formation in the main chamber is still quite scarce. In this study, a small (<0.5% VTDC) un-scavenged pre-chamber was tested in a medium size gas engine with pressure transducers installed in both pre- and main chamber. Three-dimensional computational reactive fluid dynamics Reynolds-averaged Navier–Stokes simulations were carried out using a level-set combustion model –G-equation – towards improved understanding of the combustion processes occurring inside the pre and main chamber. The characteristics of the turbulence and the flame at locations just ahead of the propagating turbulent flame front were recorded and analysed by means of the well-known Borghi–Peters diagram. The results revealed that the characteristics of the flame inside the pre-chamber differed greatly from those inside the main chamber due to considerably reduced turbulent length scales. In addition, a wide range of turbulence intensity and length scales are covered throughout the combustion event, presenting a significant challenge to modelling of flame–turbulence interaction. Various turbulent flame speed ( ST) closures widely used in internal combustion engine simulation were therefore assessed and the ranges of their respective model constants explored. A correlation for ST is subsequently proposed by blending two formulations of Gülder developed for small and large scale turbulence, respectively, and compared to the well-known Peters correlation. With appropriate model constants, both successfully reproduce the pre and main chamber combustion for the reference case in terms of evolutions of cylinder pressure, heat release rate and pressure difference between pre and main chamber. Following successful calibration of the reference operating condition, variations in engine speed, load, spark timing and lambda were calculated using both correlations, demonstrating encouraging predictive capabilities of the proposed modelling strategy.

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Section: Methodsmentioning

confidence: 99%

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Wright

Schiliro

et al. 2018

International Journal of Engine Research

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“…Particularly, the importance to include turbulence and mixture fraction fluctuations in modeling the development of the flame kernel by the ignition model was pinpointed. In a later study [137], a deeper investigation was done on a GDI engine operating at different engine speeds, loads, EGR, injection and spark timings. Excellent agreement was achieved between computed and measured pressure curves, heat release rates, characteristic burn points and combustion efficiencies.…”

Section: Spray Mixture Formation and Combustion Modelingmentioning

confidence: 99%

“…Recent computational studies on combustion within GDI engine configurations have incorporated reduced chemical kinetic mechanisms to better represent the chemistry of gasoline fuels in computing the laminar flame speeds. Nonetheless, the mechanisms applied are restricted to those of single component iso-octane [132], [138], [141] and binary blends of PRF [120], [134], [137]. Hence, complex reaction mechanisms with multiple fuel components should be merged with combustion modeling works in GDI engines while significant efforts need to be directed at improving the current predictive capability of combustion models across a wide range of operating conditions.…”

Section: Spray Mixture Formation and Combustion Modelingmentioning

confidence: 99%

Developments in computational fluid dynamics modelling of gasoline direct injection engine combustion and soot emission with chemical kinetic modelling

Tan¹,

Bonatesta²,

Ng³

et al. 2016

Applied Thermal Engineering

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Designed to inject gasoline fuel directly into the combustion chamber, gasoline direct injection (GDI) combustion systems are gaining popularity among the automotive industry. This is because GDI engines offer less pumping and heat losses, enhanced fuel economy and improved transient response. Nonetheless, the technology is often associated with the emission of ultra-fine particulate matter (PM) to the atmosphere. With the increasingly stringent emission regulations, detailed understanding of PM formation within GDI engine configurations is very crucial. To complement the findings based on experimental and optical techniques, computational fluid dynamics (CFD) modeling has been widely utilized to study the in-cylinder physical and chemical events. The success of CFD simulations also requires an accurate representation of gasoline fuel kinetics. Set against the background, the present review reports on the recent developments in chemical kinetic modeling of gasoline fuels and CFD numerical studies for GDI engines emphasizing the combustion and emission stages. Regarding fuel kinetics, the use of primary reference fuel (PRF) and ternary reference fuel (TRF) mechanisms is evaluated. In addition, the current trend portrays a progression towards multi-component surrogate models to account for the complex mixture of practical fuels. It is however observed that many reaction mechanisms proposed in the literature are validated under homogeneous charge compression ignition (HCCI) engine conditions rather than GDI-related ones. CFD modeling of GDI engines typically covers the simulations of spray, mixture formation and combustion processes. Progress in combustion modeling for both homogeneous and stratified charge modes is discussed thoroughly. Still in its infancy, soot modeling studies for GDI engines are reviewed in which several soot models adapted are appraised. The majority of soot models have been previously applied in diesel combustion systems and flame configurations. Significant efforts are currently carried out to improve the model predictions of soot emission from GDI engines.

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“…Such phenomena have been demonstrated to occur in various systems, such as those that involve the injection of liquid nitrogen or oxygen into environments composed of nitrogen, helium, hydrogen, or argon [3,4,5]. Many works have served to corroborate these observations [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36].…”

Section: Introductionmentioning

confidence: 96%

Liquid jet breakup regimes at supercritical pressures

Dahms

Oefelein

2015

Combustion and Flame

Self Cite

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Previously, a theory has been presented that explains how discrete vapor-liquid interfaces become diminished at certain high-pressure conditions in a manner that leads to well known qualitative trends observed from imaging in a variety of experiments. Rather than surface tension forces, transport processes can dominate over relevant ranges of conditions. In this paper, this framework is now generalized to treat a wide range of fuel-oxidizer combinations in a manner consistent with theories of capillary flows and extended corresponding states theory. Different flow conditions and species-specific molecular properties are shown to produce distinct variations of interfacial structures and local free molecular paths. These variations are shown to occur over the operating ranges in a variety of propulsion and power systems. Despite these variations, the generalized analysis reveals that the envelope of flow conditions at which the transition from classical sprays to diffusion-dominated mixing occurs exhibits a characteristic shape for all liquid-gas combinations. For alkane-oxidizer mixtures, it explains that these conditions shift to higher pressure flow conditions with increasing carbon number and demonstrates that, instead of widely assumed classical spray atomization, diffusion-dominated mixing may occur under relevant high-pressure conditions in many modern devices.

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Detailed Simulations of Stratified Ignition and Combustion Processes in a Spray-Guided Gasoline Engine using the SparkCIMM/G-Equation Modeling Framework

Cited by 16 publications

References 38 publications

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Developments in computational fluid dynamics modelling of gasoline direct injection engine combustion and soot emission with chemical kinetic modelling

Liquid jet breakup regimes at supercritical pressures

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