Validation of a Turbulent Flame Propagation Model for a Spark Ignition Engine

Improved internal combustion engine simulations of natural gas (NG) combustion under conventional and advanced combustion strategies have the potential to increase the use of NG in the transportation sector in the U.S. This study focused on the physics of turbulent flame propagation. The experiments were performed in a single-cylinder heavy-duty compression-ignition (CI) optical engine with a bowl-in piston that was converted to spark ignition (SI) NG operation. The size and growth rate of the early flame from the start of combustion (SOC) until the flame filled the camera field-of-view were correlated to combustion parameters determined from in-cylinder pressure data, under low-speed, lean-mixture, and medium-load conditions. Individual cycles showed evidence of turbulent flame wrinkling, but the cycle-averaged flame edge propagated almost circular in the two-dimensional (2D) images recorded from below. More, the flame-speed data suggested different flame propagation inside a bowl-in piston geometry compared to a typical SI engine chamber. For example, while the flame front propagated very fast inside the piston bowl, the corresponding mass fraction burn was small, which suggested a thick flame region. In addition, combustion images showed flame activity after the end of combustion (EOC) inferred from the pressure trace. All these findings support the need for further investigations of flame propagation under conditions representative of CI engine geometries, such as those in this study.

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Investigation of Flame Propagation Description in Quasi-Dimensional Spark Ignition Engine Modeling

10.4271/2018-01-1655 ◽

2018 ◽

Cited By ~ 3

Author(s):

Simon Malcher ◽

Michael Bargende ◽

Michael Grill ◽

Ulrich Baretzky ◽

Hartmut Diel ◽

...

Keyword(s):

Flame Propagation ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Engine Modeling

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Swirl effect on the flame propagation at idle in a spark ignition engine

KSME International Journal ◽

10.1007/bf03191926 ◽

2000 ◽

Vol 14 (12) ◽

pp. 1412-1420 ◽

Cited By ~ 2

Author(s):

Shin Hyuk Joo ◽

Kwang Min Chun ◽

Younggy Shin

Keyword(s):

Flame Propagation ◽

Spark Ignition ◽

Spark Ignition Engine

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Early flame propagation in a spark-ignition engine measured with quasi 4D-diagnostics

Proceedings of the Combustion Institute ◽

10.1016/j.proci.2014.05.131 ◽

2015 ◽

Vol 35 (3) ◽

pp. 3829-3837 ◽

Cited By ~ 34

Author(s):

B. Peterson ◽

E. Baum ◽

B. Böhm ◽

A. Dreizler

Keyword(s):

Flame Propagation ◽

Spark Ignition ◽

Spark Ignition Engine

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Numerical Investigation of Fuel Property Effects on Mixed-Mode Combustion in a Spark-Ignition Engine

ASME 2019 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2019-7265 ◽

2019 ◽

Cited By ~ 1

Author(s):

Chao Xu ◽

Pinaki Pal ◽

Xiao Ren ◽

Sibendu Som ◽

Magnus Sjöberg ◽

...

Keyword(s):

Heat Release ◽

Flame Propagation ◽

Heat Release Rate ◽

Release Rate ◽

Octane Number ◽

Mixed Mode ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Chemical Effect ◽

Auto Ignition

Abstract In the present study, mixed-mode combustion of an E30 fuel in a direct-injection spark-ignition engine is numerically investigated at a fuel-lean operating condition using multidimensional computational fluid dynamics (CFD). A fuel surrogate matching Research Octane Number (RON) and Motor Octane Number (MON) of E30 is first developed using neural network based non-linear regression model. To enable efficient 3D engine simulations, a 164-species skeletal reaction mechanism incorporating NOx chemistry is reduced from a detailed chemical kinetic model. A hybrid approach that incorporates the G-equation model for tracking turbulent flame front, and the multi-zone well-stirred reactor model for predicting auto-ignition in the end gas, is employed to account for turbulent combustion interactions in the engine cylinder. Predicted in-cylinder pressure and heat release rate traces agree well with experimental measurements. The proposed modelling approach also captures moderated cyclic variability. Two different types of combustion cycles, corresponding to purely deflagrative and mixed-mode combustion, are observed. In contrast to the purely deflagrative cycles, mixed-mode combustion cycles feature early flame propagation followed by end-gas auto-ignition, leading to two distinctive peaks in heat release rate traces. The positive correlation between mixed-mode combustion cycles and early flame propagation is well captured by simulations. With the validated numerical setup, effects of NOx chemistry on mixed-mode combustion predictions are investigated. NOx chemistry is found to promote auto-ignition through residual gas recirculation, while the deflagrative flame propagation phase remains largely unaffected. Local sensitivity analysis is then performed to understand effects of physical and chemical properties of the fuel, i.e., heat of evaporation (HoV) and laminar flame speed (SL). An increased HoV tends to suppress end-gas auto-ignition due to increased vaporization cooling, while the impact of HoV on flame propagation is insignificant. In contrast, an increased SL is found to significantly promote both flame propagation and auto-ignition. The promoting effect of SL on auto-ignition is not a direct chemical effect; it is rather caused by an advancement of the combustion phasing, which increases compression heating of the end gas.

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