Analysis of a stratified pre-chamber spark ignition system under lean mixture conditions

The current research experimentally studied flame speed and stretch under engine in-cylinder conditions. A direct-injection, spark-ignition, and optically accessible engine was utilized to image the flame propagation, and E10 was selected as the fuel. Also, three fuel–air mixtures (stoichiometric, lean, and rich) were examined. The flame front was located by processing high-speed images. This study introduces a novel approach for calculation of equivalent spherical flame radius for analysis of flame speed and stretch. Flame front propagation analysis showed that during the flame propagation period, the stretch decreased until the flame front touched the piston surface. This was a common trend for stoichiometric, lean, and rich mixtures, which occurred because the flame radius was the dominant factor in the stretch calculation. In addition, the rich fuel–air mixture showed a lower flame stretch compared to stoichiometric or lean mixture. This was the result of a lower Markstein number for the rich fuel–air mixture. To study the sensitivity of different fuel–air mixtures to the flame stretch, the trajectory of the flame centroid was tracked until the flame front touched the piston surface. The results showed that the end centroid for the lean mixture deviated from the start point more than those of the rich and stoichiometric mixtures because the lean mixture had a higher flame stretch and lower flame speed. Furthermore, comparing the flame stretch at three different engine speeds revealed that increasing the engine speed increased the flame stretch, especially during the early flame development period. According to previous studies which discussed flame stretch as a flame extinguishment mechanism, the probability of flame extinction is higher when the engine speed is higher. Also, uncertainty analysis was conducted to determine the effect of camera setting on the flame stretch. Results showed that a maximum relative uncertainty of 4.5% occurred during the early flame development.

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The Lean Mixture Operational Limits of a Spark Ignition Engine When Operated on Fuel Mixtures

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2978998 ◽

2008 ◽

Vol 131 (1) ◽

Cited By ~ 11

Author(s):

Hailin Li ◽

Ghazi A. Karim ◽

A. Sohrabi

Keyword(s):

Engine Performance ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Si Engine ◽

Lean Mixture ◽

Si Engines ◽

Unstable Combustion ◽

Fuel Mixtures ◽

Traditional Approaches ◽

Combustion Processes

The operation of spark ignition (SI) engines on lean mixtures is attractive, in principle, since it can provide improved fuel economy, reduced tendency to knock, and extremely low NOx emissions. However, the associated flame propagation rates become degraded significantly and drop sharply as the operating mixture is made increasingly leaner. Consequently, there exist distinct operational lean mixture limits beyond which satisfactory engine performance cannot be maintained due to the resulting prolonged and unstable combustion processes. This paper presents experimental data obtained in a single cylinder, variable compression ratio, SI engine when operated in turn on methane, hydrogen, carbon monoxide, gasoline, iso-octane, and some of their binary mixtures. A quantitative approach for determining the operational limits of SI engines is proposed. The lean limits thus derived are compared and validated against the corresponding experimental results obtained using more traditional approaches. On this basis, the dependence of the values of the lean mixture operational limits on the composition of the fuel mixtures is investigated and discussed. The operational limit for throttled operation with methane as the fuel is also established.

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Improvements of ignitability for the series multipoint spark ignition system Tohru Yoshinaga, Hisashi Kawai (Nippon Soken, Inc.), Toshihiko Igashira (Nippondenso Co. Ltd.), Norihiko Nakamura (Toyota Moter Corp), Toshiaki Yano, Takakuni Hirayu (Kagoshima University)

JSAE Review ◽

10.1016/s0389-4304(96)80581-9 ◽

1996 ◽

Vol 17 (4) ◽

pp. 444

Keyword(s):

Spark Ignition ◽

Ignition System

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Evaluation of the Effects of a Twin Spark Ignition System on Combustion Stability of a High Performance PFI Engine

Energy Procedia ◽

10.1016/j.egypro.2015.12.143 ◽

2015 ◽

Vol 81 ◽

pp. 897-906 ◽

Cited By ~ 9

Author(s):

Claudio Forte ◽

Gian Marco Bianchi ◽

Enrico Corti ◽

Stefano Fantoni

Keyword(s):

High Performance ◽

Spark Ignition ◽

Combustion Stability ◽

Ignition System

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Characterization of a Multi-Cylinder Torch Ignition System Operating with Homogenous Charge and Lean Mixture

10.4271/2014-36-0333 ◽

2014 ◽

Cited By ~ 6

Author(s):

T. A. A. MOREIRA ◽

J. G.C. BAETA ◽

F. A. RODRIGUES FILHO ◽

J. E. M BARROS ◽

F. J. P. PUJATTI ◽

...

Keyword(s):

Ignition System ◽

Lean Mixture ◽

System Operating

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Laser Ignition of Natural Gas Engines Using Fiber Delivery

ASME 2005 Internal Combustion Engine Division Fall Technical Conference (ICEF2005) ◽

10.1115/icef2005-1336 ◽

2005 ◽

Cited By ~ 6

Author(s):

Azer P. Yalin ◽

Morgan W. Defoort ◽

Sachin Joshi ◽

Daniel Olsen ◽

Bryan Willson ◽

...

Keyword(s):

Natural Gas ◽

Past Research ◽

Spark Ignition ◽

Laser Source ◽

Laser Ignition ◽

Ignition System ◽

Gas Engine ◽

Natural Gas Engines ◽

Natural Gas Engine ◽

Design Concepts

A practical impediment to implementation of laser ignition systems has been the open-path beam delivery used in past research. In this contribution, we present the development and implementation of a fiber-optically delivery laser spark ignition system. To our knowledge, the work represents the first demonstration of fiber coupled laser ignition (using a remote laser source) of a natural gas engine. A Nd:YAG laser is used as the energy source and a coated hollow fiber is used for beam energy delivery. The system was implemented on a single-cylinder of a Waukesha VGF 18 turbo charged natural gas engine and yielded consistent and reliable ignition. In addition to presenting the design and testing of the fiber delivered laser ignition system, we present initial design concepts for a multiplexer to ignite multiple cylinders using a single laser source, and integrated optical diagnostic approaches to monitor the spark ignition and combustion performance.

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