A Study of Volumetric Ignition Using High-Speed Plasma for Improving Lean Combustion Performance in Internal Combustion Engines

Shiraishi, Taisuke; Kakuho, Akihiko; Urushihara, Tomonori; Cathey, Charles; Tang, Tao; Gundersen, M.A.

doi:10.4271/2008-01-0466

Cited by 34 publications

(5 citation statements)

References 9 publications

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“…Several different methods have been proposed to achieve stable lean well-mixed operation, such as high-energy ignition, multiple SI, plasma ignition, and microwave-assisted ignition. 3–5,10–14 These strategies have shown engine performance improvements in certain engine speed/load ranges by creating a larger effective flame kernel and/or a longer kernel lifetime. 11 There are also torch-ignition systems that utilize a pre-chamber to produce flame jets in the main combustion chamber.…”

Section: Introductionmentioning

confidence: 99%

The use of partial fuel stratification to enable stable ultra-lean deflagration-based Spark-Ignition engine operation with controlled end-gas autoignition of gasoline and E85

Zhang

Sjöberg

et al. 2019

International Journal of Engine Research

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Lean operation of Spark-Ignition engines can provide higher thermal efficiency compared to standard stoichiometric operation. However, for a homogeneous lean mixture, the associated reduction of flame speeds becomes an important issue from the perspective of robust ignition and fast flame spread throughout the charge. This study is focused on the use of a lean partial fuel stratification strategy that can stabilize the deflagration, while sufficiently fast combustion is ensured via the use of end-gas autoignition. The engine has a spray-guided Direct-Injection Spark-Ignition combustion system and was fueled with either a high-octane certification gasoline or E85. Partial fuel stratification was achieved using several fuel injections during the intake stroke in combination with a small pilot-injection concurrent with the Spark-Ignition. The results reveal that partial fuel stratification enables very stable combustion, offering higher thermal efficiency for parts of the load range in comparison to well-mixed lean and stoichiometric combustion. The heat release and flame imaging demonstrate that the combustion often has three distinct stages. The combustion of the pilot-injected fuel, ignited by the normal spark, acts as a “super igniter,” ensuring a very repeatable initiation of combustion, and flame incandescence reveals locally rich conditions. The second stage is mainly composed of blue flame propagation in a well-mixed lean mixture. The third stage is the compression autoignition of a well-mixed and typically very lean end-gas. The end-gas autoignition is critical for achieving high combustion efficiency, high thermal efficiency, and stable combustion. Partial fuel stratification enables very effective combustion-phasing control, which is critical for controlling the occurrence and intensity of end-gas autoignition. Comparing the gasoline and E85 fuels, it is noted that achieving end-gas autoignition for the higher octane E85 requires a more aggressive compression of the end-gas via the use of a more advanced combustion phasing or higher intake-air temperature.

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Section: Introductionmentioning

confidence: 99%

The use of partial fuel stratification to enable stable ultra-lean deflagration-based Spark-Ignition engine operation with controlled end-gas autoignition of gasoline and E85

Zhang

Sjöberg

et al. 2019

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…Many studies of ignition have been undertaken, addressing not only the improvement of conventional SI [8][9][10][11] but also the application of non-thermal equilibrium ignition using nanosecond pulses [12][13][14][15][16][17] and microwave discharge. [18][19][20] Despite the number of studies addressing conventional SI, however, the flow of energy from the spark discharge to the initial flame propagation has never been fully explained.…”

Section: Introductionmentioning

confidence: 99%

“…The spark-discharge plasma has been assumed to be in thermal equilibrium, where the electronic, vibrational, rotational, and translational temperatures are all approximately equal. 12 Some studies have attempted to measure the temperature in the spark-discharge plasma. [29][30][31][32][33] Astanei et al determined the vibrational temperature from the N 2 emissions and the rotational temperature from the OH emissions in the spark-discharge plasma.…”

Section: Introductionmentioning

confidence: 99%

Measurement of vibrational and rotational temperature in spark-discharge plasma by optical emission spectroscopy: Change in thermal equilibrium characteristics of plasma under air flow

Kinoshita

Fuyuto

Akatsuka

2018

International Journal of Engine Research

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The vibrational and rotational temperatures in a spark-discharge plasma were measured using optical emission spectroscopy, and the influence of the air flow velocity and ambient pressure on these temperatures was investigated. The optical emissions from the plasma were led to an imaging spectroscope through an optical fiber. The temperature was estimated by fitting a theoretically calculated spectrum to that which had been acquired experimentally, formed by nitrogen molecule emission from 372 to 382 nm. The spark-discharge plasma was examined with a flow of ambient air at a discharge energy of 80 mJ. The air flow caused the spark-discharge channel to elongate downstream. At the center of the spark plug gap, the vibrational temperature in the plasma was 4000 K, whereas the rotational temperature was 2000 K. This plasma can be regarded as being in non-thermal equilibrium because the vibrational temperature was higher than the rotational temperature. At a position approximately 3 mm downstream from the spark plug gap, the vibrational and rotational temperatures increased to 4500 and 4000 K, respectively, while approaching each other. Both temperatures reached a maximum value. These results show that the plasma transitions from non-thermal equilibrium to thermal equilibrium as it is elongated by the air flow. Ignition efficiency improvements can be expected if the time required to transition from non-thermal to thermal equilibrium can be shortened.

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“…The discharge takes a multi-channel pattern and heats up if sustained with high voltage, reaching ignition temperatures. The mechanisms of non-equilibrium plasma for ignition and combustion have been examined in depth in [32,33].I n [34] high-speed pulsed plasma is generated in a coaxial electrode system producing a volumetric discharge. Authors found that, adopting the high-speed pulsed plasma ignition system, the flame development angle reduces and the mixture ignitability improves, in particular under lean combustion conditions, compared with the conventional spark plug.…”

Section: Introductionmentioning

confidence: 99%

Radio frequency spark plug: An ignition system for modern internal combustion engines

Mariani

Foucher

2014

Applied Energy

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A Study of Volumetric Ignition Using High-Speed Plasma for Improving Lean Combustion Performance in Internal Combustion Engines

Cited by 34 publications

References 9 publications

The use of partial fuel stratification to enable stable ultra-lean deflagration-based Spark-Ignition engine operation with controlled end-gas autoignition of gasoline and E85

The use of partial fuel stratification to enable stable ultra-lean deflagration-based Spark-Ignition engine operation with controlled end-gas autoignition of gasoline and E85

Measurement of vibrational and rotational temperature in spark-discharge plasma by optical emission spectroscopy: Change in thermal equilibrium characteristics of plasma under air flow

Radio frequency spark plug: An ignition system for modern internal combustion engines

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