Investigations on the Effects of the Ignition Spark with Controlled Autoignition (CAI)

Sarikoc, Fatih; Hensel, Sebastian; Han, Kyung-Man; Kubach, Heiko; Spicher, Ulrich

doi:10.4271/2009-01-1770

Cited by 3 publications

(8 citation statements)

References 9 publications

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“…The sensitivity of CAI combustion to spark assistance is heavily dependent on the amount of residual gas trapped. At the highest loads, where increased sensitivity to the spark timing has been previously reported, 3,14 the residual rates can be as low as about 45%. 3 At the lower load limit, where less sensitivity to the spark timing has been found, up to about 80% internal EGR may be trapped.…”

Section: Residual Gas Estimationmentioning

confidence: 81%

“…Under similar residual levels, previous studies of CAI have insinuated that it is not possible to sustain conventional continuous flame propagation from a single source such as the spark, with the reaction developing as a series of zones distributed throughout the chamber and additional zones being triggered in the remaining unburned gases via in-cylinder pressure development. 13,14,39 Ultimately, whether the improvement in combustion stability observed in this work was purely due to increased localised reaction(s) about the spark plug gap cannot be determined without optical engine access.…”

Section: Coil Strike Phasing Effectsmentioning

confidence: 90%

“…38 The aim of the current work was to investigate whether a simple dual-coil system could offer benefits when operating at the cusp of the autoignition limit under low-load ultra-high EGR CAI conditions. Previous optical studies of spark-assisted CAI combustion under similar conditions have shown how highly fragmented reaction zones may co-exist 13,14,39 and the spark may act as a trigger to rapid successive distributed events rather than sustained local flame propagation. Hence it was postulated in the current work that the addition of axial swirl with such a multiple-strike ignition system may help to transfer the burning gases from the plug gap and/or hot-spot locations within the chamber to ensure that additional unburned gas could be ignited after the first coil discharge event.…”

Section: Residual Gas Estimationmentioning

confidence: 99%

“…At higher loads, this is due to the gas exchange and/or the knocking limits and, at lower loads, this arises because the residual gas temperatures are too low to invoke autoignition. In terms of expanding the map, one practical technique relevant to the currently reported work is so-called spark-assisted CAI, [10][11][12][13][14] previously noted to improve the combustion stability and to extend the low-load boundary. For higher loads, supercharging 1,2,4,15,16 has been shown to improve the volumetric efficiency while still allowing sufficient dilution rates and control of the heat release to avoid audible 'knock'.…”

Section: Introductionmentioning

confidence: 99%

“…3,11,13 Conversely, at higher loads there seems to be general agreement of the increased sensitivity to the spark timing, with recent observations of localised flame propagation from the spark when using the blended EGR technique. 3,14 The focus of the currently reported work was to investigate whether a relatively simple ignition system capable of multiple-strike action would be capable of extending the lower-load CAI limit. Specifically, the objective was to investigate whether prolonged or even separated ignition events could provide an increased chance of sustained reaction in the presence of highly fragmented reaction zones under typical high residual CAI conditions.…”

Section: Introductionmentioning

confidence: 99%

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The effects of dual-coil ignition and axial swirl on spark-assisted controlled autoignition

Cairns

Zhang

Dingle

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part D:

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The work involved an experimental study of a dual-coil ignition system for improved combustion stability and control during four-stroke gasoline controlled autoignition combustion. The ignition system was based upon the ‘redundant-coil’ set-up previously used in motorsport applications, where two conventional induction coils are connected to a common spark plug via an individually assigned diode. Such systems have recently been used for improved tolerance to exhaust gas recirculation in automotive spark ignition engines, but their effects have apparently not been previously reported for spark-assisted controlled autoignition. The basis for the work was therefore to validate such operation at low loads, where spark assist has been most widely suggested as a means of stabilising controlled autoignition combustion. The experiments were undertaken using a thermodynamic single-cylinder research engine equipped with an electrohydraulic, fully variable valvetrain on the inlet and the exhaust. This valvetrain was primarily used to invoke negative valve overlap and later, additionally, to allow study of the asymmetric intake valve operation and the influence of the increased axial swirl ratio within the bulk gas flow. The key observation from the work was that a staged single strike per coil strategy was found to improve the combustion stability significantly when operating at the low-load controlled autoignition boundary, especially when combined with increased axial swirl to promote ignitability between successive strikes. Overall, it was concluded that the system provides a new method for ensuring robust controlled autoignition operation at the lowest loads, with additional ability to help to control the combustion noise.

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Section: Residual Gas Estimationmentioning

confidence: 81%

Section: Coil Strike Phasing Effectsmentioning

confidence: 90%

Section: Residual Gas Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The effects of dual-coil ignition and axial swirl on spark-assisted controlled autoignition

Cairns

Zhang

Dingle

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part D:

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Investigation of the potential of corona ignition to control gasoline homogeneous charge compression ignition combustion

Suess

Guenthner

Schenk

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part D:

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A complex task regarding the control of the homogeneous charge compression ignition (HCCI) combustion process is the control of combustion timing, represented by the crank angle at which 50 per cent of the fuel mass inside the cylinder is burned (MFB50). The most important parameters for transient MFB50 control are the mass of (hot) residual gas inside the cylinder (e.g. retained by internal exhaust gas recirculation), the injection strategy (in the case of direct fuel injection), and the spark timing. In this paper, the potential of a corona ignition system is examined in comparison with a conventional spark ignition system for the HCCI combustion process. For this purpose, thermodynamic investigations have been carried out on a single-cylinder research engine, combined with one-dimensional gas exchange analyses and high-speed visualization of combustion in a transparent engine. It could be demonstrated that both ignition systems are capable of influencing the autoignition process. The corona ignition system, however, allows a much later ignition point for achieving the same MFB50. This is due to the spatial character of the initial ignition area of corona ignition. In addition, the corona ignition system is more robust with respect to a change in the boundary conditions, such as a variation in the residual gas rate or the mixture composition. It is therefore more reliable in initiating autoignition, even in critical operating conditions. Additionally, it was found that the corona ignition system permits the combustion to be influenced by means of a variation in the ignition energy, which appeared to be not the case for the conventional ignition system.

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A Study of Combining Gasoline Engine Downsizing and Controlled Auto-Ignition Combustion

Moxey¹,

Cairns²,

Ganippa³

et al. 2015

Journal of KONES. Powertrain and Transport

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Investigations on the Effects of the Ignition Spark with Controlled Autoignition (CAI)

Cited by 3 publications

References 9 publications

The effects of dual-coil ignition and axial swirl on spark-assisted controlled autoignition

The effects of dual-coil ignition and axial swirl on spark-assisted controlled autoignition

Investigation of the potential of corona ignition to control gasoline homogeneous charge compression ignition combustion

A Study of Combining Gasoline Engine Downsizing and Controlled Auto-Ignition Combustion

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