Development of a New Measurement Technique for the Investigation of End-Gas Autoignition and Engine Knock

Stiebels, B.; Schreiber, M.; Sakak, A. Sadat

doi:10.4271/960827

Cited by 23 publications

(6 citation statements)

References 17 publications

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“…Generally engine knock occurs when the end gas autoignites due to a high temperature before the normal¯ame delivered by the spark plug arrives in this region. Autoignition occurs near the cylinder wall, detached from the¯ame front, where the negative temperature coecient (NTC) and low-temperature chemistry for the pre-reactions play a dominant role [10]. Hence the autoignition site can be considered as the location where the cubic splined¯ame arrival angle is the same as the knock onset angle Figure 3 shows a typical example of this method.…”

Section: Methodsmentioning

confidence: 99%

Prediction of knock onset and the autoignition site in spark-ignition engines

Lee

Pae

Min

et al. 2000

Proceedings of the Institution of Mechanical Engineers, Part D:

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A three-dimensional model of knock is developed to predict knock occurrence and the autoignition site in spark-ignition engines. A premixed turbulent combustion model, which falls within the flame area evolution category, and a flame wall quenching model are applied to simulate flame propagation. A reduced kinetic model is used to simulate autoignition in the unburned gas region. Engine experiments are performed to calibrate the reduced kinetic model and to verify the results of this modelling. A spark plug integrated pressure transducer and 11 ion probes are installed in the cylinder head to detect knock occurrences, flame arrival angles and autoignition sites. The model predictions show good agreement with the cylinder pressures, flame arrival angles, knock occurrences and autoignition site of the engine experiments with the variations in spark timing.

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Section: Methodsmentioning

confidence: 99%

Prediction of knock onset and the autoignition site in spark-ignition engines

Lee

Pae

Min

et al. 2000

Proceedings of the Institution of Mechanical Engineers, Part D:

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show abstract

“…Some new optical measurements were also being performed. Stiebels et al [220], of the Lehrstuhl für Technische Thermodynamik of RWTH Aachen University, used two Intensified Charge-Coupled Device (ICCD) cameras, 15 μs out of phase, triggered by autoignition. This allowed autoignition location and reaction spatial velocity to be studied.…”

Section: The 1990s: Chemical Kinetics Exothermic Centers and Time-fre...mentioning

confidence: 99%

Knock: A Century of Research

Corrigan¹,

Fontanesi²

2021

SAE Int. J. Engines

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Knock is one of the main limitations on increasing spark-ignition (SI) engine efficiency. This has been known for at least 100 years, and it is still the case today. Knock occurs when conditions ahead of the flame front in an SI engine result in one or more autoignition events in the end gas. The autoignition reaction rate is typically much higher than that of the flame-front propagation. This may lead to the creation of pressure waves in the combustion chamber and, hence, an undesirable noise that gives knock its name. The resulting increased mechanical and thermal loading on engine components may eventually lead to engine failure. Reducing the compression ratio lowers end-gas temperatures and pressures, reducing end-gas reactivity and, hence, mitigating knock. However, this has a detrimental effect on engine efficiency.Automotive companies must significantly reduce their fleet carbon dioxide (CO 2 ) values in the coming years to meet targets resulting from the 2015 Paris Agreement. One path towards meeting these is through partial or full electrification of the powertrain. However, the vast majority of automobiles in the near future will still feature a gasoline-fueled SI engine; hence, improvements in combustion engine efficiency remain fundamental.As knock has been a key limitation for so long, there is a huge amount of literature on the subject. A number of reviews on knock have already been published, including in recent years. These generally concentrate on current understanding and status. The present work, in contrast, aims to track the progress of research on knock from the 1920s right through to the present day. It is hoped that this can be a useful reference for new and existing researchers of the subject and give further weight to occasionally neglected historical activity, which can still provide important insights today.

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“…Much evidence of end-gas mixture auto-ignition followed by knocking combustion can be obtained from highspeed laser shadowgraphs [18], high-speed Schlieren photography [19], chemiluminescent emission [20], and laser-induced fluorescence [21]. In addition, Stiebels et al [22] and Pan and Sheppard [23] showed that multiple autoignition sites occur during knocking combustion. The combustion mode we have monitored we believe differs from knocking combustion in terms of the size, gradients, and spatial distribution of the exothermic centers in the end-gas.…”

Section: Concept Of Premier Combustionmentioning

confidence: 99%