Correlation of autoignition phenomena in internal combustion engines and rapid compression machines

Livengood, J. C.; Wu, Pengzhi

doi:10.1016/s0082-0784(55)80047-1

Cited by 655 publications

(269 citation statements)

References 9 publications

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“…It has been found that the attainment of a value of unity by the Livengood-Wu [5] integral, I , given below, is a good indication of when autoignition will occur in an engine, I = t 0 dt t i (T , P) .…”

mentioning

confidence: 99%

Autoignitions and detonations in engines and ducts

Bradley

2012

Phil. Trans. R. Soc. A.

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The origins of autoignition at hot spots are analysed and the pressure pulses that arise from them are related to knock in gasoline engines and to developing detonations in ducts. In controlled autoignition engines, autoignition is benign with little knock. There are several modes of autoignition and the existence of an operational peninsula, within which detonations can develop at a hot spot, helps to explain the performance of various engines. Earlier studies by Urtiew and Oppenheim of the development of autoignitions and detonations ahead of a deflagration in ducts are interpreted further, using a simple one-dimensional theory of the generation of shock waves ahead of a turbulent flame. The theory is able to indicate entry into the domain of autoignition in an 'explosion in the explosion'. Importantly, it shows the influence of the turbulent burning velocity, and particularly its maximum attainable value, upon autoignition. This value is governed by localized flame extinctions for both turbulent and laminar flames. The theory cannot show any details of the transition to a detonation, but regimes of eventually stable or unstable detonations can be identified on the operational peninsula. Both regimes exhibit transverse waves, triple points and a cellular structure. In the case of unstable detonations, transverse waves are essential to the continuing propagation. For hazard assessment, more needs to be known about the survival, or otherwise, of detonations that emerge from a duct into the same mixture at atmospheric pressure.

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confidence: 99%

Autoignitions and detonations in engines and ducts

Bradley

2012

Phil. Trans. R. Soc. A.

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“…A widely employed empirical approach is to apply the conservation of delay principle proposed by Livengood and Wu [10]. According to this principle the overall ignition delay time can be found by integrating its instantaneous value during the compression and combustion stroke.…”

Section: Predictive Knock Modelingmentioning

confidence: 99%

A quasi-dimensional model for SI engines fueled with gasoline–alcohol blends: Knock modeling

Sileghem

Wallner

Verhelst

2015

Fuel

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As knock is one of the main factors limiting the efficiency of spark-ignition engines, the introduction of alcohol blends could help to mitigate knock concerns due to the elevated knock resistance of these blends. A model that can accurately predict their autoignition behavior would be of great value to engine designers. The current work aims to develop such a model for alcohol-gasoline blends. First, a mixing rule for the autoignition delay time of alcohol-gasoline blends is proposed. Subsequently, this mixing rule is used together with an autoignition delay time correlation of gasoline and an autoignition delay time correlation of methanol in a knock integral model that is implemented in a two-zone engine code. The predictive performance of the resulting model is validated through comparison against experimental measurements on a CFR engine for a range of gasoline-methanol blends.The knock limited spark advance, the knock intensity, the knock onset crank angle and the value of the knock integral at the experimental knock onset have been simulated and compared to the experimental values derived from in-cylinder pressure measurements.

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“…The former category, which constitutes the major part of the literature, includes the study of ignition delay through measurements in shock tubes and rapid compression machines [2,3], modeling by basic chemical kinetics [4,5], developing empirical correlations via engine data [6,7], and assessing the fuel effects [8,9]. The Livengood and Wu integral [10] is used to relate the fuel air mixture ignition delay behavior to the knock on set in an engine. The latter category includes the visualization of the knock phenomenon [11,12], and the numerical simulation of knock in a fuel air mixture [13].…”

Section: Introductionmentioning

confidence: 99%

The Anatomy of Knock

McKenzie¹,

Cheng²

2016

SAE Technical Paper Series

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The combustion process after auto-ignition is investigated. Depending on the non-uniformity of the end gas, auto-ignition could initiate a flame, produce pressure waves that excite the engine structure (acoustic knock), or result in detonation (normal or developing). For the "acoustic knock" mode, a knock intensity (KI) is defined as the pressure oscillation amplitude. The KI values over different cycles under a fixed operating condition are observed to have a log-normal distribution. When the operating condition is changed (over different values of , EGR, and spark timing), the mean () of log (KI/GIMEP) decreases linearly with the correlationbased ignition delay calculated using the knock-point end gas condition of the mean cycle. The standard deviation  of log(KI/GIMEP) is approximately a constant, at 0.63. The values of  and  thus allow a statistical description of knock from the deterministic calculation of the ignition delay using the mean cycle properties

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Correlation of autoignition phenomena in internal combustion engines and rapid compression machines

Cited by 655 publications

References 9 publications

Autoignitions and detonations in engines and ducts

Autoignitions and detonations in engines and ducts

A quasi-dimensional model for SI engines fueled with gasoline–alcohol blends: Knock modeling

The Anatomy of Knock

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