Engine Knock -An End-Gas Explosion

Haskell, W. W.; Bame, J. L.

doi:10.4271/650506

Cited by 18 publications

(5 citation statements)

References 28 publications

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“…This could then be accessed by a computer and data plots from many cycles produced. Haskell [120], at Shell's Wood River Research Laboratory, measured knocking wavefront transit times, using two piezoelectric sensors and an oscilloscope triggered by an ion-current sensor. He observed only sonic velocities, and hence no detonation waves (which have supersonic propagation velocities) were detected.…”

Section: Road Octane Number a Ron B Mon Cmentioning

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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Section: Road Octane Number a Ron B Mon Cmentioning

confidence: 99%

Knock: A Century of Research

Corrigan¹,

Fontanesi²

2021

SAE Int. J. Engines

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“…Additionally, one of the primary motivations for the implementation of dualfuel combustion in SI engines has also been for the development of better engine knock control techniques. Engine knock, the inadvertent auto-ignition of the fuel in localized high pressure and temperature regions inside the cylinder [72,73], can result in significant engine damage and marks one of the main obstacles in SI engines. The conventional approach to avoiding knock in spark-ignited (SI) engines consists of delaying the combustion phasing by retarding the spark timing [74].…”

Section: Dual-fuel Spark-ignited Enginesmentioning

confidence: 99%

“…Engines with dual-fuel capabilities can use a low RON fuel and a high RON fuel simultaneously to optimize the fuel mixture's knock resistance by controlling the proportion of each injected fuel. Many studies have explored the implementation of a dual-fuel strategy to suppress knock [2][3][4][5][72][73][74][75].…”

Section: Dual-fuel Spark-ignited Enginesmentioning

confidence: 99%

Dual-Fuel Combustion

Kassa¹,

Hall²

2019

The Future of Internal Combustion Engines

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The implementation of a dual-fuel combustion strategy has recently been explored as a means to improve the thermal efficiencies of internal combustion engines while simultaneously reducing their emissions. Dual-fuel combustion is utilized in compression ignition (CI) engines to promote the use of more readily available gaseous fuels or more efficient, advanced combustion modes. Implementing dual-fuel injection technologies on these engines also allows (1) for improved control of the combustion timing by varying the proportion of two simultaneously injected fuels, and (2) for the use of more advanced combustion modes at high load since the two injected fuels ignite in succession reducing the high peak pressures that generally act as a limiting factor. In spark-ignited (SI) engines, the implementation of a dual-fuel combustion strategy serves as an alternative approach to avoid engine knock. The dual-fuel SI engine relies on the simultaneous injection of a low knock resistance and high knock resistance fuel to dynamically adjust the fuel mixture's resistance to knock as required. The dual-fuel SI engine thereby successfully suppresses knock without compromising the engine efficiency. This chapter discusses the technological advancements associated to dual-fuel combustion and the respective gains in fuel efficiency and emissions reductions that have been achieved.

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“…Engine knock is the inadvertent auto-ignition of fuel in localized high pressure and temperature regions inside the cylinder [1,2]. Engine knock can result in significant engine damage and marks one of the main obstacles preventing spark-ignited (SI) engines from attaining higher fuel efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Knock Intensity Distribution and a Stochastic Control Framework for Knock Control

Kassa

Hall

Pamminger

et al. 2019

Journal of Dynamic Systems, Measurement, and Control

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One of the main factors limiting the efficiency of spark-ignited engines is the occurrence of engine knock. In high temperature and high pressure in-cylinder conditions, the fuelair mixture auto-ignites creating pressure shock waves in the cylinder. Knock can significantly damage the engine and hinder its performance; as such, conservative knock control strategies are generally implemented that avoid such operating conditions at the cost of lower thermal efficiencies. Significant improvements in the performance of conventional knock controllers are possible if the properties of the knock process are better characterized and exploited in knock controller designs. One of the methods undertaken to better characterize knocking instances is to employ a probabilistic approach, in which the likelihood of knock is derived from the statistical distribution of knock intensity.

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Engine Knock -An End-Gas Explosion

Cited by 18 publications

References 28 publications

Knock: A Century of Research

Knock: A Century of Research

Dual-Fuel Combustion

Knock Intensity Distribution and a Stochastic Control Framework for Knock Control

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