Characteristic Time Analysis of SI Knock with Retarded Combustion Phasing in Boosted Engines

Lavoie, George A.; Middleton, Richard H.; Martz, Jason; Makkapati, Satheesh; Curtis, Eric W.

doi:10.4271/2017-01-0667

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…In this case, the unburned mass fraction and the volume terms are similar to the IFP model but the rpm term has been replaced by an exponential term suggesting an Arrhenius reaction rate at the time of auto-ignition based on the unburned temperature, T U . As noted in our earlier study of characteristic times for knock, 34 when knock occurs, the ignition delay at the time of knock tends to scale inversely with rpm, that is, with the time available, so this term is partially equivalent to the rpm term in the IFP model. M GT is a calibration multiplier.…”

Section: Knock Intensity Modelsmentioning

confidence: 99%

Knock and knock intensity models for boosted SI conditions with gasoline-ethanol blends

Lavoie

Middleton

Martz

et al. 2021

International Journal of Engine Research

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In this work, a previously developed, two-stage table-lookup kinetic method for surrogate Toluene Reference Fuels (TRF) was extended to gasoline-ethanol blends and exercised in a GT-POWER model of knock in several engines. Experimentally, the knock limit is normally determined by the magnitude of pressure oscillations, known as the knock intensity (KI), rather than the crank angle of initial pressure oscillations or the crank angle of auto-ignition, which is difficult to identify. A number of empirical expressions of knock intensity have been developed for modeling purposes which relate the knock intensity to the crank angle and conditions at auto-ignition, and are available in the literature. These models were implemented into a GT-POWER model and tested against experimental knock-limited data for gasoline and gasoline-ethanol blends. The KI models are phenomenological in nature and are based on varying conceptual views of the knock event. With calibration all methods gave satisfactory results at mid-speed conditions when compared with the experimental data. Some deviations were seen at low and high speeds. Low speeds are potentially important because both RON and MON testing occurs under such conditions. Implications of the results and their relationship to recent knock experimental work are discussed and suggestions offered for improved knock models.

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Section: Knock Intensity Modelsmentioning

confidence: 99%

Knock and knock intensity models for boosted SI conditions with gasoline-ethanol blends

Lavoie

Middleton

Martz

et al. 2021

International Journal of Engine Research

Self Cite

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show abstract

“…As the end gas temperature increases over 750K, the change in ignition delay decreases and is highly relevant in the knock performance of boosted and spark retard operation. 15,17,[24][25][26] With increase in boost pressure over 1.5 bar-a, LTHR becomes a limitation in SI gasoline engines. 27 Unlike gasoline, ethanol and methanol do not exhibit an NTC region and has a much longer ignition delay time in the low and medium temperature regimes, thereby allowing increased boosting compared gasoline.…”

Section: Introductionmentioning

confidence: 99%

Alcohol lean burn in heavy duty engines: Achieving 25 bar IMEP with high efficiency in spark ignited operation

Mahendar

Larsson

Erlandsson

2020

International Journal of Engine Research

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Knock is the most crucial limitation in attaining the peak load required at high efficiency in heavy duty (HD) spark ignition (SI) engines. Renewable fuels such as ethanol and methanol have high resistance to autoignition and can help overcome this limitation. To reduce knock and improve efficiency further, dilution can be used to add specific heat capacity and reduce combustion temperature. This work studied diluted combustion and knock characteristics of gasoline, ethanol, and methanol on a HD SI single cylinder engine for a wide load range. Ethanol and methanol displayed excellent knock resistance which allowed a peak gross IMEP of 25.1 and 26.8 bar respectively, compared to gasoline which only reached 8.3 bar at [Formula: see text]1.4 with a compression ratio of 13. Over 18% increase in gross IMEP was possible for gasoline and ethanol when increasing air excess ratio from 1 to 1.4. Methanol achieved the target gross IMEP at [Formula: see text]1 and required no spark retard at [Formula: see text]1.6. A peak indicated efficiency above 48% was recorded for ethanol and methanol at [Formula: see text]1.6 and gross IMEP of approximately 21 bar. At part loads, stable operation was possible until [Formula: see text]1.8 for all fuels. Increase in intake temperature showed a marginal improvement in stability but no increase in lean limit. The concept shows promise as diluted combustion of ethanol and methanol reduced knock and achieved diesel baseline load. With optimization, there is potential to improve efficiency further and possible cost savings compared to commercial diesel engines.

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Challenges for Spark Ignition Engines in Heavy Duty Application: a Review

Mahendar

Erlandsson

Adlercreutz³

2018

SAE Technical Paper Series

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Characteristic Time Analysis of SI Knock with Retarded Combustion Phasing in Boosted Engines

Cited by 6 publications

References 15 publications

Knock and knock intensity models for boosted SI conditions with gasoline-ethanol blends

Knock and knock intensity models for boosted SI conditions with gasoline-ethanol blends

Alcohol lean burn in heavy duty engines: Achieving 25 bar IMEP with high efficiency in spark ignited operation

Challenges for Spark Ignition Engines in Heavy Duty Application: a Review

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