A Two-Stage Knock Model for the Development of Future SI Engine Concepts

Fandakov, Alexander; Grill, Michael; Bargende, Michael; Kulzer, André

doi:10.4271/2018-01-0855

Cited by 19 publications

(3 citation statements)

References 24 publications

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“…In [14] Vacca et al aimed to the comprehension of multiple thermodynamic effects related to water injection and to the enhancement of combustion efficiency through 3D-CFD simulations. Finally, very interesting for the present research is the work by Fandakovet al [15] where they extended the work presented in 2017 [16] with the inclusion of water: they presented a detailed reaction kinetics mechanism focused on the prediction of the low-and hightemperature mixture ignition stages (two-stage ignition) and of the temperature increase resulting from the low-temperature ignition. From an engineering point of view, the accurate (not easy) prediction of the thermodynamics and physical effects of liquid and vapor water is not sufficient since the trade-off between combustion duration, knock tendency and TiT ask for complex chemistry.…”

Section: Introductionmentioning

confidence: 91%

Advanced Combustion Modelling of High BMEP Engines under Water Injection Conditions with Chemical Correlations Generated with Detailed Kinetics and Machine Learning Algorithms

Pulga¹,

Falfari²,

Bianchi³

et al. 2020

SAE Int. J. Adv. & Curr. Prac. in Mobility

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Water injection is becoming a technology of increasing interest for SI engines development to comply with current and prospective regulations. To perform a rapid optimization of the main parameters involved by the water injection process, it is necessary to have reliable CFD methodologies capable of capturing the most important phenomena. In the present work, a methodology for the CFD simulation of combustion cycles of SI GDI turbocharged engines under water injection operation is proposed. The ECFM-3Z model adopted for combustion and knock simulations takes advantages by the adoption of correlations for the laminar flame speed, flame thickness and ignition delay times prediction obtained by a detailed chemistry calculation. The latter uses machine learning algorithms to reduce the time to generate the full database while still maintaining an even distribution along the variables of interest. The results demonstrate the applicability of the proposed methodology, capable of capturing not only the thermodynamic effects of water injection but also the chemical kinetics aspects related to the mixture water dilution whose prediction is mandatory for addressing the engine design according to different goals: complying with new emission directives and limits, turbine inlet temperature constraints, minimization of the BSFC and possibly engine power increase.

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Section: Introductionmentioning

confidence: 91%

Advanced Combustion Modelling of High BMEP Engines under Water Injection Conditions with Chemical Correlations Generated with Detailed Kinetics and Machine Learning Algorithms

Pulga¹,

Falfari²,

Bianchi³

et al. 2020

SAE Int. J. Adv. & Curr. Prac. in Mobility

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show abstract

“…To define the water-added-mixture chemical properties the complex chemistry approach is mandatory because the accurate (not easy) prediction of the thermodynamics and physical effects of liquid and vapor water is not sufficient. The authors of the present paper have derived correlations from previous works on chemical kinetics [2,9,10,11,12] to perform the RANS-CFD combustion simulations presented below.…”

Section: Literature Surveymentioning

confidence: 99%

PWI and DWI Systems in Modern GDI Engines: Optimization and Comparison Part II: Reacting Flow Analysis

Falfari

Bianchi

Pulga

et al. 2021

SAE Technical Paper Series

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The water injection is one of the recognized technologies capable of helping the future engines to work at full load conditions with stoichiometric mixture. In the present work, a methodology for the CFD simulation of reacting flow conditions using AVL Fire code v. 2020 is applied for the assessment of the water injection effect on modern GDI engines. Both Port Water Injection and Direct Water Injection have been tested for the same baseline engine configuration under reacting flow conditions. The ECFM-3Z model adopted for combustion and knock simulations have been performed by adopting correlations for laminar flame speed, flame thickness and ignition delay times prediction, to consider the modified chemical behavior of the mixture due to the added water vapor. This improved methodological approach allows considering both the fluid-dynamics aspects (in terms of turbulence level close to ignition time and average in the combustion chamber), the mixture quality and the chemical properties of the mixture (first of all the laminar flame speed) related to the water injection. The main result for the design process is the need of finding the best tradeoff between the cooling of the unburnt mixture (which reduces the knock risk), the need to preserve both the turbulence and the laminar flame speed (which is already penalized by the cooling of the charge).

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“…This approach is documented by Middleton et al 2 and is similar to that of a number of previous researchers. [13][14][15][16][17][18] Figure 5 shows an example comparing the single and two-stage knock model predictions of temperature with the detailed kinetics calculation for a prescribed pressure curve. Heat release is assumed to occur locally in a small portion of gas and does not cause a change in the overall pressure.…”

Section: Two Stage Ignition Modelmentioning

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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A Two-Stage Knock Model for the Development of Future SI Engine Concepts

Cited by 19 publications

References 24 publications

Advanced Combustion Modelling of High BMEP Engines under Water Injection Conditions with Chemical Correlations Generated with Detailed Kinetics and Machine Learning Algorithms

Advanced Combustion Modelling of High BMEP Engines under Water Injection Conditions with Chemical Correlations Generated with Detailed Kinetics and Machine Learning Algorithms

PWI and DWI Systems in Modern GDI Engines: Optimization and Comparison Part II: Reacting Flow Analysis

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

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