Development of a chemical-kinetic database for the laminar flame speed under GDI and water injection engine conditions

Cazzoli, Giulio; Falfari, Stefania; Bianchi, Gian Marco; Forte, Claudio

doi:10.1016/j.egypro.2018.08.043

Cited by 11 publications

(13 citation statements)

References 17 publications

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“…Recently, a new correlation was proposed for keeping into account also the effect of water vapour as a diluent, based on detailed chemical simulations performed on relevant conditions that are reached during engine operation [11]. The results of the correlation, in terms of sensitivity to the diluent effect of water addition at relevant conditions, were adequately in agreement with the values of the detailed chemical simulations.…”

Section: Effect Of the Addition Of Egr And Watersupporting

confidence: 55%

“…The chemical kinetics schemes considered in the present work for the generation of the database are reported in Table 1 and they were developed for simulating the reacting features of gasoline under both high and low temperature conditions. The observations reported by Cazzoli et al [11], and an initial testing to perform a time estimate for the simulations have led to the decision of referring the present activity to results obtained with the complete POLIMI [13] scheme.…”

Section: Choice Of the Chemical Kinetics Schemementioning

confidence: 99%

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Development of a Novel Machine Learning Methodology for the Generation of a Gasoline Surrogate Laminar Flame Speed Database under Water Injection Engine Conditions

Pulga¹,

Bianchi²,

Ricci³

et al. 2019

SAE Int. J. Fuels Lubr.

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The water injection is one of the technologies assessed in the development of new internal combustion engines fulfilling new emission regulation and policy on Auxiliary Emission Strategy assessment. Besides all the positive aspects about the reduction of mixture temperature at top dead centre and exhaust gases temperature at turbine inlet, it is well known that the water vapour acts as a mixture diluter, thus diminishing the reactants burning rate. A common methodology employed for the RANS CFD simulation of the reciprocating internal combustion engines turbulent combustion relies on the flamelet approach, which requires the knowledge of the laminar flame speed and thickness. Typically, these properties are calculated by mean of correlation laws, but they do not keep into account the presence of water mass fraction. A more precise methodology for the definition of both the laminar flame speed and thickness is thus required. The interrogation of a previously computed look-up table of such properties during run time seems to be a suitable and more accurate method than using correlations. In order to generate a database with all the possible combinations of chemical and physical properties that can be reached during the simulation of internal combustion engines, including the presence of a given mass fraction of water vapour and exhaust gases, a very high number of detailed chemical kinetics simulations needs to be performed. The present work aims to introduce a new methodology for the fast generation of laminar flame characteristics look-up tables that account also for the presence of water vapour in the reacting mixture. By using this new approach, engine designers will have the possibility to generate look-up tables of laminar flame characteristics for different fuels with the same computational cost that is currently required to generate a single table.

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Section: Effect Of the Addition Of Egr And Watersupporting

confidence: 55%

Section: Choice Of the Chemical Kinetics Schemementioning

confidence: 99%

Development of a Novel Machine Learning Methodology for the Generation of a Gasoline Surrogate Laminar Flame Speed Database under Water Injection Engine Conditions

Pulga¹,

Bianchi²,

Ricci³

et al. 2019

SAE Int. J. Fuels Lubr.

Self Cite

View full text Add to dashboard Cite

show abstract

“…That is to say, the knock suppression is primarily due to the diluting effect of injected water on the charge mixture for port water injection. Another potentially important contributing factor is a reduction in flame speed due to water dilution: simulations performed by Cazzoli et al 24 showed that the laminar flame speed in a system with a stoichiometric air–fuel mixture and 6% W/F dilution is ∼25% lower than it would be without dilution.…”

Section: Resultsmentioning

confidence: 99%

Effect of relative humidity on water injection technique in downsized spark ignition engines

Khatri

Sharma

Dahlander

et al. 2020

International Journal of Engine Research

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Combustion knock is a major barrier to achieving high thermal efficiency in spark ignition engines. Water injection was recently identified as a potential way of overcoming this barrier. To evaluate its general applicability, experiments were performed on a downsized three-cylinder spark ignition engine, varying the humidity of the intake air, the water injection timing, and the engine speed. The minimum quantity of injected water required to maintain a given load (and thus level of engine performance) was determined under each set of tested conditions. The knock-suppressing effects of water injection were found to be related to changes in the fuel–air mixture’s specific heat ratio (kappa) rather than evaporative cooling, and to therefore depend on the total quantity of water in the cylinder rather than the relative humidity per se. The total quantity of water in the cylinder was also shown to be a key determinant of advancement in combustion phasing and particulate emissions under various conditions.

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“…The methodology here proposed, based on the detailed evaluation of the chemical properties of the mixture (and not only of the fuel), and therefore of its reactivity, allows properly simulating the evolution of the flame under variable quantities of water vapor, and not only as a function of pressure, temperature, mixture index, as well as EGR, whose chemical properties are different from those of the injected water, as already demonstrated [3,4].…”

Section: A Brief Overview On the Combustion Simulation Without Water ...mentioning

confidence: 92%

“…If the thermodynamic effects can be currently well captured with standard RANS CFD simulations, the effects of the water dilution on combustion duration, and indirectly also on the TiT and the engine knock limit, ask for the accurate prediction of the flame laminar speed, the flame laminar thickness and the auto-ignition time. In fact, if the main positive aspect of the water injection is its strong mixture cooling capability, besides it, it is well known that the water vapor acts as a mixture diluter, thus diminishing the reactants burning rate and changing the auto-ignition delay time [1][2][3][4]. Before entering the actual topic of scientific work, a brief analysis of the literature is necessary.…”

Section: Introductionmentioning

confidence: 99%

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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Development of a chemical-kinetic database for the laminar flame speed under GDI and water injection engine conditions

Cited by 11 publications

References 17 publications

Development of a Novel Machine Learning Methodology for the Generation of a Gasoline Surrogate Laminar Flame Speed Database under Water Injection Engine Conditions

Development of a Novel Machine Learning Methodology for the Generation of a Gasoline Surrogate Laminar Flame Speed Database under Water Injection Engine Conditions

Effect of relative humidity on water injection technique in downsized spark ignition engines

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

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