A Novel Laminar Flame Speed Correlation for the Refinement of the Flame Front Description in a Phenomenological Combustion Model for Spark-Ignition Engines

Bellis, Vincenzo De; Malfi, Enrica; Teodosio, Luigi; Giannattasio, Pietro; Lenarda, Fabio Di

doi:10.4271/03-12-03-0018

Cited by 11 publications

(6 citation statements)

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“…44 Indeed, the fractal model directly describes the enhancement of the flame front surface due to its interaction with the turbulence, reproducing the observations reported in several experimental activities. 20,[36][37][38][39][40][41][42][43][44][45] As a final remark, it is worthwhile mentioning that the fractal combustion model is implemented, as well as the presented turbulence model, in the GT-Power environment under the form of user coding.…”

Section: Fractal Combustion Modelmentioning

confidence: 99%

“…The summarized fractal combustion model has been successfully applied to light-duty and high-performance gasoline engines in the past. 20,40,41 In addition, in De Bellis et al 20 it has been compared, in terms of tuning efforts and predictive accuracy, to well-known approaches, such as the eddy burn-up model. 42,43 The authors in De Bellis et al 20 found that the fractal model is characterized by a reduced constant-to-constant cross-dependency, producing lower tuning efforts with respect to the eddy burn-up model.…”

Section: Fractal Combustion Modelmentioning

confidence: 99%

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Advanced turbulence and combustion modeling for the study of a swirl-assisted natural gas spark-ignition heavy-duty engine

Riccardi

Bellis

Sforza³

et al. 2023

International Journal of Engine Research

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Increasing demands on higher performance and lower fuel consumption and emissions have led the path for internal combustion engine development; this race is nowadays directly related to CO2 emissions reduction. To drive engine development and reduce the time-to-market, the employment of numerical analysis is mandatory. This requires a continuous improvement of the simulation models toward real predictive analyses able to reduce the experimental R&D efforts. In this framework, 1D numerical codes are fundamental tools for system design, energy management optimization, and calibration. The present work is focused on the improvement of the phenomenological turbulence model, originally conceived to describe turbulence evolution in tumble-promoting engines. The turbulence model is developed with reference to a SI heavy-duty CNG engine derived from a diesel engine. In this architecture, due to the flat cylinder head, turbulence is also generated by swirl and squish flow motions, in addition to tumble motion. The presented turbulence model is validated against 3D CFD results, demonstrating to properly predict turbulence and swirl/tumble evolution under two different operating conditions, without the need for any case-dependent tuning. The developed turbulence model is coupled to a phenomenological combustion model based on the fractal geometry theory applied to the flame front surface, where the turbulence is assumed to support flame propagation through an enhancement of the flame front area with respect to the laminar counterpart. The combustion model is validated against an extensive experimental dataset, composed of 25 operating points at different engine rotational speeds and loads. The numerical/experimental comparisons of global performance parameters are satisfactory, leading to maximum errors around ±2% for the BSFC, ±2° for the main combustion events, and ±1 bar for the in-cylinder peak pressure. Burn rate profiles are very well captured by the combustion model at changing operating conditions, not requiring any case-dependent tuning. The presented results demonstrate that the turbulence/combustion models could constitute a reliable virtual test facility, contributing to supporting and driving experimental activities.

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Section: Fractal Combustion Modelmentioning

confidence: 99%

Section: Fractal Combustion Modelmentioning

confidence: 99%

Advanced turbulence and combustion modeling for the study of a swirl-assisted natural gas spark-ignition heavy-duty engine

Riccardi

Bellis

Sforza³

et al. 2023

International Journal of Engine Research

Self Cite

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“…A model for the evaluation of the pollutant emissions, namely NOx, CO, and unburned fuel, is adopted. A multi-zone approach is used to estimate the amount of NO x and CO. On one hand, the extended Zeldovich mechanism is used to evaluate the NO kinetics [31], on the other hand, a two-step reaction scheme [32] is used to describe the CO kinetics. A refined model for the evaluation of the unburned fuel is implemented, considering both the filling/emptying of the crevices volume, the flame wall quenching, and the fuel postoxidation, as explained in a previous work of the authors [30].…”

Section: Modeling Approachmentioning

confidence: 99%

Potential of hydrogen addition to natural gas or ammonia as a solution towards low- or zero-carbon fuel for the supply of a small turbocharged SI engine

2021

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Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those fuels, on one hand, allow to drastically reduce CO2 emissions, helping to comply with the increasingly stringent emission regulations, and, on the other hand, could lead to possible advantages in performances if blended with conventional fuels. In this regard, this work focuses on the 1D numerical study of an internal combustion engine supplied with different fuels: pure gasoline, and blends of methane-hydrogen and ammonia-hydrogen. The analyses are carried out with reference to a downsized turbocharged two-cylinder engine working in an operating point representative of engine operations along WLTC, namely 1800 rpm and 9.4 bar of BMEP. To evaluate the potential of methane-hydrogen and ammonia-hydrogen blends, a parametric study is performed. The varied parameters are air/fuel proportions (from 1 up to 2) and the hydrogen fraction over the total fuel. Hydrogen volume percentages up to 60% are considered both in the case of methane-hydrogen and ammonia-hydrogen blends. Model predictive capabilities are enhanced through a refined treatment of the laminar flame speed and chemistry of the end gas to improve the description of the combustion process and knock phenomenon, respectively. After the model validation under pure gasoline supply, numerical analyses allowed to estimate the benefits and drawbacks of considered alternative fuels in terms of efficiency, carbon monoxide, and pollutant emissions.

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“…Following the research discussed above, much work, for example, [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] has been focused on the turbulent combustion in SI engines, along with experimental measurements. Most of the models developed using FES were quasi-dimensional models, where the zero-dimensional thermodynamic models were applied up to the time of ignition, and two zones, burned and unburned (these two zones are often subdivided into boundary layers and isothermal cores, and a crevice zone is sometimes added as well), were utilized for the duration of the combustion process.…”

Section: Introductionmentioning

confidence: 99%

Development of a fractal engine simulation model in a multidimensional simulation for the cold start process of a gasoline direct injection engine

Hall

et al. 2023

International Journal of Engine Research

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A fractal engine simulation (FES) sub-model was integrated into three-dimensional simulations for modeling turbulent combustion for a gasoline direct injection (GDI) engine. The FES model assumes that the effects of turbulence on flame propagation are to wrinkle and stretch the flame, and fractal geometry is used to predict the surface area increase and thus the turbulent burning velocity. Different formulas for the four sequential stages of combustion in SI engines are proposed to account for the changing effects of turbulence throughout the combustion process. However, most prior studies related to the FES model were quasi-dimensional simulations, with few found in multi-dimensional studies, and none under cold start conditions or stratified charges. This paper describes how the model was implemented into multidimensional simulations in CONVERGE CFD, and what the formulas are in the four sequential stages of combustion in SI engines. The capabilities of the FES model for simulating the cold start cases, under the conditions of the dramatically changing engine speed and mixture stratification in a complex engine geometry, are presented in this study. The FES model was able to not only simulate the steady-state cases with constant engine speed, but also predict the in-cylinder pressure traces in all four cylinders for the very first firing cycle with transient engine speed, and gave good agreement with the experimental measurements under these extremely transient conditions. The uncertain maximum fractal dimension was chosen as 2.37 in this research, and a simple linear correlation with engine speed was used to obtain the coefficient used in calculating the kernel formation time which controls the so-called combustion or ignition delay.

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A Novel Laminar Flame Speed Correlation for the Refinement of the Flame Front Description in a Phenomenological Combustion Model for Spark-Ignition Engines

Cited by 11 publications

References 0 publications

Advanced turbulence and combustion modeling for the study of a swirl-assisted natural gas spark-ignition heavy-duty engine

Advanced turbulence and combustion modeling for the study of a swirl-assisted natural gas spark-ignition heavy-duty engine

Potential of hydrogen addition to natural gas or ammonia as a solution towards low- or zero-carbon fuel for the supply of a small turbocharged SI engine

Development of a fractal engine simulation model in a multidimensional simulation for the cold start process of a gasoline direct injection engine

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