Gasoline Combustion Modeling of Direct and Port-Fuel Injected Engines using a Reduced Chemical Mechanism

Givler, Shawn; Raju, Mandhapati; Pomraning, Eric; Senecal, P. K.; Salman, Nameer; Reese, Ronald

doi:10.4271/2013-01-1098

Cited by 46 publications

(19 citation statements)

References 12 publications

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“…Furthermore, AMR of cells down to 0.5 mm was used inside the cylinder based on velocity and temperature subgrid scales of 1 m/s and 2.5 K, respectively. Previous RANS [39,40,41] and large eddy simulation (LES) studies [42,43] have shown that a minimum grid size of ~0.25-0.5 mm is sufficient for simulating normal SI combustion and knock. The peak cell count in the simulations reached 2 million approximately.…”

Section: Numerical Model Setupmentioning

confidence: 99%

Development of a Virtual CFR Engine Model for Knocking Combustion Analysis

Pal

Kolodziej

Choi

et al. 2018

SAE Int. J. Engines

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Knock is a major bottleneck to achieving higher thermal efficiency in spark-ignited (SI) engines. The overall tendency to knock is highly dependent on fuel anti-knock quality as well as engine operating conditions. It is, therefore, critical to gain a better understanding of fuel-engine interactions in order to develop robust knock mitigation strategies. In the present work, a numerical model based on three-dimensional (3-D) computational fluid dynamics (CFD) was developed to capture knock in a Cooperative Fuel Research (CFR) engine. For combustion modeling, a hybrid approach incorporating the G-equation model to track turbulent flame propagation, and a homogeneous reactor multizone model to predict end-gas auto-ignition ahead of the flame front and post-flame oxidation in the burned zone, was employed. In addition, a novel methodology was implemented wherein a laminar flame speed lookup table generated a priori from a chemical kinetic mechanism could be used to provide flame speed as an input to the G-equation model, instead of using conventional empirical correlations. Multi-cycle Reynolds-Averaged Navier Stokes (RANS) simulations were performed for two different spark timings (STs) corresponding to non-knocking and knocking conditions, with other operating conditions kept the same as those of a standard Research Octane Number (RON) test. Iso-octane was considered as the fuel for the numerical study. Two different reduced kinetic mechanisms were employed to describe end-gas auto-ignition chemistry and to generate the flame speed lookup table. Experimental data, including intake/exhaust boundary conditions, was provided by a spark timing sweep study conducted in an in-house CFR engine. Moreover, cylinder wall/valve/port surface temperatures and residual gas fraction (RGF) were estimated using a well-calibrated onedimensional (1-D) model. On the other hand, a novel methodology was also developed to analyze experimental data for the knocking case and identify the most representative cycle. For the non-knocking case, a good agreement was found between experiment and CFD simulation, with respect to cycle-averaged values of 10% burn point (CA10), 50% burn point (CA50) and peak pressure magnitude/location. The virtual CFR engine model was also demonstrated to be capable of predicting average knock characteristics for the knocking case, such as knock point, knock intensity and energy of resonance, with good accuracy.

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Section: Numerical Model Setupmentioning

confidence: 99%

Development of a Virtual CFR Engine Model for Knocking Combustion Analysis

Pal

Kolodziej

Choi

et al. 2018

SAE Int. J. Engines

View full text Add to dashboard Cite

show abstract

“…Nonetheless, more complex spray models are utilized to yield a more accurate description of the entire spray phenomenon. One such model is the KH-RT model which has been increasingly adapted in GDI engine simulations [129], [139], [141]. Huang and Lipatnikov [172] compared liquid penetration and SMD of gasoline and ethanol sprays predicted by various spray models which were implemented in an open source code called OpenFOAM.…”

Section: Spray Mixture Formation and Combustion Modelingmentioning

confidence: 99%

“…However, the effect of turbulent fluctuations was neglected by the combustion model. A PRF mechanism was employed by Givler et al [139] to model combustion in both direct injection and PFI gasoline engines through the multi-zone approach. The importance of selecting a mechanism which was reduced under similar operating conditions to engine cases was specifically emphasized to ensure accurate predictions.…”

Section: Spray Mixture Formation and Combustion Modelingmentioning

confidence: 99%

Developments in computational fluid dynamics modelling of gasoline direct injection engine combustion and soot emission with chemical kinetic modelling

Tan¹,

Bonatesta²,

Ng³

et al. 2016

Applied Thermal Engineering

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Designed to inject gasoline fuel directly into the combustion chamber, gasoline direct injection (GDI) combustion systems are gaining popularity among the automotive industry. This is because GDI engines offer less pumping and heat losses, enhanced fuel economy and improved transient response. Nonetheless, the technology is often associated with the emission of ultra-fine particulate matter (PM) to the atmosphere. With the increasingly stringent emission regulations, detailed understanding of PM formation within GDI engine configurations is very crucial. To complement the findings based on experimental and optical techniques, computational fluid dynamics (CFD) modeling has been widely utilized to study the in-cylinder physical and chemical events. The success of CFD simulations also requires an accurate representation of gasoline fuel kinetics. Set against the background, the present review reports on the recent developments in chemical kinetic modeling of gasoline fuels and CFD numerical studies for GDI engines emphasizing the combustion and emission stages. Regarding fuel kinetics, the use of primary reference fuel (PRF) and ternary reference fuel (TRF) mechanisms is evaluated. In addition, the current trend portrays a progression towards multi-component surrogate models to account for the complex mixture of practical fuels. It is however observed that many reaction mechanisms proposed in the literature are validated under homogeneous charge compression ignition (HCCI) engine conditions rather than GDI-related ones. CFD modeling of GDI engines typically covers the simulations of spray, mixture formation and combustion processes. Progress in combustion modeling for both homogeneous and stratified charge modes is discussed thoroughly. Still in its infancy, soot modeling studies for GDI engines are reviewed in which several soot models adapted are appraised. The majority of soot models have been previously applied in diesel combustion systems and flame configurations. Significant efforts are currently carried out to improve the model predictions of soot emission from GDI engines.

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“…To overcome the disadvantage of the G -equation-based combustion model which is dependent on the turbulent flame speed equation, some researchers have been trying to use detailed chemistry-based combustion models to simulate premixed flame propagation. Givler et al 10 presented some combustion simulation results using this method, but they did not present any theoretical description about why this method can be used. An increasing number of industry researchers are using detailed chemistry-based combustion models in their premixed combustion modeling work, but they have not justified the use of this approach.…”

Section: Introductionmentioning

confidence: 99%

Simulations of gasoline engine combustion and emissions using a chemical-kinetics-based turbulent premixed combustion modeling approach

Yang

Pomraning

Jia

2016

Proceedings of the Institution of Mechanical Engineers, Part D:

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This work presents a turbulent premixed combustion modeling approach which is based on chemical kinetics. In this approach, the smallest length scales are of the order of 0.1–1.0 mm for typical engine simulations with a Reynolds-averaged Navier–Stokes turbulence model and, after adaptive mesh refinement technology is used to consider the magnitude of the subgrid field, the Reynolds-averaged Navier–Stokes turbulent flow field can be well resolved. For solution of the flame front, an artificially thickened laminar flame concept is introduced to balance the computational accuracy and the computational cost. Around the artificially thickened laminar flame front, a special grid resolution strategy is designed, i.e. using much finer resolution in the normal direction of the flame front and typical adaptive mesh refinement resolution in the other two perpendicular directions. Then, chemical kinetics can be applied to the chemistry process which occurs in the flame front. To use this chemical-kinetics-based turbulent premixed combustion modeling approach better, a good chemical kinetics mechanism is very important. For this reason a practical primary-reference-fuel chemical kinetics mechanism is improved and validated in present work. The newly improved mechanism resolves several issues in the existing mechanisms, including unrealistically fast autoignition reactions and limited laminar flame speed validation. After reoptimization of those laminar-flame-speed-related reactions, the new mechanism can correctly compute the laminar flame speeds for a wide range of Ford spark ignition engines and for various operating conditions. Using this combustion modeling approach together with the new mechanism, simulations of the combustion and the emissions of several spark ignition engines for typical operating conditions were carried out. The simulated in-cylinder pressures, the simulated burn rates, and the simulated emissions including the brake specific carbon monoxide emissions, the nitrogen oxide emissions, and the unburned hydrocarbon emissions are compared with the experimental data, and very good agreement is found without tuning any model constants.

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Gasoline Combustion Modeling of Direct and Port-Fuel Injected Engines using a Reduced Chemical Mechanism

Cited by 46 publications

References 12 publications

Development of a Virtual CFR Engine Model for Knocking Combustion Analysis

Development of a Virtual CFR Engine Model for Knocking Combustion Analysis

Developments in computational fluid dynamics modelling of gasoline direct injection engine combustion and soot emission with chemical kinetic modelling

Simulations of gasoline engine combustion and emissions using a chemical-kinetics-based turbulent premixed combustion modeling approach

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