A control-oriented model of turbulent jet ignition combustion in a rapid compression machine

Song, Ruitao; Gentz, Gerald; Zhu, Guoming; Toulson, Elisa; Schock, H.

doi:10.1177/0954407016670303

Cited by 18 publications

(17 citation statements)

References 18 publications

(28 reference statements)

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“…Furthermore, the mixture exiting the orifice can be a mixture of both fresh reactants and products. These features can be included in a zonal model [13], however a proper calibration using experimental measurements and CFD simulations is required. Although a more detailed model is able to improve the quantitative predictions, the simplified description of the process provides useful qualitative trends.…”

Section: Thermodynamic Approachmentioning

confidence: 99%

Fundamental Aspects of Jet Ignition for Natural Gas Engines

Mastorakos

Allison

Giusti

et al. 2017

SAE Int. J. Engines

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Large-bore natural gas engines may use pre-chamber ignition. Despite extensive research in engine environments, the exact nature of the jet, as it exits the pre-chamber orifice, is not thoroughly understood and this leads to uncertainty in the design of such systems. In this work, a specially-designed rig comprising a quartz pre-chamber fit with an orifice and a turbulent flowing mixture outside the pre-chamber was used to study the pre-chamber flame, the jet, and the subsequent premixed flame initiation mechanism by OH* and CH* chemiluminescence. Ethylene and methane were used. The experimental results are supplemented by LES and 0D modelling, providing insights into the mass flow rate evolution at the orifice and into the nature of the fluid there. Both LES and experiment suggest that for large orifice diameters, the flow that exits the orifice is composed of a column of hot products surrounded by an annulus of unburnt pre-chamber fluid. At the interface between these layers, a cylindrical reaction zone is formed that propagates in the main chamber in the axial direction assisted by convection in the jet, but with limited propagation in the cross-stream direction. For small orifice diameters, this cylinder is too thin, and the stretch rates are too high, for a vigorous reaction zone to escape the pre-chamber, making the subsequent ignition more difficult. The methane jet flame is much weaker than the one from ethylene, consistent with the lower flame speed of methane that suggests curvature-induced quenching at the nozzle and by turbulent stretch further downstream. The velocity of the jet is too high for the ambient turbulence to influence the jet, although the latter will affect the probability of initiating the main premixed flame. The experimental and modelling results are consistent with ongoing Direct Numerical Simulations at ETH Zurich.

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Section: Thermodynamic Approachmentioning

confidence: 99%

Fundamental Aspects of Jet Ignition for Natural Gas Engines

Mastorakos

Allison

Giusti

et al. 2017

SAE Int. J. Engines

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“…Subplots for 4000 rpm and 4500 rpm represent loads of 60 NÁm and 120 NÁm with the low and high peak pressures, respectively. [4] should be done to study the complexity of the problem. However, single-zone analysis should be able to produce reliable simplified results since the prechamber volume in a DM-TJI engine is as small as 3% of volume at top dead center [3].…”

Section: Heat Release Analysis Of a Dual Mode Turbulent Jet Ignitionmentioning

confidence: 99%

“…The dual mode, turbulent jet ignition (DM-TJI) is an engine combustion technology wherein an auxiliary air supply apart from an auxiliary fuel injection, as seen in TJI systems, is provided into the prechamber [3,4]. Upon spark ignition in the prechamber, highly energetic chemically active turbulent jets enter the main chamber through a multi-orifice nozzle and ignite the lean air/fuel mixture inside the main chamber.…”

Section: Introductionmentioning

confidence: 99%

Combustion Model for a Homogeneous Turbocharged Gasoline Direct-Injection Engine

Tolou

Vedula

Schock

et al. 2017

Volume 2: Emissions Control Systems; Instrumentation, Controls, and Hybrids; Numerical Simulation; Engine Design and Mechanical

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Homogeneous charge is a preferred operation mode of gasoline direct-injection (GDI) engines. However, a limited amount of work exists in the literature for combustion models of this mode of engine operation. Current work describes a model developed and used to study combustion in a GDI engine having early intake fuel injection. The model was validated using experimental data obtained from a 1.6L Ford EcoBoost® four-cylinder engine, tested at the U.S. EPA. The start of combustion was determined from filtered cycle-averaged cylinder pressure measurements, based on the local maximum of third derivative with respect to crank angle. The subsequent heat release, meanwhile, was approximated using a double-Wiebe function, to account for the rapid initial pre-mixed combustion (stage 1) followed by a gradual diffusion-like state of combustion (stage 2) as observed in this GDI engine. A non-linear least-squares optimization was used to determine the tuning variables of Wiebe correlations, resulting in a semi-predictive combustion model. The effectiveness of the semi-predictive combustion model was tested by comparing the experimental in-cylinder pressures with results obtained from a model built using a one-dimensional engine simulation tool, GT-POWER (Gamma Technologies). Model comparisons were made for loads of 60, 120, and 180 N-m at speeds ranging from 1500 to 4500 rpm, in 500 rpm increments. The root-mean-square errors between predicted cylinder pressures and the experimental data were within 2.5% of in-cylinder peak pressure during combustion. The semi-predictive combustion model, verified using the GT-POWER simulation, was further studied to develop a predictive combustion model. The performance of the predictive combustion model was examined by regenerating the experimental cumulative heat release. The heat release analysis developed for the GDI engine was further applied to a dual mode, turbulent jet ignition (DM-TJI) engine. DM-TJI is an advanced combustion technology with a promising potential to extend the thermal efficiency of spark ignition engines with minimal engine-out emissions. The DM-TJI engine was observed to offer a faster burn rate and lower in-cylinder heat transfer when compared to the GDI engine under the same loads and speeds.

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“…The dual-mode, turbulent jet ignition (DM-TJI) system is an engine combustion technology wherein an auxiliary air supply apart from an auxiliary fuel injection is provided into the pre-chamber. 1–3 The supplementary air supply and its method of delivery to the pre-chamber of a DM-TJI system are the main modification to the technology’s predecessor, turbulent jet ignition (TJI) system. 4–9…”

Section: Introductionmentioning

confidence: 99%

Experiments and modeling of a dual-mode, turbulent jet ignition engine

Tolou

Schock

2019

International Journal of Engine Research

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The dual-mode, turbulent jet ignition system is a promising combustion technology to achieve high diesel-like thermal efficiency at medium to high loads and potentially exceed diesel efficiency at low-load operating conditions. The dual-mode, turbulent jet ignition systems to date proved a high level of improvement in thermal efficiency compared to conventional internal combustion engines. However, some questions were still unanswered. The most frequent question regarded power requirements for delivering air to the pre-chamber of a dual-mode, turbulent jet ignition system. In addition, there was no study available to predict the expected efficiency of a dual-mode, turbulent jet ignition engine in a multi-cylinder configuration. This study, for the first time, predicts the ancillary work requirement to operate the dual-mode, turbulent jet ignition system. It also presents a novel, reduced order, and physics-based model of the dual-mode, turbulent jet ignition engine with a pre-chamber valve assembly. The developed model was calibrated based on experimental data from the Prototype II dual-mode, turbulent jet ignition engine. The simulation results were in good agreement with the experimental data. The validity of the model was observed based on the standard metric of the coefficient of determination as well as comparison plots for in-cylinder pressures. Numerical predictions were compared to experiments for three metrics of main chamber combustion: gross indicated mean effective pressure, main chamber peak pressure, and main chamber phasing for the peak pressure. Predictions were within 5% of experimental data, with one exception of 6%. In addition, the absolute root mean square errors of in-cylinder pressures for both pre- and main-combustion chambers were below 0.35. The calibrated model was further studied to introduce a predictive and generalized model for dual-mode, turbulent jet ignition engines. Such a model can project engine behavior in a multi-cylinder configuration over the entire engine fuel map.

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A control-oriented model of turbulent jet ignition combustion in a rapid compression machine

Cited by 18 publications

References 18 publications

Fundamental Aspects of Jet Ignition for Natural Gas Engines

Fundamental Aspects of Jet Ignition for Natural Gas Engines

Combustion Model for a Homogeneous Turbocharged Gasoline Direct-Injection Engine

Experiments and modeling of a dual-mode, turbulent jet ignition engine

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