In-Cylinder Charge Motion Development for Gasoline Engine

To meet the future requirements of fuel economy and exhaust emissions, high-efficiency gasoline engines tend to employ diluted combustion concepts along with intensified charge motion and stratified mixtures. Securing the ignition of such mixtures over the full engine operation range is challenging, because of the lowered mixture reactivity and increased discrepancy of stoichiometry. In recent years, increasing research efforts have been spending on innovations of ignition technologies to tackle the challenges. In this paper, the directions of ignition improvement are highlighted based on the fundamental understanding of the ignition mechanisms. The working principles of the primary types of advanced ignition systems are introduced; and relevant engine and combustion vessel test results are reviewed. The ignition systems are categorized as: (1) high-energy spark ignition, (2) pulsed nanosecond discharge ignition, (3) radio-frequency plasma ignition, (4) laser-induced plasma ignition, and (5) pre-chamber ignition. The advanced ignition systems are commented, regarding the ignition effectiveness and the implementation challenges, according to the literatures and the extensive empirical work at the authors’ laboratory.

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High Performance Computing and Analysis-Led Development of High Efficiency Dilute Opposed Piston Gasoline Engine

Volume 1: Large Bore Engines; Fuels; Advanced Combustion ◽

10.1115/icef2017-3616 ◽

2017 ◽

Cited By ~ 1

Author(s):

Siddhartha Banerjee ◽

Clayton Naber ◽

Michael Willcox ◽

Charles E. A. Finney ◽

K. Dean Edwards

Keyword(s):

High Performance Computing ◽

High Performance ◽

Large Scale ◽

High Efficiency ◽

Gasoline Engine ◽

National Laboratory ◽

Charge Motion ◽

Oak Ridge ◽

Light Load ◽

Performance Computing

Pinnacle is developing multi-cylinder 1.2 L gasoline engine for automotive applications using high performance computing (HPC) and analysis methods. Pinnacle and Oak Ridge National Laboratory executed large-scale multi-dimensional combustion analyses at the Oak Ridge Leadership Computing Facility to thoroughly explore the design space. These HPC-led investigations show high fuel efficiency (∼46% gross indicated efficiency) may be achieved by operating with extremely high charge dilution levels of exhaust gas recirculation (EGR) at a light load key drive cycle condition (2000 RPM, 3 bar BMEP), while simultaneously attaining high levels of fuel conversion efficiency and low NOx emissions. In this extremely dilute environment, the flame propagation event is supported by turbulence and bulk in-cylinder charge motion brought about by modulation of inlet port flow. This arrangement produces a load and speed adjustable amalgamation of swirl and counter-rotating tumble which provides the turbulence required to support stable low-temperature combustion (LTC). At higher load conditions, the engine may operate at more traditional combustion modes to generate competitive power. In this paper, the numerical results from these HPC simulations are presented. Further HPC simulations and test validations are underway and will be reported in future publications.

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Spray propagation and mixture formation in an air guided direct injection gasoline engine

International Journal of Engine Research ◽

10.1243/1468087001545119 ◽

2000 ◽

Vol 1 (2) ◽

pp. 163-170 ◽

Cited By ~ 4

Author(s):

P Adomeit ◽

O Lang ◽

S Pischinger

Keyword(s):

Gasoline Engine ◽

Cfd Simulation ◽

Direct Injection ◽

Operation Mode ◽

Cone Angle ◽

Injection Pressure ◽

Gasoline Direct Injection ◽

Orifice Diameter ◽

Charge Motion ◽

Mixture Formation

Numerical analysis is used to gain information on the spray propagation and mixture formation in tumble guided gasoline direct injection (DI) engines. In order to achieve reliable predictions an atomization model for high-pressure swirl injectors is described and verified by comparison to experimental data. The approach is capable of adequately predicting the most important effects, such as nozzle orifice diameter, cone angle or injection pressure on spray development. Furthermore, it is found that the pre-jet generated at the beginning of the injection strongly affects the overall spray development. The temporal development of the pre-jet is described empirically. The in-cylinder computational fluid dynamics (CFD) analysis reveals that the tumble charge motion strongly affects spray propagation and mixture formation in the stratified operation mode, as it transports the fuel vapour cloud towards the spark plug. The CFD simulation improves understanding of the interaction between the flow field, spray propagation and evaporation and enables guidance of the optimization of the flow control and of the injection parameters for tumble guided gasoline DI engines.

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