Pre-chamber combustion (PCC) engines allow extending the lean limit of operation compared to common SI engines, thus being a candidate concept for the future clean transportation targets. To understand the fundamental mechanisms of the main chamber charge ignition in PCC engines, the effects of the composition in the pre-chamber were investigated numerically. A well-stirred reactor combustion model coupled with a methane oxidation mechanism reduced from GRI 3.0 was used. An open-cycle simulation was run with initialization at exhaust valve opening (EVO). For posterior simulations, the initial flow field was attained by mapping the field variables obtained from the full cycle simulation. The entire simulation domain (pre-chamber and main chamber) global excess air ratio (λ) was set to 1.3. As parametric variants, additional amounts of fuel were further injected into the pre-chamber to achieve a global pre-chamber λ of 0.7 and 1.0 at spark timing, thus having the pre-chamber and the main chamber with different compositions (emulating an active type pre-chamber). For the same operating conditions, the pre-chamber charge residence time after the spark ignition is mostly governed by the geometry. Therefore, by varying the air/fuel ratio (AFR) in the pre-chamber, it is possible to produce jets with various compositions and ultimately determine the impact of the pre-chamber enrichment on the main chamber response. The results show that the pre-chamber is sensitive to fuel enrichment and the results serve as a baseline guideline for subsequent studies.
Bibliographical noteKAUST Repository Item: Exported on 2021-06-17
Acknowledgements: The paper is based upon work supported by Saudi Aramco Research and Development Center FUELCOM3 program under Master Research Agreement Number 6600024505/01. FUELCOM (Fuel Combustion for Advanced Engines) is a collaborative research undertaking between Saudi Aramco and KAUST intended to address the fundamental aspects of hydrocarbon fuel combustion in engines, and develop fuel/engine design tools suitable for advanced combustion modes. The computational simulations utilized the Shaheen supercomputer at KAUST Supercomputing Laboratory. The scientific visualization was supported by the KAUST Visualization Core Laboratory. The authors thank Convergent Science Inc. for providing the CONVERGE license.
ASJC Scopus subject areas
- Safety, Risk, Reliability and Quality
- Automotive Engineering
- Industrial and Manufacturing Engineering