Combustion and reaction

A Numerical Investigation on the Effects of Intake Swirl and Mixture Stratification on Combustion Characteristics in a Natural-Gas/Diesel Dual-Fuel Marine Engine

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  • 1. State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China 
    2. China Ship Power Research Institute Co., Ltd., Shanghai 200120, China

Online published: 2023-11-28

Supported by

The authors would like to acknowledge the financial supports provided by the Low-speed Marine Diesel Project (Project No. CDGC01-KT0308) and National Natural Science Foundation of China (Grant No. 91941102)

Copyright

Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2022

Abstract

Natural gas/diesel dual-fuel combustion strategy has a great potential to reduce emissions for marine engines while the high fuel consumption is the major problem. Pre-chamber system is commonly employed as the ignition system on large-bore dual-fuel marine engines especially under lean-burn condition, due to its advanced ignition stability and engine efficiency. However, the ignition and combustion mechanism in such dual-fuel pre-chamber engine is still unclear and the effects of in-cylinder swirl flow and mixture stratification on combustion require further investigation specifically. This paper numerically studied the detailed ignition mechanism and combustion process in a marine engine equipped with a pre-chamber ignition system, and revealed the flame development process in main chamber. Moreover, the effects of mixture stratification and swirl ratio on the combustion rate and further engine thermal efficiency are investigated under decoupled condition. The results mainly show that the jet flame develops along the pre-chamber orifice centerline at the initial stage and premixed combustion play an important role, while after that, heat release zone only exist at flame surface, and premixed flame propagation controls the combustion process. In addition, with higher swirl ratio the combustion rate increases significantly due to the wider ignition area. Mixture stratification degree plays a role in accelerating the combustion, either too high or too low stratification degree reduce the combustion rate, while a moderate stratification increases the combustion rate. And appropriate stratification degree by verifying the gas injection parameters can reduce fuel consumption in 0.3%.

Cite this article

YE Ying, LIU Haifeng, LI Jingrui, LIU Teng, DONG Jingjin, LIU Bo, WU Chaohui, YUE Zongyu, YAO Mingfa . A Numerical Investigation on the Effects of Intake Swirl and Mixture Stratification on Combustion Characteristics in a Natural-Gas/Diesel Dual-Fuel Marine Engine[J]. Journal of Thermal Science, 2023 , 32(1) : 414 -426 . DOI: 10.1007/s11630-022-1733-3

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