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Numerical study on pressure oscillation suppression of low-speed marine engine with in-cylinder direct injection of natural gas

journal contribution
posted on 08.01.2020 by Chengwei Yuan, Bo Liu, Xiaoxiao Jiang, Lei Zhou, Rui Chen, Haiqiao Wei
Based on the computational fluid dynamics (CFD) software (CONVERGE), the simulation model of a large low-speed two-stroke marine engine in which pilot diesel and natural gas are injected directly in cylinder was established. Validated by the experimental data from the literature, the model was then applied to studying the suppression effect of the Miller cycle and natural gas two-stage injection strategy on the pressure oscillation in high pressure direct injection mode. The calculation results indicated that when the exhaust valve was closed later, the overall combustion pressure was lower, both the combustion phase and the moment of severe pressure oscillation were delayed. The intensity of pressure oscillation was reduced with smaller delay of exhaust valve closing, while it was increased instead with an excessive delay. This was primarily attributed to the competitive relation between in-cylinder thermodynamic state and auto-ignition characteristics of fuel. Adjusting the pre-injection quantity of natural gas would reduce the formation of premixed combustible mixture before combustion, thus reducing the proportion of premixed combustion in the combustion phase, which could effectively suppress pressure oscillation, but could also reduce the output power and increase the fuel consumption. Compared with the pre-injection quantity, varying injection interval has less effect on the pressure oscillation, but the excessive injection interval would affect the combustion phase, resulting in considerable power loss. A reasonable injection strategy can ensure the power output while suppressing intense pressure oscillation.

Funding

Marine Low-Speed Engine Project Phase I (CDGC01-KT0308)

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

Neiranji Gongcheng/Chinese Internal Combustion Engine Engineering

Volume

40

Issue

6

Pages

56 - 63

Publisher

Shanghai Neiranji Yanjiusuo, Shanghai Internal Combustion Engine Research Institute

Version

VoR (Version of Record)

Rights holder

© Editorial Office of Chinese Internal Combustion Engine Engineering

Publisher statement

This paper was accepted for publication in the journal Neiranji Gongcheng/Chinese Internal Combustion Engine Engineering and the definitive published version is available at https://doi.org/10.13949/j.cnki.nrjgc.2019.06.009.

Publication date

2019-12-15

Copyright date

2019

ISSN

1000-0925

Language

zh

Depositor

Prof Rui Chen. Deposit date: 6 January 2020

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