Numerical Investigation of the Free and Ducted Fuel Injections under Compression Ignition Conditions
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ArticleAuthors
Liu, Xinlei
Mohan, Balaji
Im, Hong G.

KAUST Department
Clean Combustion Research CenterComputational Reacting Flow Laboratory (CRFL)
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Date
2020-10-21Online Publication Date
2020-10-21Print Publication Date
2020-11-19Embargo End Date
2021-10-21Submitted Date
2020-08-15Permanent link to this record
http://hdl.handle.net/10754/665677
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A ducted fuel injection (DFI) strategy has been proposed as an efficient approach to reduce the soot emission in direct-injection compression ignition engines. By injecting the fuel through a small tube within the combustion chamber, a leaner air−fuel mixture is generated compared to the conventional free spray approach, which significantly inhibits the soot formation and helps to reduce the dependence of the engine on after-treatment systems. However, the soot reduction mechanism is still not fully understood. Therefore, in this work, a three-dimensional computational investigation was performed to explain the experimental results. Four different reduced chemical mechanisms were used to simulate the reacting spray A (n-dodecane) data from both the Engine Combustion Network group and literature. An improved post-processing method was also proposed to investigate the detailed combustion feature. The results revealed that the ignition processes using different mechanisms were all dominated by the same reaction CH2O + OH = HCO + H2O. Of the four reduced mechanisms, Yao mech demonstrated the best-predicted performance. Compared to the free-spray case, the DFI case generated a longer ignition delay and lift-off length and lower soot concentration owing to the significant reduction of air entrainment and longer core jet velocity from the duct exit to the lift-off length location. In addition, the DFI case had a significantly longer low-temperature heat release region but a shorter hightemperature heat release region and a smaller core between these two regions, which helps to reduce the sooting tendency.Citation
Liu, X., Mohan, B., & Im, H. G. (2020). Numerical Investigation of the Free and Ducted Fuel Injections under Compression Ignition Conditions. Energy & Fuels. doi:10.1021/acs.energyfuels.0c02757Publisher
American Chemical Society (ACS)Journal
Energy & FuelsAdditional Links
https://pubs.acs.org/doi/10.1021/acs.energyfuels.0c02757ae974a485f413a2113503eed53cd6c53
10.1021/acs.energyfuels.0c02757