Effect of VVL Coupling Injection Strategy on Mixture Formation of GDI Engine

GONG Zhen; QIAN Yejian; LUO Lin; QI Jingjing; ZHAO Peng; SHAO Xiaowei

doi:10.3969/j.issn.10012222.2017.02.005

Vehicle Engine ›› 2017, Vol. 0 ›› Issue (2) : 27-34. DOI: 10.3969/j.issn.10012222.2017.02.005

Effect of VVL Coupling Injection Strategy on Mixture Formation of GDI Engine

GONG Zhen, QIAN Yejian, LUO Lin, QI Jingjing, ZHAO Peng, SHAO Xiaowei#br# #br#

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Abstract

A simulation computation model of GDI engine was established by using Ansys Fluent 3D Simulation software to calculate the
effect of variable valve lift coupled with different injection strategies on incylinder
flow and mixture formation. The results showed that the low valve lift
condition improved incylinder turbulent motion
intensity, fuel evaporation, wall wetting and mixture quality at ignition
timing more than the high valve lift condition did. In the low valve lift
condition, two stage injection shortened mixing time of fuel and air and the
seriouslydelayed second injection would worsen mixture
quality and wall wetting. When the second injection delayed, wall wetting and
mixture quality deteriorated gradually. In the high valve lift condition, two
stage injection improved mixture homogeneity. When the second injection
delayed, the mass of fuel evaporation increased, wall wetting became serious
and so mixture quality improved. For the low valve lift condition, the two
stage injection strategy in which the second injection timing was 470°CA and the injection mass ratio of two injection was 7∶3 had a good effect on fuel evaporation, wall wetting and incylinder mixture quality at ignition timing, and was the most
reasonable solution.

Key words

gasoline direct injection engine / variable valve lift;
injection strategy / fuel evaporation / wall wetting / mixture formation

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GONG Zhen, QIAN Yejian, LUO Lin, QI Jingjing, ZHAO Peng, SHAO Xiaowei. Effect of VVL Coupling Injection Strategy on Mixture Formation of GDI Engine[J]. Vehicle Engine. 2017, 0(2): 27-34 https://doi.org/10.3969/j.issn.10012222.2017.02.005