The 3D numerical simulation of combustion process for a high pressure direct injection natural gas engine was conducted based on the chemical kinetics mechanism of nheptane and methane and the trends of NOx, CO and soot emissions were predicted. The results indicated that the total depth decrease and the throat diameter increase of reentrant combustion chamber could lead to an enhanced diffusion flame propagation of natural gas and higher indicated thermal efficiency. The flow motion of regular combustion chamber with the same depth had little effect on diffusion flame propagation of natural gas and the shallow bowl and large throat of combustion chamber was not helpful to flame propagation in the premixed combustion stage so that the indicated thermal efficiency decreased. The reentrant combustion chamber with shallow and narrow characteristics would lead to the higher NOx emission, but achieved the lower CO and soot emissions. Accordingly, the reentrant combustion chamber with reasonable geometry parameters was beneficial to improve the thermal efficiency and emission.
LI Menghan
,
TIAN Hongjian
,
ZHANG Qiang
,
LIU Xiaori
. Numerical Study on Combustion Process for High Pressure Direct Injection Natural Gas Engine[J]. Vehicle Engine, 2019
, 0(1)
: 7
-15
.
DOI: 10.3969/j.issn.1001-2222.2019.01.002
