Abstract
The simulations of combustion and emission for an agricultural highpower diesel engine were studied under different necking sizes of combustion chamber. The results show that decreasing the necking size can result in the increase of incylinder turbulent kinetic energy and help the gas mixing, which promotes the flow within the cylinder. The cylinder pressure decreases with the decline of necking size, while the maximum pressure changes little. The temperature inside the cylinder changes slightly with the change of necking size, the necking can improve the combustion process in the cylinder, but the excessive necking size is not beneficial. For the chambers with different necking sizes, the incylinder velocity fields are almost the same at ignition timing, but the velocity field at top dead center slightly strengthens with the decrease of necking diameter. During the retarded combustion period, the combustion rate decreases rapidly in the combustion chamber with smaller necking diameter. As the necking size decreases, the maximum generation of NOx first increases and then decreases, while the tendency for the maximum generation of soot is just opposite to that of NOx . At the opening moment of exhaust valve, the NOx emission first increases and then decreases while the soot emission shows a trend of zigzag rise. The thermal efficiency first decreases and then increases with the decrease of necking diameter.
Key words
diesel engine /
combustion chamber /
combustion process /
emission
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DUAN Hao,MA Fanhua,SONG Panpan.
Effects of Combustion Chamber Necking Sizes on Combustion Process of Diesel Engine[J]. Vehicle Engine. 2018, 0(3): 43-47 https://doi.org/10.3969/j.issn.1001-2222.2018.03.007
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