Abstract
The phenomenon of in-cylinder pressure high-frequency oscillations has an important impact on the combustion stability, operating reliability and emission levels of diesel engine. In order to explore the influence of fuel injection quantity on the in-cylinder pressure oscillation and emission characteristics at low speed, a single cylinder diesel engine test platform was used to obtain the combustion pressure, heat release rate, IMEP, and NOx and Soot emissions under the conditions of injection pressure of 40 MPa and injection pulse width of 3 500~6 000 μs at low speed (800 r/min). The test results show that the peak pressure in the cylinder gradually increases with the increase of fuel injection quantity under low speed conditions. The amplitude of pressure high-frequency oscillations exhibits a non-monotonic variation pattern of increase first and then decrease. When the injection pulse width is 5 000 μs, the amplitude of in-cylinder pressure high-frequency oscillation reaches the maximum value of 0.84 MPa. The variations of heat release indicators such as pressure rise rate, heat release rate, ignition delay and IMEP are highly consistent with those of cylinder pressure oscillation. The maximum value of in-cylinder pressure oscillation roughly corresponds to the optimal value of the above-mentioned indicators. Proper intensity of cylinder pressure oscillation is beneficial to improving combustion efficiency. In addition, the Soot emissions exhibit a two-stage nonlinear increase pattern with the increase of fuel injection quantity, and the NOx emissions exhibit a non-monotonic change pattern of increase first and then decrease. These changes are caused by the change of in-cylinder equivalent ratio concentration led by increased fuel injection and in-cylinder pressure oscillation.
Key words
diesel engine /
fuel injection quantity /
pressure oscillation /
combustion process /
emission
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LI Yikai，XUE Zefeng，WANG Dongfang，SHI Zhongjie，XIE Yong，LI Yaozong.
Influence of Fuel Injection Quantity on InCylinder Pressure Oscillation and Emission Characteristics of Diesel Engine at Low Speed[J]. Vehicle Engine. 2023, 0(6): 1-9 https://doi.org/10.3969/j.issn.1001-2222.2023.06.001
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