关键词: 柴油机；后喷策略；排气温度；排放

Abstract: Taking a high pressure common rail heavy diesel engine as the research object, a numerical model of in-cylinder combustion is established using the converge software. The accuracy of the model is verified by collecting bench test data, and the influence law of single rear injection timing and fuel injection amount on exhaust temperature and in-cylinder combustion is analyzed. Taking exhaust temperature as the target, based on the optimal result of single rear injection, the strategy of double rear injection is proposed and optimized, and the influence mechanism of double rear injection on combustion in cylinder is analyzed. The results show that the exhaust temperature increases first and then decreases with the increase of the single rear injection time when the injection amount is constant. When the single rear injection time is 25 °CA, the exhaust temperature is the highest, which increases by 146.2 ℃ compared with the condition without the single rear injection time. Based on the single rear injection, the combination of double rear injection and the interval of double rear injection are optimized. The results show that compared with single rear injection, double rear injection can effectively increase the exhaust temperature, and the emission level is similar. When the first injection volume is 50%, the second injection volume is 50%, and the interval is 10 °CA, the exhaust temperature is increased by 19.3 ℃.

Key words: Diesel engine; Rear injection strategy; Exhaust temperature; Discharge