【摘要】 在油滴蒸发准维燃烧模型的基础上,考虑燃油喷雾、蒸发、空气卷吸及传热的影响,结合生成NOx的化学动力学机理,建立直喷式柴油机的燃烧及NOx计算模型 实测直喷式柴油机多种转速负荷特性的NOx排放,得出柴油机运行范围内的NOx排放特性,并与模拟计算结果进行对比分析,两者变化较吻合 柴油机在低速大负荷时由于最高燃烧压力较大,温度较高,燃气在高温下停留时间较长,NOx排放浓度较大 供油提前角增加时,着火始点提前,最高燃烧压力及温度增加,NOx排放浓度也增加更多还原

【Abstract】 A combustion and NO_x formation model for direct injection(DI) diesel engine is established. The model combines the quasi-dimensional spray combustion model based on Hiroyuki Hiroyasu’s model and the detailed chemical kinetics of NO_x formation. The fuel spray, evaporation, air movement and heat transfer are considered. The NO_x emissions at various speeds and loads are measured. The simulated and experimental characteristics of NO_x emission within the opera-)ting conditions of the DI diesel engine are coincident. The NO_x emission concentration is higher at low speed and large load due to the higher combustion pressure, temperature and the longer stay of combustion mixture at high temperature. The NO_x emission concentration increases when the fuel delivery advance angle increases due to the earlier ignition and higher combustion pressure and temperature.更多还原