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本文系统地介绍了一个能预测静止燃烧室柴油机多种工况下的燃烧过程及性能参数的燃烧数学模型。经过分析直喷式柴油机在低负荷工况下喷射过程的特点后,文章提出了脉冲射流混合、单油滴等温蒸发模型。模型采用了脉冲喷射方法,分别计算不同时刻喷入气缸的燃油小区的空气卷入及燃油蒸发过程,再用折积的方法计算总空气卷入率及总蒸发率。此外,在模型中还模拟计算了着火迟延期、化学动力学及缸内温度的均匀化过程。理论计算与实验结果的一致性令人十分满意。模型不仅能很好地用于高负荷工况,也可以适用于低负荷工况及改变喷油定时的情况,且能较好地反映发动机及喷射系统结构参数对发动机性能的影响。此外,模型还可对柴油机燃烧及排气污染的机理进行分析研究。此模型的 FORTRAN 程序(HCCM2.2)可以在微型计算机上运行,1℃A 步长时机时约为2～3min(IBM—PC 机)。
This paper systematically introduces a combustion mathematical model that can predict the combustion process and performance parameters under various operating conditions of stationary combustion chamber diesel engine. After analyzing the characteristics of injection process of direct injection diesel engine under low load condition, the article puts forward the pulse jet mixing and single oil droplet isothermal evaporation model. The model uses the pulse injection method to calculate the air entrainment and fuel evaporation process of the fuel cells injected into the cylinder at different times respectively and then calculates the total air entrainment rate and the total evaporation rate by the method of entrapment. In addition, the model also simulates the ignition delay, chemical kinetics and cylinder temperature homogenization process. The consistency of theoretical calculation and experimental results is very satisfactory. The model can not only be used in high load conditions, but also in low load conditions and fuel injection timing, and can better reflect the influence of engine and injection system structural parameters on engine performance. In addition, the model can also analyze the mechanism of diesel combustion and exhaust pollution. The FORTRAN program (HCCM2.2) of this model can be run on a microcomputer with an approximate 1-minute A-step at about 2 to 3 minutes (IBM-PC).