对于采用废气分层技术的发动机,经常需要进行整机性能和工作过程优化。在优化过程中,一般采用经验的燃烧热力学模型。为了能够利用现有的计算软件或程序,并获得较高的模拟计算精度,对新型的燃烧系统,需要进一步发展更合适的计算模型。针对所研究的废气滚流分层技术,提出了一个燃烧比速率的零维单区双曲线模型。该模型采用了单区模型的思想,且采用两条曲线分别描述新鲜气层和废气层的燃烧速率。试验结果表明,该模型对废气分层技术的燃烧特点,能够做出有效的预测,且没有增加计算工作量。
Stratified charge technique has a promising in realizing gasoline clean combustion, lower fuel consumption and higher power output. It is necessary to optimize the engine overall performances for tumble generating stratified-EGR technique. The available simulation programs have been widely used in engine optimization study. However, the combustion in stratified charge engine is different from that in homogeneous charge engine, thus some modifications should be made in using these programs. This paper presents a simple method for predicting the pressure of SI engine with tumble generating stratified-EGR, using a simplified single zone combustion model, in which two exponential functions are introduced to calculate the rate of fuel burned in different charge zones. The validity of the model was made by comparing the model results with those of engine testing. Good agreement between the measured cylinder pressure and calculated cylinder pressure is obtained.