国Ⅵ天然气发动机的EGR均匀性研究

Research on EGR Uniformity of the Natural Gas Engine for Stage Ⅵ

分析了国Ⅵ天然气发动机各缸EGR不均匀产生的原因,发现排气压力的波动会对各缸EGR流量分布产生不利影响。从改变EGR气体流动相位和流动均匀性两个方面提出了13个改进方案,建立发动机GT-SUITE一维计算模型,对改进方案进行计算分析,得到了具体的优化方案并通过台架进行试验测量,试验结果显示发动机各转速EGR率平均偏差从3.1%减小为1.2%,发动机缸内最高燃烧压力的偏差从25%减小为20%,发动机EGR均匀性大大提升。

The causes for EGR uniformity of Stage VI natural gas engine is analyzed, and found that the exhaust pressure fluctuations will be harmful to each cylinder EGR flow distribution. The 13 improvement projects about two aspects has been put forward, one is EGR gas flow phase and the other is the flow uniformity. One dimensional calculation model of engine is built up by GT-SUITE, and the solution project has been calculated by this model, the specific optimization scheme was obtained, and through bench testing measurement, experiment results show that the EGR rate deviation decreases from 3.1% to L2%, the deviation of cylinder maximum combustion pressure decreases from 25% to 20%, the engine EGR uniformity has been increased greatly.