自然吸气式CNG发动机主充模型的研究

Research on Main Charging Model of Naturally Aspirated CNG Engine

为了准确预测自然吸气式压缩天然气(Compressed Natural Gas,CNG)发动机的空气流量,基于汽油机进气系统平均值模型,构建了CNG发动机的主充模型。根据CNG发动机进气系统的实际工作环境,引入了温度修正系数、体积修正系数、燃气量修正系数等参数,计算了不同工况下CNG发动机的空气流量。通过CNG发动机台架试验,测量了不同转速、不同进气歧管压力下的空气流量;对比分析了空气流量的计算值和试验值的方法,评估了模型的预测性能。结果表明,所建立的主充模型能较好的预测不同转速下空气流量随CNG发动机进气歧管压力的变化规律,空气流量的预测值与实验值的最大误差小于3%,模型具有较高的预测精度。

In order to accurately predict the air flow of a naturally aspirated Compressed Natural Gas(CNG)engine,a main charging model for CNG engines was constructed based on the average model of the gasoline engine intake system.According to the actual working environment of the CNG engine air intake system,parameters such as temperature correction coefficient,volume correction coefficient,and gas volume correction coefficient were introduced to calculate the air flow rate of CNG engine under different operating conditions.Through the CNG engine bench test,the air flow at different speeds and different intake manifold pressures were measured;the calculated and tested values of the air flow were compared and analyzed,and the predictive performance of the model was evaluated.The results show that the established main charging model can better predict the change of air flow with the intake manifold pressure of CNG engines at different speeds.The maximum error between the predicted value of the air flow and the experimental value is less than 3%,and the model has a higher prediction accuracy.