柴油-天然气双燃料发动机模拟计算

Simulation of Diesel-CNG Dual-fuel Engine

用GT-Power和AVL-Fire建立柴油-天然气双燃料发动机燃烧过程的一维模型和燃烧室三维模型,并对模型进行拟合,从一维模型中观察缸内压力、最大压力值位置、最大压力升高率和功率,从三维模型中观察燃烧因子、NOX、Soot、CO和CH4的变化情况,仿真发现:气缸最大压力值为15.92MPa,最大压力值位置723.4°CA,最大压力升高率0.75MPa/°CA;随着燃烧因子增加,缸内温度增大,在燃烧点附近产生CO、NOX、Soot开始增加;当燃烧因子减小时,缸内高温继续扩散,充满燃烧室大部分空间,CO、NOX、Soot均出现先增加后减小的变化;CH4先均匀充满整个燃烧室,在喷油开始时刻,燃烧室喷油点处的CH4浓度最大,随着燃烧的进行,CH4浓度减小,当燃烧结束后,燃烧室边沿浓度较高。

One-dimensional model of diesel-CNG dual-fuel engine combustion process and three-dimensional model of combustion chamber are established by GT-Power and AVL-Fire and the model is fitted.The maximum pressure,the position of maximum pressure,the rise rate of maximum pressure and power in cylinder are observed from the one-dimensional model.The changes of combustion factors,NOX,Soot,CO,and CH4 are observed from the three-dimensional model.The results show that the maximum pressure is 13.92MPa,the position of maximum pressure is 723.4°CA,the rise rate of maximum pressure is 0.75MPa/°CA.With the increase of combustion factor,the temperature increase in cylinder.The CO,NOX,Soot begin to increase near the combustion point.When the combustion factor decreases,the high temperature continue spreads in the cylinder and fills most of the combustion chamber space,CO,NOX and Soot increase first and then decrease.CH4 fills the whole combustion chamber evenly.At the beginning of injection,CH4 concentration is highest at injection point of the combustion chamber.With the combustion proceeding,the CH4 concentration of decreases,when the combustion is over,the concentration of CH4 is higher at the edge of the combustion chamber.