DME分布特征对微火源引燃汽油混合燃烧过程的影响

Effects of Dimethyl Ether Distribution Characteristics on Micro Flame Ignition Hybrid Combustion

为研究二甲醚(DME)分布特征对混合燃烧的控制问题,构建了Frossling Drop Evaporation模型耦合Boiling模型,用以模拟DME蒸发过程.定容燃烧弹实验结果表明,该模型可以较准确预测DME油束贯穿距、喷雾形态.应用三维CFD数值仿真手段,分析了不同喷油时刻对DME分布及燃烧过程的影响.结果表明,早喷工况DME呈现离散型分布特征,火核发展期DME与PRF同步消耗,呈现多点自燃顺序放热特征;晚喷工况DME呈现集聚型分布特征,燃烧初期DME消耗量达75%,高度集聚的DME发挥高能点火源的作用,放热过程呈现双峰特征.基于DME分布特征的控制可以实现对微引燃汽油混合燃烧过程的调控.

To study the control of dimethyl ether（DME） distribution characteristics over mixed combustion,Frossling Drop Evaporation model and Boiling model are coupled to simulate the DME evaporation process. The experiment of constant volume combustion bomb demonstrates that the model can accurately predict the penetration length and pattern of DME spray. 3 D CFD numerical simulation is used to analyze the influence of different timing of injection on DME distribution and combustion process. Results indicate that early-injection DME is in discrete distribution. In the stage of flame nucleus,DME and PRF are in synchronous consumption,both of which indicate the feature of multi-point sequential combustion and heat release. Late-injection DME is in congregate distribution. In the initial stage of combustion,DME consumption rate reaches 75%. Highly congregate DME produces adequate energy to ignite the fire source,and displays the trait of doublet heat release. The combustion process of micro ignition gasoline can be adjusted by the control based on DME distribution characteristics.