二甲醚低温低压自点火行为的实验和理论研究

针对二甲醚(DME)低温低压数据缺乏和反应机理认识不统一问题,利用高压激波管进行点火延迟期测量实验,实验工况完整覆盖负温度系数(NTC:Negative Temperature Coefficient)区域。使用Aramco Mech 3.0机理对实验结果进行了数值仿真,发现与实验数据相比存在两个差异较大的典型区域:NTC高温拐点前温度区和NTC低温拐点后温度区。本文通过计算流体力学(CFD:Computational Fluid Dynamics)仿真分析,说明了热点的出现可以引起第一个区域内的差异。并且本文对DME低温反应进行动力学分析,认为第二个区域内的差异源自于机理本身。考虑用三次加氧反应优化DME机理,发现该路径对DME低温化学机理的改善贡献不大。但本文中的实验数据和DME的动力学分析为进一步优化DME低温燃烧反应动力学机理提供了思路和方向。

Experimental and Theoretical Study of Dimethyl Ether Auto-ignition at Low Temperature and Low Pressure

In view of the lacking data of dimethyl ether(DME)and the inconsistent understanding of the mechanism at low temperature and low pressure,high pressure shock tube was used to measure the ignition delay times of DME.The Negative Temperature Coeficient(NTC)area is completely covered in the measurement.The experimental results were numerically simulated using the Aramco Mech 3.0.It was found that there are two typical regions that differ greatly from the experimental data:the region before the NTC high temperature inflection point and the region after the NTC low temperature inflection point.In this study,Computational Fluid Dynamics(CFD)simulation analysis is used to show that occurrence of hot spots can cause differences in the first region.In addition,the kinetic analysis of DME at low temperature is carried out in this study,and it is believed that the difference in the second region originates from the mechanism itself.Considering the use of third O2 addition reactions to optimize the DME mechanism,it is found that this path does not contribute much to the improvement of the low-temperature chemical mechanism of DME.However,the experimental data in this study and the kinetic analysis of DME provide ideas and directions for further optimizing the kinetic mechanism of DME at low temperature and low pressure.