二甲醚重整气对二甲醚均质压燃影响的数值模拟

Numerical Simulation on the Effect of DME-Reformed Gas on Dimethyl Ether Homogeneous Compression Ignition

应用单区模型结合详细化学反应动力学机理,计算了添加二甲醚重整气对二甲醚HCCI燃烧过程的影响,并从化学动力学角度详细分析了重整气组分对燃烧机理的影响.结果表明:添加重整气可以提高缸内压力和温度,延迟着火时刻,在一定程度上拓宽发动机的负荷范围;H2和CO都能提高缸内的压力和温度,在添加相同量时,CO能获得更高的缸内压力和温度峰值,着火时刻的延迟主要受H2的影响;H2主要是在低温反应阶段通过消耗OH自由基来控制着火,CO主要参与高温氧化反应放出大量热量.

The effects of DME-reformed gas on HCCI combustion of DME were investigated using a sin- gle-zone model combined with the detailed DME chemical reaction mechanism. The effect of reformed gas composition （H2 and CO）and the effect of reformed gas on HCCI combustion were analyzed in details. Results show that addition of DME-reformed gas increases the in-cylinder pressure and temperature, retard the ignition timing, and extend the load of HCCI combustion. Both H2 and CO will increase the in- cylinder pressure and temperature. When same amount of H2 and CO was added to the DME, CO leads to the increased in-cylinder pressure and temperature, While H2 dominates the changes in combustion phas- ing. H2 controls the ignition timing by consuming OH radical at low-temperature reaction stage, and CO causes higher heat release at high-temperature reaction stage.