柴油/天然气/氢气三燃料化学动力学机理的构建

Construction of Chemical Kinetic Mechanism of Diesel/Natural Gas/Hydrogen Tri-Fuel

为探究柴油、天然气、氢气3种燃料在发动机缸内的燃烧过程,构建了含120种组分、612步基元反应的柴油/天然气/氢气(DNH)三燃料机理。对DNH机理进行点火延迟敏感性分析、反应路径分析,调整关键反应指前因子,利用Chemkin验证DNH机理的点火延迟期和层流火焰速度,同时通过计算流体动力学耦合DNH动力学反应机理的方法,对发动机缸内纯柴油、柴油/天然气、柴油/天然气/氢气3种燃烧模式进行验证。结果表明:基于高碳数多组分柴油模型构建的DNH机理,其预测结果与点火延迟期、层流火焰速度试验数据均能良好吻合;计算流体动力学耦合DNH机理的计算结果与实验测量得到的发动机缸内压力和放热率变化一致,DNH机理适用于预测柴油/天然气/氢气三燃料发动机的缸内燃烧过程。

To investigate the combustion process of diesel,natural gas,and hydrogen in the engine cylinder,a diesel/natural gas/hydrogen(DNH)tri-fuel mechanism containing 120 species and 612 steps of elementary reactions was constructed.The ignition delay sensitivity analysis and reaction path analysis were carried out on the DNH mechanism,the key reaction preexponential factors were adjusted,and the ignition delay time and laminar flame speed of the DNH mechanism were verified by Chemkin.Meanwhile,the three combustion modes of pure diesel,diesel/natural gas,and diesel/natural gas/hydrogen in the engine cylinder were verified by the method of computational fluid dynamics coupling DNH kinetic mechanism.The results show that the predicted results of the DNH mechanism constructed based on the high carbon number multi-component diesel model are in good agreement with the experimental data of ignition delay and laminar flame velocity.The calculation results of DNH mechanism coupled with computational fluid dynamics are consistent with the changes of pressure and heat release rate in the engine cylinder measured by experiments,and the DNH mechanism is suitable for predicting the in-cylinder combustion process of a tri-fuel engine.