提出了一个适用于HCCI发动机燃烧过程研究的基础燃料骨架机理模型,包含42种物质和71个反应.骨架机理分别对不同基础燃料(PRF0、PRF60、PRF80、PRF90和PRF100)在温度为667~1,350,K下进行了着火延迟期的预测计算,与试验结果的对比是较为吻合的.HCCI发动机试验的验证表明,无论是配比的基础燃料(PRF70、PRF91.8),还是单组分燃料(PRF100),该机理对缸内燃烧及排放情况的预测均是令人满意的.由此可知,该骨架机理在HCCI燃烧方面的预测性能是可靠的,可以应用于HCCI发动机的多维模拟.敏感性分析表明,针对PRF70与PRF91.8燃料HCCI工况下的燃烧情况,异辛烷与氧气的脱氢反应和正庚烷与羟基的氧化反应对缸内着火的影响较大,CH2O、CH3是非常重要的中间自由基.
A skeletal chemical kinetic mechanism including 42 species and 71 reactions for the oxidation of primary reference fuels(PRF)was proposed and applied to simulate homogeneous charge compression igni-tion(HCCI)combustion.The ignition delay predicted by the skeletal mechanism was validated with experi-ments.Validated results show good agreements for the PRF0,PRF60,PRF80,PRF90,PRF100 fuels over temperatures in the range of 667,K to 1,350,K.Validation of the present PRF mechanism was also per-formed with experiments from HCCI engines available in the literature,and good agreement was obtained for the PRF70,PRF91.8,PRF100 fuels.Results show that this PRF mechanism gives reliable performance for HCCI combustion predictions.The present PRF mechanism can be applied to multi-dimensional CFD simulations.Sensitivity analysis indicates that for PRF70 and PRF91.8 fuels under HCCI conditions,H-atom abstraction from iso-octane molecule reaction and OH addition to n-heptane molecule have large influ-ence,and CH2O,CH3 are very important intermediate species.