The ignition process, mode of combustion and reaction front propagation in a partially premixed combustion (PPC) engine running with a primary reference fuel (87% iso-octane, 13% n-heptane by volume) is studied numerically in a large eddy simulation. Different combustion modes, ignition front propagation, premixed flame and non-premixed flame, are observed simultaneously. Displacement speed of CO iso-surface propagation describes the transition of premixed auto-ignition to non-premixed flame. High temporal resolution optical data of CH₂O and chemiluminescence are compared with simulated results. A high speed ignition front is seen to expand through fuel-rich mixture and stabilize around stoichiometry in a non-premixed flame while lean premixed combustion occurs in the spray wake at a much slower pace. A good qualitative agreement of the distribution of chemiluminescence and CH₂O formation and destruction shows that the simulation approach sufficiently captures the driving physics of mixed-mode combustion in PPC engines. The study shows that the transition from auto-ignition to flame occurs over a period of several crank angles and the reaction front propagation can be captured using the described model.

在大型涡流模拟中，对采用主要参考燃料（87％的异辛烷，13％的正庚烷）运行的部分预混燃烧（PPC）发动机的点火过程，燃烧方式和反应前沿传播进行了数值研究。同时观察到不同的燃烧模式，点火前传播，预混火焰和非预混火焰。CO等值面传播的位移速度描述了预混合自燃向非预混合火焰的过渡。CH _2的高时间分辨率光学数据将O和化学发光与模拟结果进行比较。可以看到高速点火前沿通过富含燃料的混合物膨胀，并在非预混火焰中稳定在化学计量附近，而稀薄的预混燃烧则以较慢的速度在喷雾尾流中发生。化学发光的分布以及CH ₂ O的形成和破坏的良好定性一致表明，该模拟方法充分捕获了PPC发动机混合模式燃烧的驱动物理特性。研究表明，从自动点火到火焰的过渡发生在几个曲柄角的时间段内，并且可以使用所描述的模型捕获反应锋面的传播。