Study on the reconstruction mechanism of combustion reaction kinetics driven by in-cylinder pressure waves

To reveal how pressure waves affect the diesel combustion reaction network, this study integrated engine experiments with 3D fluid simulations and 0D chemical kinetics. The mains results are as follows: (1) Coupling and decoupling between pressure wave and local combustion, governed by local mixture composition. During the transition from low-temperature reaction (LTR) to high-temperature reaction (HTR) (high CH₂O), the pressure wave strongly couples with the high-temperature front. (2) Pressure wave compression breaks CH₂O/H₂O₂ bottlenecks, forcing reaction acceleration and building a radical pool, which triggers fast chain branching. The combustion reaction network shifts from a slow pathway (H₂O₂/HO₂-dependent) to a highly efficient pathway (H/O/OH-dominated), establishing a positive feedback loop (CO oxidation → H generation → chain branching → OH regeneration). The local heat release then feeds back to the pressure wave, offsetting diffusion loss and raising peak pressure to 26.7 MPa. (3) In the fully reacted HTR region (low CH₂O, high OH), decoupling occurs: the local high-temperature front separates from the pressure wave front, reducing the wave's influence on the combustion reaction and causing the wave to rapidly weaken due to propagation dissipation, with a secondary heat release occurring due to product thermal dissociation and recombination (peak 3115 K). These findings clarify pressure wave driven combustion reaction network reconstruction and offer a theoretical basis for knock and extreme combustion.