喷油压力对柴油喷雾两阶段着火的影响

Based on the flow-typed constant volume combustion test equipment and the CONVERGE simulation platform，the effect of injection pressure on macroscopic characteristics and two-stage ignition conversion process of a diesel free jet under cold start conditions were studied. The results show that the liquid penetration distance is slightly larger under lower injection pressure of 20 MPa. The gas phase spray penetration distance and the gas/liquid phase spray cone angle increase with the increase of injection pressure，leading to a larger mixture area in the spray head region. The local distributions of temperature and equivalence ratio in the spray are similar under different injection pressures. The areas of higher temperature and lower equivalence ratio increase with the increase of the injection pressure，which promotes the low-temperature reaction. On the other hand，the higher injection pressure increases the spray flow rate，which inhibits the accumulation of CH₂O and heat in the low-temperature region of the spray，further deteriorating the transition from the low-temperature stage to the high-temperature stage. The high-temperature ignition preparation process is also prolonged. And finally，the high-temperature ignition delay time shows a trend of first decreasing and then increasing with the increase of injection pressure.