低温低密度下喷油压力对柴油喷雾火焰特性影响

Igniting diesel engines under low-temperature and low-density conditions is difficult. Experiments under the injection pressures of 40, 80, 120, and 160 MPa were performed at 723 K and 14 kg/m³ in a constant volume vessel to solve the problem of difficult diesel engine ignition. Flame images were captured through a high-speed direct imaging technique. Blue flame was distinguished from hot flame, and two-color analysis was implemented. Results showed that flame take-off length increased with the increase in injection pressure, whereas flame temperature decreased. Therefore, the blow-off effect and the evaporation cooling effect intensified with the increase in injection pressure, and high injection pressure was not conducive for stable flame combustion under low-temperature and low-density conditions.