柴油机喷雾环境条件和喷油参数对火焰浮起长度及其空气卷吸率影响的研究

Effects of Fuel Injection Ambient Conditions and Parameters of Diesel Engines on Flame Lift-off Length and Its Air Entrained Rate

为了揭示柴油机参数对火焰浮起长度及其空气卷吸率的影响规律,采用修正的KIVA-3V软件建立了定容燃烧弹的三维数值分析模型,以2 100 K等温线作为火焰浮起长度的评价标准并进行了相关计算。研究表明,降低喷雾初始环境温度和增大喷油压力均可增大火焰浮起长度和空气卷吸率,有利于降低柴油机炭烟排放。喷雾环境密度的增加虽然减小了火焰浮起长度,但在环境温度较低的情况下,环境密度的增加会导致空气卷吸率的大幅增加。减小喷孔直径,火焰浮起长度降低,空气卷吸率却增加。燃油温度的升高会造成火焰浮起长度的轻微降低,对空气卷吸率的影响较小。

In order to reveal the law of effects of diesel engine parameters on the flame lift-off length and its air entrained rate, a three-dimensional numerical analysis model of the constant volume combustion vessel was established by using revised KIVA-3V code,and pertinent calculations were carried out by using the isotherm of 2 100 K as an evaluation standard of the edge of flame lift-off length. Simulated results indicate that with both the decrease in the initial environmental temperature of spraying and the increase in the fuel injection pressure, the flame lift-off length and its air entrained rate can increase ,which is beneficial to soot reduction of diesel engines. Although the increase in environmental densities of spraying can reduce the flame lift-off length, it will result in, under the condition of a lower environmental temperature, a significant increase of the air entrained rate. Decreasing the nozzle diameter can reduce the flame lift-off length, but the air entrained rate is increased. Increasing the initial fuel temperature can lead to a slight decrease of the flame lift-off length, and has a less influence on the air entrained rate.