The method of installing a duct in the front of the injector nozzle has been proved to be effective. This paper mainly studies the effects of fuel properties on ducted fuel injection (DFI). The gas-liquid two phases of spray under different working conditions are captured by using an optical testing system in a constant volume combustion chamber. According to the experimental results, it’s found that increasing the back pressure has a promotion effect on the DFI spray, enhancing the spray penetration and spray area relative to the free spray for diesel and gasoline. Furthermore, increasing ambient temperature can promote the effect of DFI spray for gasoline by increasing the spray penetration and spray area. However, the boosting effect is weaker for diesel DFI spray. Whether it’s gasoline or diesel, increasing the injection pressure can further enhance the DFI spray to increase the potential of the spray penetration and spray area. However, it should be mentioned that DFI boosts the spray dispersion under high back pressure conditions, but worsens the spray dispersion under low back pressure conditions, especially under flash boiling conditions for gasoline. To a large extent, DFI spray can improve spray characteristics and the fuel/air mixture compared to free spray.

中文翻译：

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柴油和汽油管道喷雾的研究

在喷油嘴前部安装管道的方法已被证明是有效的。本文主要研究燃料特性对管道燃油喷射（DFI）的影响。采用光学测试系统在定容燃烧室内捕获不同工况下的气液两相喷雾。实验结果表明，相对于柴油和汽油的自由喷雾，增加背压对DFI喷雾有促进作用，提高了喷雾穿透力和喷雾面积。此外，提高环境温度可以通过增加喷雾渗透和喷雾面积来促进 DFI 喷雾对汽油的影响。但是，柴油 DFI 喷雾的助推效果较弱。无论是汽油还是柴油，增加注射压力可以进一步增强DFI喷雾，从而增加喷雾渗透和喷雾面积的潜力。然而，应该提到的是，DFI 在高背压条件下促进喷雾分散，但在低背压条件下恶化喷雾分散，特别是在汽油闪蒸条件下。与自由喷雾相比，DFI 喷雾在很大程度上可以改善喷雾特性和燃料/空气混合物。