One way of improving the performance of diesel engines is to produce modifications in the fuel supply systems. In this article, the effects of creating rotationary flow inside the nozzle and changing fuel injection angle on the performance and emission of caterpillar diesel engine have been examined in two separate stages using AVL FIRE software. First, the injector and its spray have been simulated with various geometries. The numerical results of this step indicate that creating rotationary flow inside the nozzle decreases the penetration length, while increases fuel spray cone angle and improves atomization quality. In the subsequent step, the diesel engine has been simulated with its conventional and different nozzle hole geometries and injection angles. The numerical results of this step show that the nozzle with grooves has better performance and lower emission compared to other geometries. In this case, the fuel consumption decreases by 37 percent than that of the cylindrical one, while the engine power and its torque increase by 75 percent than the cylindrical nozzle hole. In addition, the amount of nitrogen oxide (NOx) and carbon monoxide for the grooved nozzle geometry reduces by 45.45 percent and 42.73 percent, respectively, than cylindrical nozzle hole, while the soot produced during the combustion process is well oxidized.

提高柴油发动机性能的一种方法是对燃料供应系统进行改造。在本文中，使用 AVL FIRE 软件在两个不同的阶段研究了在喷嘴内产生旋转流和改变燃油喷射角度对履带式柴油发动机性能和排放的影响。首先，喷射器及其喷雾已用各种几何形状进行了模拟。该步骤的数值结果表明，在喷嘴内产生旋转流会减少穿透长度，同时增加燃料喷雾锥角并提高雾化质量。在接下来的步骤中，柴油发动机已通过其传统的和不同的喷嘴孔几何形状和喷射角度进行了模拟。这一步的数值结果表明，与其他几何形状相比，带有凹槽的喷嘴具有更好的性能和更低的排放。在这种情况下，油耗比圆柱型降低37%，而发动机功率和扭矩比圆柱型喷孔提高75%。此外，凹槽喷嘴几何形状的氮氧化物 (NOx) 和一氧化碳量比圆柱形喷嘴孔分别减少 45.45% 和 42.73%，同时燃烧过程中产生的烟尘得到很好的氧化。