喷油角度对低速二冲程船用柴油机燃烧的影响

Effect of the fuel injection angle on the combustion of a low-speed two-stroke marine diesel engine

针对低速二冲程船用柴油机燃烧过程中复杂的油气混合问题,本文采用CFD软件CONVERGE研究了喷油角度对某低速二冲程柴油机混合气形成、燃烧和排放的影响,并给出了喷油角度优化策略。结果显示:顺涡流方向调整喷油角度降NOx潜力较大,当喷油角度α=23°时,NOx排放相比原机降低了22.1%;通过综合调整涡流方向和垂直方向喷油角度,优化了发动机NO x排放和BSFC的综合表现,(α=13°,β=22°)喷射角度可实现较低的NO x排放;无EGR时得到的燃油喷射角度优化策略,在EGR氛围下同样适用。

To investigate the fuel-air mixing problem in the combustion process,the effect of injection angle on the formation,combustion,and emission characteristics of fuel air mixture of a low-speed two-stroke marine diesel engine was numerically studied using a three-dimensional CFD software CONVERGE,and the optimizing strategy of the injection angle was obtained.The results show that the potential of NO x emission reduction is larger by adjusting the injection angle along the swirl direction.The NO x emission decreased by 22.1%compared with that of original engine when the injection angle was 23°.The general performance of the engine NO x emission and BSFC can be further optimized by comprehensively adjusting the injection angles along both swirl and vertical directions,and the injection angles(α=13°,β=22°)can realize lower NO x emission reduction without deteriorating the fuel consumption rate.Furthermore,the optimizing strategies of fuel injection angle obtained without EGR are also applicable in EGR atmosphere.