柴油机进气管瞬态流动均匀性三维数值模拟

摘要

Three dimensional numerical simulation of transient flow for the intake manifold of diesel engine was carried out by using the computational fluid dynamics method and the change of internal flow field inside intake manifold under different working conditions was discussed during the period of intake overlapping.The influences of intake pressure, rotation speed and intake air overlapping time on outlet mass flow, intake air distributed mass and intake air greatest non-uniformity of each manifold were analyzed.The results show that the lower intake air pressure will lead to the higher intake air greatest non-uniformity.The larger intake air overlapping angle corresponds to the higher intake air greatest non-uniformity.Besides, the intake air greatest non-uniformity at low speed is higher than that of high speed.By means of increasing intake air pressure and optimizing intake manifold structure, the air distribution of intake manifold can be more uniform.%运用计算流体力学方法对柴油机进气管瞬态流动过程进行了三维数值模拟,讨论了在进气重叠期内,不同工况下进气管内部流场的变化情况.分析了柴油机进气增压压力、转速以及进气重叠时间对各进气歧管出口空气质量流量、进气分配质量、进气最大不均匀度的动态影响.计算结果表明:柴油机进气增压压力越低,进气最大不均匀度越大;进气重叠角越大,进气最大不均匀度也越大;柴油机低转速工作时的进气最大不均匀度要高于高转速最大不均匀度.通过提高进气增压压力、合理优化进气管几何结构,可以减小柴油机在进气过程中出现的进气分配不均匀现象.