基于Kiva3v的柴油机进气和压缩过程模拟

Simulation of Diesel Engine Induction and Compression Based on Kiva3v Code

借助专业的网格划分软件,生成带有螺旋进气道的柴油机分块结构化六面体计算网格,基于ki-va3v程序,建立了柴油机的进气压缩仿真模型。计算发动机倒拖的缸内压力,外特性工况点的进气量,并与试验值进行了对比,结果显示吻合较好。分析了缸内的滚流比与涡流比以及缸内的流场变化。缸内涡流比的变化过程对发动机转速的变化不敏感,在压缩上止点达到了最大值。缸内的气流流场在进气压缩过程中变化复杂,产生的涡旋经历了生成、发展和衰减的演变过程。在压缩过程中,缸内的湍流强度在燃烧室区域最强。

Using a commercial mesh generation software, the multi block-structured hexahedron grid of a diesel engine with helical intake port was created. Based on the kiva3v code, the simulation model of diesel engine induction and compression processes was built. Cylinder pressure with no combustion and inflow mass per cycle at full load speeds were computed. Comparing the simulations with the experiments, it is showed that the results are of good agreement. The velocity field, swirl and tumble ratio in cylinder were analyzed. The swirl ratio is insensitive to the engine speeds, and reaches the maximum at top death center（ TDC ）. The ve- locity field in cylinder is very complicated, displaying the evolvement process of eddy generating, growing and attenuating. Turbulence intensity in combustion chamber is the strongest in cylinder during compression process.