Abstract: The effects of different compression ratios on intake, in-cylinder turbulent kinetic energy, roll-off ratio, and in-cylinder flow are investigated for a 1.5 L naturally aspirated hybrid dedicated gasoline engine. A three-dimensional computational fluid dynamics (CFD) simulation software is used to design six different compression ratios (13.1－16.9) to study and analyze with the rest of the parameters unchanged. The following conclusions can be drawn from the data: the in-cylinder air intake decreases with increasing compression ratio, and the degree of change is very small, only within 0.5%, which is negligible. However, an increase in the compression ratio has a significant impact on the turbulent kinetic energy within the cylinder. The maximum reduction in turbulent kinetic energy within the cylinder at the upper stop of compression is nearly 24% compared to the minimum compression ratio. This is unfavorable to the flame propagation within the cylinder. The same result can be obtained through the velocity cloud diagram within the cylinder. Moreover, the variation in the compression ratio also results in a certain degree of fluctuation in the in-cylinder tumbling ratio.

Key words: hybrid gasoline engine; compression ratio; intake characteristics

摘要： 以某 1.5 L 自然吸气混动专用汽油机为研究对象，研究了不同压缩比对进气量、缸内湍 流动能、滚流比和缸内流动的影响。采用某三维计算流体动力学（CFD）仿真软件，在其余 参数不变的情况下，设计六种不同压缩比（13.1－16.9）进行研究分析。得到如下结论：缸内 进气量随压缩比增加而先上升后下降且变化程度很小，仅为 0.5%以内，可以忽略不计；但压 缩比增加对缸内湍流动能有较大的影响，在压缩上止点时，缸内湍流动能最大降低幅度，相 较最小压缩比降低了近 24%，不利于缸内火焰传播，通过缸内速度云图也可以得到相同结果。 此外，压缩比变化也会导致缸内滚流比产生一定程度的波动。

关键词: 混动专用内燃机；压缩比；进气特性