Numerical Flow Visualization Studies in Internal Combustion Engine

Abstract

The KIVA-II code was used to simulate the effects of two different piston-bowl (re-entrant and bowl-in-piston) configurationsand two intake swirl levels (0.5 and 2.0) on the structure and evolution of the flow field at the top dead center position of an internal combustion engine. The results show that high-shear regions and the consequent turbulence production occurred near the bowl entrance around top dead center during the compression stroke. The regions were created before top dead center in both chambers by the interaction of swirl and squish. The mean radial and tangential velocities produced by the re-entrant bowl were found to be consistently higher than those generated by the bowl-in-piston configuration. It was found that the re-entrant bowl assembly generated 35% more turbulence than the bow-in-piston design while the squish penetration for low intake swirl (0.5) was about 20% greater than for high intake swirl (2.0). The results from this study shows that after top dead center, high shear and reverse-squish flow occurs in both combustion chambers, however, they were more intense in the re-entrant bowl assembly. In view of the foregoing, it is recommended that the re-entrant bowl assembly be considered as the preferred choice in combustion chamber design.