Using of shrouded valve creates high swirl ratio inside the engine cylinder. Moreover, using of
swirl generation device in the inlet port can improve this swirl ratio. In this paper, both twisted tap
and guide vanes devices inserted in the inlet port are used individually for enhancing the generated
swirl by the shrouded valve. In addition, the effect of these combinations on the volumetric
efficiency and the turbulent kinetic energy (TKE) is studied. A three-dimensional simulation model
based on SST k- ω model was used for predicting the air flow characteristics through the inlet port
and the engine cylinder in both intake and compression strokes. The results showed that the using of
twisted tap and guide vanes with the shrouded valve combinations increases the swirl ratio by 5.2%
and 2%, respectively, at the start of injection. They also increase the TKE by 145% and 86.5% but
they decrease the volumetric efficiency by about 3%.