Abstract
The numerical analysis on three dimensional fluid motion through the intake port and cylinder of a single DOHC SI engine was performed with a commercial computational fluid dynamics simulation program. Steady induction port flow for various valve lifts have been simulated for a standard straight port, tumble port and swirl port. The computational geometry was obtained by direct interface with a three-dimensional CAD software for complicated port and valve shape. Detailed procedures were presented on the generation of the geometry and the block-structured mesh. The global flow patterns and the distributions of various quantities in the cylinder, such as pressure, velocity magnitude distributions around the valve seat regions, were examined. The computational results, such as mass flow rate, discharge coefficient, swirl ratio etc., for various valve lifts were obtained. These results were compared with the results from the steady rig test for different port shape and showed good agreements with each other.