To investigate approaches for enhancing gas exchange performance in opposed-piston two-stroke (OP2S) engines

this study investigates the effects of intake conditions and port parameters on flow characteristics and in-cylinder swirl dynamics. This study employed a hybrid methodology integrating steady-flow scavenging experiments and computational fluid dynamics (CFD) simulations

and analyzed the governing mechanisms of four critical parameters: intake pressure

scavenging pressure differential

port lift

and port inclination angle—on the discharge coefficient and swirl ratio. The results indicate that increasing the scavenging pressure difference elevates gas flow velocity. By enhancing fluid inertia

this suppresses flow separation near the ports

thereby significantly improving both the discharge coefficient and swirl ratio. Increasing the port lift intensifies flow separation along the sidewalls of the ports

thereby reducing the discharge coefficient. Simultaneously

it alters the in-cylinder velocity distribution

causing the growth rate of the swirl ratio to gradually diminish.In a clockwise-swirl-oriented port configuration

the left ports feature a large inclination angle. Variations in the left inclination angle exert negligible influence on the discharge coefficient. However

increasing the right inclination angle expands the flow separation zone along the port walls

thereby reducing the discharge coefficient. Elevating the inclination angles on both sides enhances the tangential velocity component of the gas flow

leading to a significant increase in the swirl ratio.