Effect of a dual air inlet port of the 4-valve CI engine on the swirl flow generated at the bottom region of the cylinder using the PIV technique

Abstract

The in-cylinder flow in diesel engines significantly affects fuel-air mixing, combustion, and emissions. The present study investigates how engine properties such as the engine speed and intake port affect the swirl flow of a single cylinder diesel engine. Using the obtained velocity data, the strength of the swirl flow was calculated and represented by swirl ratio. It is observed from experiments that, the swirl flow of a diesel engine is affected by changing the engine speed and the area of the intake port, in which the center position of the swirl flow was identified during intake and compression strokes. Besides, the in-cylinder flow is also affected by the opening area of the helical port such that when the opening increases, the center of swirl flow moves away from the center of cavity and the swirl ratio becomes smaller. Furthermore, by reducing the aperture of the helical port a more stable swirl was acquired. The obtained experimental results revealed that, the tangential port which generates a large-scale intake flow interacted with the small-scale swirl flow generated by the highly tilted helical port. Additionally, the inflow created by the helical port disturbed the swirl flow generated by the tangential port. The results also illustrated that the tangential port showed a higher amount of turbulent kinetic energy inside the piston concavity. In addition, tangential port leads the turbulent kinetic energy toward the outer periphery and helical port resulted to the inner side of piston concavity.