The effects of intake pressure on in-cylinder gas velocities in an optically accessible single-cylinder research engine
Particle image velocimetry measurements of the flow in the intake pipe and cylinder in an optically accessible single-cylinder research engine were taken to better understand the effects of intake pressure variations on the flow field. At a constant engine speed of 1500 rpm, the optical research engine at Technische Universität Darmstadt was operated at six different intake pressure loads from 0.4 to 0.95 bar under motored operation. The average velocity fields show that the tumble center position is located closer to the piston and velocity magnitudes decrease with increasing pressure load. A closer investigation of the intake flow near the valves reveals sharp temporal gradients and differences in maximum and minimum velocity with varying intake pressure load which are attributed to intake pressure fluctuations.