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Experimental Investigation of the In-Cylinder Tumble Motion inside GDI
 Cylinder at Different Planes under Steady-State Condition using
 Stereoscopic-PIV

This paper describes an experimental study aimed at the characterization of the steady-state tumble motion in the cylinder of an engine using stereoscopic particle image velocimetry (Stereo-PIV). More specifically, a pentroof four valves gasoline direct injection (GDI) engine head was mounted on a modified FEV steady-state flow rig for applying Stereo-PIV at different measurement vertical tumble planes at mid cylinder, mid injector and mid valve. The flow field was described by the distribution of the ensemble average flow patterns for 1000 pairs of images for every case, vorticity contours, turbulent kinetic energy and tumble ratio. The results revealed that the higher velocities acquired at the mid valve plane improved the turbulent kinetic energy and tumble ratio compared to the other planes. There was a good level of agreement between direct and indirect methods used for calculating the tumble ratio.