Intake Swirl Process Generated by an Engine Head: a Flow Visualization Study

In-cylinder charge swirl is used in many internal combustion engines to promote combustion. The purpose of this work is to investigate the in-cylinder swirl characteristics generated by an engine head during the induction process by means of flow visualization and Particle Tracking Velocimetry (PTV). The study was carried out for an engine head with a shrouded intake valve in a special single-cylinder transient water analog. The results revealed that the in-cylinder swirl generated by the shroud is characterized by a strong single vortex with its center of rotation eccentric to the cylinder axis. The location of the center rotation differs from plane to plane along the cylinder axis. Furthermore, velocity data obtained for this study suggest that the in-cylinder swirl is not solid body rotation. Finally, the velocity fields were integrated and an equivalent swirl was calculated for the engine under transient conditions.