Abstract
This study reports aerodynamic results from in-cylinder velocity investigation carried out on a 4 valve pent roof engine, using a PIV system. The measurements were obtained using a RENAULT transparent single cylinder engine in motored conditions. PIV technique is well adapted to study this kind of flow and allowed us to investigate swirl motion for a flat top piston and for a centered bowl piston. Tumble motion was studied for a flat top piston and for a curve shape piston.
It appeard that curved piston modifies the tumble motion structure. Roll motion is shifted under the exhaust valves and rotation charge speed is increased during the compression. Swirl motion is also sharply modified by the piston bowl. Whereas swirl is composed of a tilted roll in flat piston case, piston bowl allows a solid body rotation be obtained in the bowl at the end of compression.