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Characteristics of the in-cylinder air motion in Diesel engine has been investigated owing to Particle Imagery Velocimetry (PIV). Measurements have been performed in a full transparent engine, respecting real diesel engine geometry configuration (in particular high compression ratio). Two different piston shapes have been studied: flat and bowl-in-piston. A first paper (2003-01-3083, Pittsburgh congress October 2003) describes experimental set up which allowed to obtain very high quality measurements until the Top Dead Centre (TDC), and presents results of Diesel internal aerodynamics flow based on mean averaged velocity fields [1]. The present paper shows the second part of this study and is focused on turbulence evolution from intake to exhaust phases.

An experimental investigation is carried out on in-cylinder motion, during the intake and compression strokes of a spark-ignited multi-valve engine. This study is conducted on a single cylinder four valve research engine. The engine is equipped with several optical accesses on cylinder liner and cylinder head. The turbulence and local velocity in combustion chamber were measured by Laser Doppler Velocimetry. Furthermore, effects of different bowl shapes on turbulence, cycle by cycle flow variations, and tumble distortion were studied. Tumble velocity field exhibits a triplet vortices structure composed of one vertical and two horizontal vortices. This structure is induced during the inlet stroke, and remains during compression. In the latest stage of compression, tumble is converted into a pair of horizontal vortices. Velocity measurements in the cylinder show a precession motion of tumble center. Distortion of tumble is very unstable and perturbed with a flat top piston.