Manipulating Tumble and Swirl Flows in Cylinder of a Motored Four-Valve Engine by Inlet Deflection Valve

Abstract

AbstractEffects of the inlet-stream deflection on the temporal and spatial evolution processes of the in-cylinder flow structures (tumble/swirl) and turbulence intensities in the symmetry and diametral planes of a motored four-valve, four-stroke engine are diagnosed by using a particle image velocimeter. The inception, establishment, and evolution of the tumbling/swirling vortical flow structures during the intake and compression strokes in the engine cylinder with/without inlet-stream deflection are depicted and compared. Quantitative strengths of the rotating vortical flow motions are presented by dimensionless parameters (tumble and swirl ratios) which can represent the mean angular velocity of the vortices in the target plane. The turbulence intensity is calculated by using the measured time-varying velocity data. The results show that by deflecting the inlet air-stream the tumble and swirl ratios of the in-cylinder flow are appreciably increased by about 0.1 and the turbulence intensity is increased by about 5 ∼ 10%.