Tumble flows in gasoline direct injection engine-a study using particle image

This paper deals with the experimental investigations of the in-cylinder tumble flows in a motored single-cylinder internal combustion engine using flat and pentroof pistons at an engine speed of 1000 rev/min., during suction and compression strokes using particle image velocimetry. The two-dimensional in-cylinder tumble flow measurements and analysis are carried out in the combustion space on a vertical plane passing through the cylinder axis. To analyze the flow structure, ensemble average velocity vectors are used. Ts characterize the thumble flow, tumble ratio and average turbulent kinetic energy are made use of. At the end of compression stroke. pentroof piston showed an improvement in tumble ratio and average turbulent kinetic energy by about 41°'n and 103% compared to fla- piston. From the results, it is suggesting that the tumble flow enhancement is possible with pentroof piston.