Frequency Analysis of Tumble and Swirl in Motored Engines

Abstract

Frequency analysis of the turbulent velocity fluctuations was performed in an engine motored at 1000 r/min and equipped with a directed port generating tumbling flow and a helical port generating swirl. The results show that the turbulent energy generated by the breakdown of the tumbling vortex in the directed port case, although confined to frequencies below 289 Hz, is overall higher compared to that of the helical port which suggests that flame propagation in the initial stages of combustion will be faster in the tumbling flow case.