Flow Visualization Study of the Intake Process of an Internal Combustion Engine

The efficiency of combustion and the production of pollutants in the internal combustion engine are strongly dependent on the turbulent flow field in the engine cylinder. In most engines, turbulence is almost exclusively generated during the induction stroke. A water analog was used to visualize and study this process for a simple geometry cylinder.

The flow field, during the induction process, was observed to be structured and highly repeatable from cycle to cycle. The structure was comprised of two ring vortices, of concentrated vorticity, which were of the same scale as the engine cylinder. A detailed study of the characteristics of the vortex rings was carried out for the case of an axisymmetric cylinder geometry. Inviscid scaling laws were obtained from these results that describe the development and stability of the structured flow field.