Multidimensional In-Cylinder Flow Calculations and Flow Visualization in a Motored Engine

Abstract

Multidimensional simulations of coupled intake port/valve and in-cylinder flow structures in a pancake-shape combustion chamber engine are reported. The engine calculations include moving piston, moving intake valve, and valve stem. In order to verify the calculated results, qualitative flow visualization experiments were carried out for the same intake geometry during the induction process using a transient water analog. During the intake process the results of the multidimensional simulation agreed very well with the qualitative flow visualization experiments. An important finding in this study is the generation of a well-defined tumbling flow structure at BDC in the engine. In addition, this tumbling flow is sustained and amplified by the compression process and in turn causes generation of a high turbulence level before TDC. Many interesting features of the in-cylinder flow structures such as tumble, swirl, and global turbulent kinetic energy are discussed.