Flow visualization and particle tracking velocimetry (PTV) were used to study the in-cylinder flow field produced by a 4-valve engine head during the intake process. Several intake configurations were considered, and their effects on the in-cylinder flow structures were assessed. The engine head was mounted on a special single cylinder water analog for the in-cylinder flow visualization and PTV experiments. The results for this study indicate that the in-cylinder flow field during the induction process is comprised of several large scale vortical motions on different planes within the engine cylinder. These large scale fluid motions are, in most cases, stable and highly repeatable from cycle to cycle. No significant in-cylinder tumbling motion was observed in the engine with both intake valves operating. The only well-defined tumbling flow structure was observed with shrouded intake valve configurations. In this case, the in-cylinder flow was dominated by a strong axial-plane vortex which filled the entire cylinder volume. Using the measured velocity fields, tumble and swirl ratios were evaluated under transient conditions.
THE IN-CYLINDER FLUID MOTION in internal combustion engines is one of the most important factors controlling the combustion process. It governs the flame propagation rate in homogeneous charge spark-ignition engines; it controls the fuel-air mixing and burning rates in diesels [
One of the most attractive techniques for characterization of the large scale fluid motion during the intake process in internal combustion engines is water flow visualization [
The aim of the present work is to conduct an extensive in-cylinder flow visualization study of the intake-generated fluid motion produced by a 4-valve engine head with different intake configurations. The engine head was mounted on a single-cylinder transient water analog (engine) [