Comparison of Model Calculations and Experimental Measurements of the Bulk Cylinder Flow Processes in a Motored PROCO Engine

A PROCO Flow Simulation (PFSIM) model has been developed to calculate the angular velocity (swirl) and radial velocity (squish) as a function of crank angle for the four strokes of the motored engine cycle. In addition, the PFSIM model calculates the time dependent cylinder pressure, temperature and mass. The model accepts the following swirl-related parameters as input: dimensionless angular momentum and mass flow coefficients for a specific intake and exhaust system configuration. These parameters determine the intake-generated swirl which is computed from the angular momentum flux entering the cylinder during the induction process. An angular momentum flux swirl meter was used to obtain the required input data for three different intake port configurations, and calculations of the bulk cylinder flow were carried out with PFSIM for each intake port configuration. Experimental measurements of in-cylinder swirl were obtained with the spark discharge/time-of-flight method in a motored PROCO research engine for the same three intake ports. Good agreement was found between measured and calculated swirl velocities. The importance of angular momentum dissipation within the cylinder is indicated by the results of this investigation. In further model calculations, the sensitivity of swirl and squish to changes in piston geometry has been shown.