Effects of Port Shape on Steady Flow Characteristics in an SI Engine with Semi-Wedge Combustion Chamber (4)-Distribution Characteristics along the Radial Direction

This paper is the last of a study comparing the steady flow characteristics according to the port shape in a semi-wedge-type combustion chamber. Based on the evaluation of the impact swirl meter and particle image velocimeter, the tangential velocity distribution and torque distribution along the radial direction were compared, and the following conclusions were drawn. The tangential velocity distribution along the radial direction approached the ideal distribution as it went downstream irrespective of the centering setting and port shape, but it was significantly lower than the theoretical value for a dimensionless radius of 0.8 or more. In addition, the sum of torque for the same dimensionless radius greatly increased when the axial speed was considered, and the increase was larger as the eccentricity was small and downstream. An analysis of the cumulative torque indicated that the area within a dimensionless radius of 0.4 hardly contributed to the total amount of torque, but the contribution of a radius of 0.8 or more was 50% or more. Finally, the effect of eccentricity occurred at a dimensionless radius of 1.2 or more. As the eccentricity was smaller, the total amount of torque was affected by the axial speed. However, when the eccentricity increased, the total amount of torque was affected by both the axial speed and eccentricity.