In-Cylinder Tumble Flow Field Measurements and Predictions

Abstract

This paper presents the comparison between measured and predicted results of the in-cylinder tumble flow generated by a port-valve-liner assembly on a steady-flow test bench. The purpose was to advance the understanding of the stationary turbulence process via experimental and computational techniques in the same time. A baseline single-cylinder 4-stroke motorcycle engine was chosen. Its liner was replaced by a transparent acrylic-plastic tube and the piston was removed. This was to focus the research on the tumble flow generated by the geometry of its port, the passage of the canted inlet valve, and a dome-shaped combustion chamber. The in-cylinder turbulent flow field was measured via a 3-component laser Doppler velocimeter (LDV) point by point. A simultaneous computer simulation was carried out to predict the in-cylinder flow field of the same engine under the same operating condition, using KIVA3V—the most recent version of the KIVA code. The mean speed, turbulence intensity, tumble ratio, swirl ratio, and vortex circulation from both skills were all compared. A reasonably good level of agreement has been achieved. Both modern techniques are also validated.