Analysis on In-Cylinder Flow by Means of LDA, PIV and Numerical Simulation under Steady State Flow Condition

This paper describes the evaluation of flow characteristics inside a model engine cylinder using particle image velocimetry (PIV), laser Doppler anemometry (LDA), and numerical simulation by Partial Cells in Cartesian coordinate (PCC) method. The main goal of the study is to clarify the differences in the velocity characteristics obtained by these methods. The model engine head has a four-valve system. Single- and dual- valve opening conditions of the model engine head were tested by a steady flow test rig. The flow structures were completely different for these valve opening conditions. The mean velocities and their distributions obtained by the three methods show satisfactory agreement. However, there were differences in the turbulence intensities under several conditions and measuring positions. Taylor's hypothesis in the integral length scale of turbulence was also compared with single LDA and PIV measurements. The integral length scales of turbulence estimated by LDA mostly agreed with PIV results. The PCC method developed for a simpler, straightforward simulation program for engine design applications gave reasonable data, although slight differences in the velocity distribution were recognized in the critical flow conditions. Furthermore, a more detailed turbulence analysis for the flow structure was also conducted.