Application technique of particle image velocimetry and entropy analysis to investigate spray structure for gasoline direct injection injector

Abstract

To improve the fuel consumption and exhaust emission for gasoline engines, the GDI (gasoline direct injection) system was spotlighted to meet these requirements. Many researchers have performed studies to investigate the spray characteristics and the mixture formation of the GDI injector. In this work, we studied the spray characteristics of a gasoline direct injector by using entropy analysis and particle image velocimetry (PIV) methods. The entropy analysis is based on the concept of statistical entropy, and it identifies the degree of homogeneity in the fuel concentration. The PIV algorithm was developed to elucidate the correlation between entropy and vorticity. From the applied results on a direct injection gasoline spray, we could find that the direct diffusion phenomenon was a dominant factor in the formation of a homogeneous mixture downstream of the GDI spray, especially under vaporizing ambient conditions, and the mixing phenomenon was also progressed by momentum exchange with induced air. In addition, these results revealed that entropy analysis and PIV are very effective methods for the analysis of the mixing process, and the entropy values increase with the progress of uniformity in the diffusion process.