Application technique of particle image velocimetry and entropy analysis toinvestigate 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 theserequirements. Many researchers have performed studies to investigate the spraycharacteristics and the mixture formation of the GDI injector. In this work, westudied the spray characteristics of a gasoline direct injector by using entropyanalysis and particle image velocimetry (PIV) methods. The entropy analysis isbased on the concept of statistical entropy, and it identifies the degree ofhomogeneity in the fuel concentration. The PIV algorithm was developed toelucidate the correlation between entropy and vorticity. From the applied resultson a direct injection gasoline spray, we could find that the direct diffusionphenomenon was a dominant factor in the formation of a homogeneous mixturedownstream of the GDI spray, especially under vaporizing ambient conditions,and the mixing phenomenon was also progressed by momentum exchange withinduced air. In addition, these results revealed that entropy analysis and PIV arevery effective methods for the analysis of the mixing process, and the entropyvalues increase with the progress of uniformity in the diffusion process.