2. The upward ring shaped vortex of the three test fuels (G100, E100, and E85) occurred on the surface of the spray 1.1 1.2 ms after the start of energizing. In addition, the beginning timings and development processes of the vortices of the test fuels were very similar. The vortex moved the spray droplets to the inside of the hollow cone. This characteristics of the upward ring shaped vortex produced uniform mixture formation and homogeneous distribution of the injected spray.