Abstract
The fuel injection conditions for DME CI engine differ significantly from those of ordinary diesel CI engines, because the physical properties are different from the diesel fuel. The injection pressure is much lower and the nozzle orifice is bigger (<60MPa and =(p0.35, respectively). In this study, the high speed observation of combustion DME spray was performed to understand the differences between DME and diesel spray combustion using high speed video camera in constant volume vessel under engine like pressure and temperature condition. As the results, we found some major differences in flame luminosity and lift-off length. The flame luminosity of DME spray is much smaller than that of diesel flame, which means no soot is formed in DME spray combustion. The flame lift-off length is shorter, because evaporation is very fast and liquid length is shorter. In other aspects, including spray shape, penetration, and flame developing process, no significant difference could not be seen.
