SC1-3: Analysis of Droplet Evaporation Process of Diesel Spray during Ignition Delay Period(SC: Spray and Spray Combustion,General Session Papers) SC1-3: Analysis of Droplet Evaporation Process of Diesel Spray during Ignition Delay Period(SC: Spray and Spray Combustion,General Session Papers)
In diesel combustion, spray evaporation and mixture formation during ignition delay period play an important role in ignition, combustion and emission production. Therefore, this study focused on diesel fuel evaporation process during ignition delay period. Two types of shadowgraph photography method were employed in this experiment: single and double nano-spark shadowgraph photography methods. Single nano-spark shadowgraph photography enables us to capture relatively clear still image of evaporating spray including fuel droplets, liquid phase and vapor phase. On the other hand, double nano-spark shadowgraph photography can record the double exposure images of droplets and liquid phase that can measure droplets velocity and their flying direction. Droplets velocity and flying direction have an influence on droplets evaporation and, furthermore, mixture formation processes. Therefore, the velocity vector distribution of the droplets gives suggestive information on mixture formation during ignition delay period. Results show that spray evaporation begins immediately after start of fuel injection under the condition of high ambient temperature, in particular, at the middle of the spray. Spray atomization is fast promoted at this region, leading to ignition. The ambient temperature and injection pressure affect the droplet size and the number of droplets. Furthermore, droplets behavior, in particular flying direction at spray boundary, is strongly affected by the shear stress caused by the ambient temperature and injection pressure.
- The international symposium on diagnostics and modeling of combustion in internal combustion engines
The international symposium on diagnostics and modeling of combustion in internal combustion engines 2008.7(0), 377-382, 2008