Combustion Characteristics of a diesel fuel spray impinging on a wall were studied, using a constant volume combustion vessel. Pressure and temperature inside the vessel. and fuel injection specification were set at the typical values of small DI diesel engines of 90-100 mm cylinder bore size.
The indicated pressure analysis and combustion observation indicate that present analysis enables the evaluation of the mixture formation affected by impingement wall, corresponding to a small actual DI diesel engine. By lowering impingement wall temperature from 840 K to 620 K, ignition point shifts upstream along the spray from a portion near the wall, and ignition delay is shortened.
Although ignition occurs earlier at shorter impingement length, its ignition time difference become less at shorter ignition delay condition, where, however, the heat release rate changes greatly and it gives a maximum at a certain impingement length. This value almost corresponds to the break tip length of fuel spray.