Diesel Spray and Adhering Fuel on an Impingement Wall 2002-01-1628
Average concentration of a diesel impingement spray and characteristics of fuel adhering on a flat wall were investigated experimentally. Spray tip penetration and spray volume before and after impingement were measured on high speed photographs of the spray which was injected into a high pressure chamber of cold state. Further, the adhered fuel on the wall was directly measured by a precision balance. To clarify the characteristics of the impingement spray at various wall distances, pre-impingement spray and post-impingement spray were individually analyzed. Based on the entrainment air and fuel mass which was corrected by the adhered fuel, the air-fuel ratio was derived at various wall distances. As the results, the wall impingement of the diesel spray caused lean mixture spray concentration in comparison with the free spray. As the wall distance increased, the fuel film diameter to spray width ratio decreased. The air-fuel ratio on pre- and post-impingement spray was strongly affected by fuel mass according to elapsing time, that is, injection rate history. Also, spray concentration was considerably affected by the adhering fuel.