On the Behavior of Fuel Spray Models in a HCCI Environment

Homogeneous Charge Compression Ignition (HCCI) is a promising new engine concept. Its successful introduction, however, hinges on the ability of overcoming several complications. One of these, wall-wetting (i.e. collision and subsequent adhesion of fuel droplets with and to the cold combustion chamber walls), is the result of injecting high-boiling fuels (e.g. Diesel) early in the compression stroke, when temperatures and pressure are still too low to facilitate an expedient vaporization. In order to predict the occurrence of wall-wetting, two fuel spray models (by Siebers [1] and Hiroyasu [2]) were subjected to validation based on experimental data. At the low temperatures, associated with HCCI injection timings, it is found that the Hiroyasu model is more in line with the experimental data.