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Impingement of spray against the cylinder wall or piston bowl is an unavoidable physical process in homogeneous charge compression ignition (HCCI) and premixed charge compression ignition (PCCI) engines using early injection strategy. It directly affects fuel-air mixture formation, combustion and exhaust emission. In addition, the alcohol fuels such as methanol, ethanol and n-butanol are regarded as hopeful alternative fuels as well as fuel additive for HCCI and PCCI diesel engines to improve the emission level. The better understanding for the effect of alcohol-diesel blending fuel on the spray-wall impingement process is helpful for the improvement of HCCI and PCCI diesel engines. In this paper, the effects of three different alcohol-diesel blending fuels (methanol, ethanol and n-butanol) on the spray-wall impingement process were studied. Numerical investigation was performed in AVL FIRE code.

Impingement of injected fuel spray against the cylinder liner (wall wetting) is one of the main obstacles that must be overcome in order for early injection Homogeneous Charge Compression Ignition (EI HCCI) combustion. In the strategies to reduce or prevent wall wetting explored in the past, limiting the spray cone angle was proved to be a useful approach. This paper is presented to study the effect of the spray cone angle on the mixture formation, particularly the region near the cylinder wall (wall wetting region), and CO/Soot emissions of an EI HCCI diesel engine. Three-dimensional modeling was performed in AVL FIRE code. The calculation grid was divided into three regions which were defined as the combustion chamber region, the wall wetting region, and the central regions. The history of the CO/soot mass of each region and the equivalent ratio/temperature (φ-T map) of wall wetting region were analyzed.