Liquid and vapor spray characterization from a multi-hole gasoline fuel injector under engine-like conditions

The direct injection of fuel in SI engines has a beneficial effect on engine performances, allowing to increase its efficiency and to reduce the gaseous exhaust emissions especially when the engine works at lean-mixture conditions.Due to the high injection pressures, one of the major drawbacks of the GDI systems is the impingement of liquid fuel on the combustion chamber wall that produces an increasing of HC emissions and soot formation due to the fuel film deposits on the piston head. The study of the wall-spray interaction and liquid film behavior may contribute a better understanding of the mixture preparation including cold starts.In this work, the spray-wall interaction of a GDI spray impinging on a flat wall was investigated at different ambient temperatures and densities in a constant volume vessel.An aluminum flat plate was positioned 22.5 mm apart from the tip of a multi-hole GDI injector and placed orthogonally to the injector axis. The ambient temperature inside the vessel was kept constant at the same wall temperatures. The effects of the temperature were evaluated by measuring the main macroscopic characteristics of the impact like width and thickness both for liquid and vapor phases