Experimental investigation of in-cylinder wall wetting in GDI engines using a shadowgraphy method

This paper discusses an experimental approach to compare the amount of gasoline on the liner for different engine setups. This is done in a non-fired motored gasoline direct injection (GDI) test engine with transparent liner walls. The main goal is a planar observation and detection of the liner wetting using a shadowgraphy method. The area of impinged fuel on the liner is visualized. After one injection cycle the decay of the area due to evaporation can be described over the next running cycles without injection. The evaporation rate is a function of the wetted area. The amount of impinged fuel is estimated with a combination of the measured wetted area and theory of evaporation behavior.In this study three different injectors are tested under full load conditions. The injection strategies are varied. Big differences are observed between the injectors and injection strategies. Furthermore the advantages and drawbacks of the measurement method are discussed.