Comparison of Spray Structures of Diesel and Gasoline Using Modified Evaporation Model in Openfoam CFD Package 2014-01-1417
Researches about gasoline direct injection compression ignition engine (GDCI), a compression Ignition (CI) engine fueled with gasoline instead of diesel, are getting great attention for operation of the CI engine under higher load conditions with low smoke and nitrogen oxides (NOx) emission due to high volatility and low auto-ignitability of gasoline. In this engine, it is very important to investigate gasoline spray characteristics inside the cylinder compared to diesel. Recently, many researchers are using computational fluid dynamics (CFD) as a useful tool to investigate the spray characteristics of these two fuels inside the internal combustion engines.
To simulate gasoline and diesel sprays inside the cylinder, higher volatility of gasoline than those of diesel should be considered properly. Of many spray sub-models, evaporation model is more important model to simulate liquid-vapor phase change in evaporating condition and the accuracy of calculated liquid length is decided by this model.
In this study, iso-octane and n-heptane were used as surrogate fuels for gasoline and diesel and the evaporation model, which was modified to consider fuel distillation curve, was used to simulate liquid and vapor distribution of two fuels in a CI engine. OpenFOAM was used as the CFD tool. The CFD liquid length results were validated with experimental data. CFD results showed that fuel volatility make lower ambient temperature around the main spray for gasoline and diesel.