| Direct Injection (DI) has been known for its improved performance and efficiency in gasoline spark-ignition engines. However, wall wetting is inevitable and the source of UHC and PM. In order to take advantage of the GDI technology, it is important to investigate spray wall interactions in detail. Numerical and experimental studies are carried out for spray and wall impingements in an optical constant volume vessel. The fuel film was measured spatially and temporally using the Refractive Index Matching (RIM) technique. Based on the experimental results, the effects of injection angle, injection pressure, air pressure, and air temperature on wall film were evaluated quantitatively. The CFD simulation with selected models of spray was first validated using the experimental measurements of spray visualization, and very good agreement in penetration and overall spray shape were achieved. For the wall film, the conjugate heat transfer model (CHT) was employed using Fluent, and fair agreement was obtained. |
