Experimental and numerical study of flash boiling in gasoline direct injection sprays

Multi-hole gasoline direct injection (GDI) sprays under flash boiling conditions are investigated experimentally and numerically. GDI injectors produce multiple spray plumes that expand and eventually collapse under flash boiling conditions. The experimental studies provide limited information regarding the collapsing sprays. The numerical investigations provide further insight to these complex flow fields. However, the spray injection model that is generally used in spray simulation is incapable of modelling flash boiling effects. Therefore, a new spray injection model is introduced that can capture the rapid expansion of the flash boiling sprays in the near nozzle region. The spray penetrations obtained from the simulations compare reasonably well with the experimental results. The effects of air entrainment on the spray collapse are also investigated. In the end a parametric study has been performed in order to identify the important control parameters of flash boiling in GDI injectors.