Numerical simulation and experiment on spray characteristics of GDI engines

Spray characteristics of high-pressure swirl type of gasoline direct injection(GDI)injector are investigated experimentally and numerically. Visualized experiment was carried out in a constant volume chamber using high speed CMOS camera. Spray penetration, spray cone angle, spray tip velocity and droplet characteristics were measured at different injection pressures and injection durations as well as different ambient pressures. Results show that at low ambient pressure, the spray shows a hollow cone pattern with wide spray angle which is beneficial to the preparation of homogenous mixture, while the spray exhibits a solid compact cone pattern at high ambient pressure which produces the stratified mixture. The correlated empirical equation for spray penetration is validated by the experimental results. Numerical analysis was made based on one-dimensional model in the AVL HYDSIM environment. Consistency in needle lift is found between the model prediction and measured.