Abstract
An experimental study has been made in order to analyse the transient internal structure of the spray of a high pressure-swirl injector for Spark-Ignited Direct-Injection (SIDI) gasoline engines.
The spray development process has been visualized using an imaging system including a CCD camera, a frame grabber, a strobe flash and a digital image processing software.
The images have been taken in different times from the start of injection both along the spray axis and in cross sections located in the range 1 - 40 mm (step 5 mm) from the tip of the injector.
The acquisition of the spray cross-section images has allowed a detailed analysis of the spray internal structure and its temporal and spatial evolution.
It has been possible to visualize the formation and the spatial and temporal evolution of the initial liquid slug (pre-spray) and of the hollow-cone and solid cone spray structure. Many changes in the internal spray structure at different distances from the nozzle have been observed.
The effects of the injection pressure on the spray structure have been also shown.