ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-472-4
ISBN Online: 978-1-56700-471-7
3rd Thermal and Fluids Engineering Conference (TFEC)
THERMAL INVESTIGATION OF A GDI MULTI-HOLE SPRAY IMPACT ON A HEATED THIN FOIL
要約
Investigation about operating conditions in modern Gasoline Direct Injection (GDI) engines keeps awake the
interest of car manufacturers in order to be respectful of the strict rules about pollutant emissions imposed
by states' laws and regulations. It is well-known the strong influence of surface temperature on droplet-wall
interaction and the resulting liquid film formation. On the other side, it is poor the quantitative knowledge
about the temperature drop on impact zones and about detection of liquid and gaseous phases after the impact
on piston head. The present study focuses on the application of infrared thermography about a multi-hole GDI
injector generated spray impinging on a heated thin foil. Thermal images of the iso-octane fuel impacting on
the heated thin foil are acquired at different delays starting from the impact time. Each acquisition is repeated
in order to obtain phase-averaged images. A parametric study is driven about injection pressure at fixed
wall temperature and nozzle-to-wall distance. The temperature difference maps and the temperature dynamic
behavior on a single impact spot are presented. A threshold selection method (Otsu's method) is then applied
on thermal images in order to distinguish the liquid wall film from the cooler dry regions. From temperature
difference images, the temperature drop on the impact zones is of about 35°C starting from the first instants
after the impact. As a matter, after about 0.5ms, the slipping of the fuel from the center of the impact area
appears.