Gasoline direct injection spray-wall impingement: Macroscopic characterization and optical analysis

Spray-wall interaction (SWI) plays a crucial role in spray-based processes, influencing atomization, mixing, combustion efficiency, and pollutant formation. This study investigates SWI by analyzing spray morphology and key geometrical parameters, including spray penetration, spray area, spreading behavior on a quartz wall, and post-impingement spray thickness. Three optical visualization techniques were employed to study the effects of varying injection and ambient pressures, fuel and ambient temperatures, and injector tip-to-wall distance. The impact of cold-start and other evaporative engine conditions on spray morphology was analyzed. An increase in the injection pressure, an increase in wall-to-tip distance, and a decrease in ambient back-pressure delay the start of the spray-wall interaction. Higher injection pressure leads to greater spray spreading over the wall. Regarding extinction profiles, a higher injection pressure and ambient temperature result in lower liquid concentration in the spray.