In-cylinder flame luminosity measured from a stratified lean gasoline direct injection engine

In-cylinder flame luminosity has been used to diagnose combustion process and the formation of soot emissions in compression-ignition engines. Increased soot particle emissions from spark-ignited gasoline direct injection (GDI)engines, especially those with stratified fuel-air mixtures, requires investigation of responsible anomalous flame behavior. In this work, spatiotemporal in-cylinder flame luminosity is reported from a lean stratified operating condition in a modern GDI engine. Significant fuel mass injected near top dead center led to detectable piston-top pool fires that have previously correlated to significant soot particle emissions. The demonstrated result shows that measuring in-cylinder flame luminosity is a viable tool for identifying soot-causing flames in GDI engines.