Abstract
The advantages of gasoline direct-injection are intake air cooling due to fuel vaporization which reduces knocking,
additional degrees of freedom in designing a stratified injection mixture, and capability for retarded ignition timing
which shortens catalyst light-off time. Stratified mixture combustion designs often require complicated piston shapes
which disturb the fluid flow in the cylinder, leading to power reduction, especially in turbocharged gasoline
direct-injection engines. Our research replaced the conventional shell-type shallow cavity piston with a dog dish-type
curved piston that includes a small lip to facilitate stratification and minimize flow disturbance. As a result, stable
stratified combustion and increased power were both achieved.
